Bryant Furnace 355MAV User Manual

Installation, Start-up, and Operating Instructions  
Deluxe 4-Way Multipoise  
Variable-Capacity Direct-Vent  
Condensing Gas Furnace  
355MAV  
Series F  
ama  
CERTIFIED  
®
As an ENERGY STAR®  
Partner, Bryant Heating  
& Cooling Systems has  
determined that this  
product meets the  
ENERGY STAR® guidlines  
for energy efficiency.  
REGISTERED QUALITY SYSTEM  
NOTE: Read the entire instruction manual before starting the installation.  
TABLE OF CONTENTS  
SAFETY CONSIDERATIONS.....................................................................................................................................................................................3  
INTRODUCTION..........................................................................................................................................................................................................3  
CODES AND STANDARDS .......................................................................................................................................................................................3  
ELECTROSTATIC DISCHARGE (ESD) PRECAUTION PROCEDURE ................................................................................................................6  
APPLICATIONS ...........................................................................................................................................................................................................6  
General......................................................................................................................................................................................................................6  
Upflow Applications...........................................................................................................................................................................................7  
Condensate Trap Location (Factory-Shipped Orientation) ..........................................................................................................................7  
Condensate Trap Tubing (Factory-Shipped Orientation).............................................................................................................................7  
Condensate Trap Location (Alternate Upflow Orientation).........................................................................................................................7  
Condensate Trap Tubing (Alternate Upflow Orientation) ...........................................................................................................................8  
Condensate Trap Field Drain Attachment ....................................................................................................................................................9  
Pressure Switch Tubing.................................................................................................................................................................................9  
Upper Collector Box and Inducer Housing (Unused) Drain Connections..................................................................................................9  
Condensate Trap Freeze Protection ..............................................................................................................................................................9  
Downflow Applications............................................................................................................................................................................9  
Condensate Trap Location.............................................................................................................................................................................9  
Condensate Trap Tubing .............................................................................................................................................................................10  
Condensate Trap Field Drain Attachment ..................................................................................................................................................11  
Pressure Switch Tubing...............................................................................................................................................................................11  
Condensate Trap Freeze Protection ............................................................................................................................................................11  
Horizontal Left (Supply-Air Discharge) Applications..........................................................................................................................11  
Condensate Trap Location...........................................................................................................................................................................11  
Condensate Trap Tubing .............................................................................................................................................................................11  
Condensate Trap Field Drain Attachments.................................................................................................................................................12  
Pressure Switch Tubing...............................................................................................................................................................................12  
Condensate Trap Freeze Protection ............................................................................................................................................................12  
Construct a Working Platform ....................................................................................................................................................................12  
Horizontal Right (Supply-Air Discharge) Applications........................................................................................................................13  
Condensate Trap Location...........................................................................................................................................................................13  
Condensate Trap Tubing .............................................................................................................................................................................13  
Condensate Trap Field Drain Attachment ..................................................................................................................................................14  
Pressure Switch Tubing...............................................................................................................................................................................14  
Condensate Trap Freeze Protection ............................................................................................................................................................15  
Construct a Working Platform ....................................................................................................................................................................15  
Form: II 355M-40-11  
Cancels: New  
Printed in U.S.A.  
03-02  
Catalog No. 5335-518  
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AIRFLOW  
UPFLOW  
HORIZONTAL  
LEFT  
HORIZONTAL  
RIGHT  
DOWNFLOW  
AIRFLOW  
AIRFLOW  
AIRFLOW  
A93041  
Fig. 1—Multipoise Orientations  
SAFETY CONSIDERATIONS  
Installing and servicing heating equipment can be hazardous due to gas and electrical components. Only trained and qualified personnel should  
install, repair, or service heating equipment. Untrained personnel can perform basic maintenance functions such as cleaning and replacing air  
filters. All other operations must be performed by trained service personnel. When working on heating equipment, observe precautions in literature,  
on tags, and on labels attached to or shipped with unit and other safety precautions that may apply.  
Follow all safety codes. In the United States, follow all safety codes including the National Fuel Gas Code (NFGC) NFPA No. 54-1999/ANSI  
Z223.1-1999 and the Installation Standards, Warm Air Heating and Air Conditioning Systems (NFPA 90B) ANSI/NFPA 90B. In Canada, refer  
to the current edition of the CAN/CGA-B149.1- and .2-M00 National Standard of Canada, Natural Gas and Propane Installation Codes  
(NSCNGPIC). Wear safety glasses and work gloves. Have a fire extinguisher available during start-up and adjustment procedures and service calls.  
Recognize safety information. This is the safety-alert symbol  
to the potential for personal injury.  
. When you see this symbol on the unit and in instructions or manuals, be alert  
Understand these signal words: DANGER, WARNING, CAUTION, and NOTE. These words are used with the safety-alert symbol. DANGER  
identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies hazards which could result in personal  
injury or death. CAUTION is used to identify unsafe practices which would result in minor personal injury or product and property damage. NOTE  
is used to highlight suggestions which will result in enhanced installation, reliability, or operation.  
INTRODUCTION  
The 355MAV Multipoise Condensing Gas-Fired furnaces are CSA (A.G.A. and C.G.A.) certified for natural and propane gases and for installation  
in alcoves, attics, basements, closets, utility rooms, crawlspaces, and garages. The furnace is factory-shipped for use with natural gas. A  
manufacturer’s accessory gas conversion kit is required to convert furnace for use with propane gas.  
These furnaces shall not be installed directly on carpeting, tile, or any other combustible material other than wood flooring. For downflow  
installations, a factory accessory floor base must be used when installed on combustible materials and wood flooring. Special base is not required  
when this furnace is installed on the manufacturer’s coil assembly Part No. CD5 or CK5, or when Coil Box Part No. KCAKC is used. The design  
of this furnace is not CSA (A.G.A. and C.G.A.) certified for installation in mobile homes, recreational vehicles, or outdoors. These furnaces are  
suitable for installation in a structure built on site or a manufactured residence completed at final site.  
These furnaces are shipped with the drain and pressure tubes connected for UPFLOW applications. Minor modifications are required when used  
in DOWNFLOW, HORIZONTAL RIGHT, or HORIZONTAL LEFT (supply-air discharge direction) applications as shown in Fig. 1. See details  
in Applications section.  
These furnaces are shipped with the following materials to assist in proper furnace installation. These materials are shipped in the main blower  
compartment.  
This furnace must be installed with a direct-vent (combustion air and flue) system and a factory accessory termination kit. In a direct-vent system,  
all air for combustion is taken directly from the outside atmosphere and all flue products are discharged to the outside atmosphere. See furnace  
and factory accessory termination kit instructions for proper installation.  
CAUTION: Application of this furnace should be indoors with special attention given to vent sizing and material, gas  
input rate, air temperature rise, unit leveling, and unit sizing. Improper installation or misapplication of furnace can require  
excessive servicing or cause premature component failure.  
WARNING: Improper installation, adjustment, alteration, service, maintenance, or use can cause carbon monoxide  
poisoning, explosion, fire, electrical shock, or other conditions which may cause personal injury or property damage.  
Consult a qualified installer, service agency, local gas supplier, or your distributor or branch for information or assistance.  
The qualified installer or agency must use only factory-authorized and listed kits or accessories when modifying this  
product. Failure to follow this warning could result in electrical shock, fire, personal injury, or death.  
CODES AND STANDARDS  
Before installing the furnace in the United States, refer to the current edition of the NFGC and the NFPA 90B. For copies of the NFGC and NFPA  
90B, contact the National Fire Protetion Association Inc., Batterymarch Park, Quincy, MA 02269; or American Gas Association, 1515 Wilson  
Boulevard, Arlington, VA 22209.  
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INSTALLATION  
This forced air furnace is equipped for use with natural gas at altitudes 0 - 10,000 ft (0 - 3,050m).  
An accessory kit, supplied by the manufacturer, shall be used to convert to propane gas use or may be required for some natural  
gas applications.  
This furnace is for indoor installation in a building constructed on site. This furnace may be installed in a manufactured (mobile)  
home when stated on rating plate and using factory authorized kit.  
This furnace may be installed on combustible flooring in alcove or closet at minimum clearance from combustible material.  
This appliance requires a special venting system. Refer to the installation instructions for parts list and method of installation. This  
furnace is for use with schedule-40 PVC, PVC-DWV, or ABS-DWV pipe, and must not be vented in common with other gas-fired  
appliances. Construction through which vent/air intake pipes may be installed is maximum 24 inches (600 mm), minimum 3/4 inches  
(19 mm) thickness (including roofing materials).  
LEVEL (0")  
TO  
LEVEL (0")  
TO  
Furnace must be installed level, or  
pitched forward within 1/2 inch of level  
for proper drainage. Failure will result in  
equipment or property damage. See  
Installation Manual for IMPORTANT unit  
support details on horizontal  
1/2" MAX  
1/2" MAX  
FRONT  
FRONT  
UPFLOW OR  
DOWNFLOW  
HORIZONTAL  
applications.  
This furnace is approved for UPFLOW, DOWNFLOW and  
HORIZONTAL installations.  
MINIMUM INCHES CLEARANCE TO  
COMBUSTIBLE CONSTRUCTION  
1"  
ALL POSITIONS:  
Clearance arrows  
do not change with  
furnace orientation.  
Mimimum front clearance for service 30 inches  
*
(762mm).  
DOWNFLOW POSITIONS:  
For installation on combustible floors only when  
installed on special base No. KGASB0201ALL, Coil  
Assembly, Part No. CD5 or CK5, or Coil Casing, Part  
No. KCAKC.  
0"  
§
0"  
B
A
E
C
D
V
K
I
S
E
C
A
N
R
U
F
T
HORIZONTAL POSITIONS:  
N
O
R
F
Clearance shown is for air inlet and air outlet end.  
§
S
Line contact is permissible only between lines  
formed by intersections of top and two sides of furnace  
jacket, and building joists, studs, or framing.  
120 size Furnace require 1 inch bottom clearance to  
combustible materials.  
E
R
I
C
E
E
F
D
I
*
R
S
O
30  
N
T 3"  
MIN  
0"  
Ø
§
325400-201 REV. A  
(LIT. TOP)  
0"Ø  
Vent clearance to  
combustibles 0".  
Clearance in inches.  
A99103  
Fig. 3—Clearances to Combustibles  
INSTALLER PACKET INCLUDES:  
Installation, Startup, and Operating Instructions  
Service and Maintenance Instructions  
User’s Information Manual  
Warranty Certificate  
Loose Parts Bag includes:  
Quantity  
Pressure tube extension  
Collector Box or condensate trap extension tube  
Inducer housing drain tube  
1/2-in CPVC street elbow  
Drain tube coupling  
Drain tube coupling grommet  
Vent and combustion-air pipe support  
Combustion-air pipe perforated disk assembly  
Condensate trap hole filler plug  
Vent and combustion-air intake hole filler plug  
1
1
1
2
1
1
2
1
3
2
Before installing the furnace in Canada, refer to the current edition of the NSCNGPIC. Contact Standard Sales CSA International, 178 Rexdale  
Boulevard, Etobicoke, (Toronto) Ontario, Canada M9W 1R3.  
Installation must comply with regulations of serving gas supplier and local building, heating, plumbing or other codes in effect in the area in which  
installation is made. In absence of local codes, installation must comply with the NFGC in the United States and the NSCNGPIC in Canada.  
These instructions cover minimum requirements for a safe installation and conform to existing national standards and safety codes. In some  
instances, these instructions exceed certain local codes and ordinances, especially those that may not have kept pace with changing residential  
construction practices. We require these instructions as a minimum for a safe installation.  
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A93026  
Fig. 4—Condensate Trap  
ELECTROSTATIC DISCHARGE (ESD) PRECAUTION PROCEDURE  
CAUTION: Electrostatic discharge can affect electronic components. Follow the Electronic Discharge Precautions  
Procedure listed below during furnace and servicing to protect the furnace electronic control. Precautions will prevent  
electrostatic discharges from personnel and hand tools which are held during the procedure. These precautions will help to  
avoid exposing the control to electrostatic discharge by putting the furnace, the control, and the person at the same  
electrostatic potential.  
1. Disconnect all power to the furnace. Multiple disconnects may be required. DO NOT TOUCH THE CONTROL OR ANY WIRE  
CONNECTED TO THE CONTROL PRIOR TO DISCHARGING YOUR BODY’S ELECTROSTATIC CHARGE TO GROUND.  
2. Firmly touch the clean, unpainted, metal surface of the furnace chassis which is close to the control. Tools held in hand during grounding  
will be discharged.  
3. After touching the chassis you may proceed to service the control or connecting wires as long as you do nothing that recharges your body  
with static electricity (for example; DO NOT move or shuffle your feet, DO NOT touch ungrounded objects, etc.).  
4. If you touch ungrounded objects, firmly touch a clean, unpainted metal surface again before touching control or wires.  
5. Use this procedure for installed and uninstalled (ungrounded) furnaces.  
6. Before removing a new control from its container, discharge your body’s charge to ground. If the control is to be installed in a furnace,  
follow items 1 through 4 before bringing the control or yourself in contact with the furnace. Put all used and new controls into containers  
before touching ungrounded objects.  
7. An ESD service kit (available from commercial sources) may also be used to prevent ESD damage.  
APPLICATIONS  
PROCEDURE 1—GENERAL  
Some assembly and modifications are required for furnaces installed in any of the 4 applications shown in Fig. 1. All drain and pressure tubes are  
connected as shown in Fig. 5. See appropriate application instructions for these procedures.  
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PLUG  
CAP  
COLLECTOR BOX  
DRAIN TUBE (BLUE  
& WHITE STRIPED)  
COLLECTOR BOX  
TUBE (PINK)  
INDUCER HOUSING  
(MOLDED) DRAIN  
TUBE (BEHIND  
COLLECTOR BOX  
DRAIN TUBE)  
COLLECTOR BOX  
DRAIN TUBE (BLUE)  
CONDENSATE  
TRAP  
COLLECTOR BOX  
TUBE (GREEN)  
FIELD-INSTALLED  
FACTORY-SUPPLIED  
DRAIN TUBE  
COUPLING (LEFT  
DRAIN OPTION)  
FIELD-INSTALLED  
FACTORY-SUPPLIED  
DRAIN TUBE  
FIELD-INSTALLED  
FIELD-INSTALLED  
FACTORY-SUPPLIED  
DRAIN TUBE  
COUPLING (RIGHT  
DRAIN OPTION)  
FACTORY-SUPPLIED  
1Ú2 -IN. CPVC STREET  
ELBOWS (2) FOR  
LEFT DRAIN OPTION  
A94213  
Fig. 5—Factory-Shipped Upflow Tube Configuration  
(Shown with Blower Access Panel Removed)  
PROCEDURE 2—UPFLOW APPLICATIONS  
In an upflow application, the blower is located below the burner section, and conditioned air is discharged upwards.  
A. Condensate Trap Location (Factory-Shipped Orientation)  
The condensate trap is factory installed in the blower shelf and factory connected for UPFLOW applications. A factory-supplied tube is used to  
extend the condensate trap drain connection to the desired furnace side for field drain attachment. See Condensate Trap Tubing (Factory-Shipped  
Orientation) section for drain tube extension details.  
B. Condensate Trap Tubing (Factory-Shipped Orientation)  
NOTE: See Fig. 5 or tube routing label on main furnace door to confirm location of these tubes.  
1. Collector Box Drain, Inducer Housing Drain, Relief Port, and Pressure Switch Tubes.  
These tubes should be factory attached to condensate trap and pressure switch ready for use in upflow applications. These tubes can be  
identified by their connection location and also by a color label on each tube. These tubes are identified as follows: collector box drain tube  
(blue label), inducer housing drain tube (violet label or molded), relief port tube (green label), and pressure switch tube (pink label).  
2. Condensate Trap Drain Tube.  
The condensate trap drain connection must be extended for field attachment by doing the following:  
a. Determine location of field drain connection. (See Fig. 2 or 5.)  
NOTE: If internal filter or side Filter/Media Cabinet is used, drain tube should be located to opposite side of casing of return duct attachment  
to assist in filter removal.  
b. Remove and discard casing drain hole plug button from desired side.  
c. Install drain tube coupling grommet (factory-supplied in loose parts bag) in selected casing hole.  
d. Slide drain tube coupling (factory-supplied in loose parts bag) through grommet ensuring long end of coupling faces blower.  
e. Cement 2 factory-supplied 1/2-in. street CPVC elbows to the rigid drain tube connection on the condensate trap. (See Fig. 5.) These  
elbows must be cemented together and cemented to condensate trap drain connection.  
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PLUG  
CAP  
COLLECTOR BOX  
DRAIN TUBE (BLUE  
& WHITE STRIPED)  
COLLECTOR BOX  
TUBE (PINK)  
COLLECTOR BOX  
TUBE (GREEN)  
COLLECTOR BOX  
DRAIN TUBE (GREEN)  
CONDENSATE  
TRAP  
INDUCER  
HOUSING  
DRAIN TUBE  
(VIOLET)  
A94214  
Fig. 6—Alternate Upflow Configuration and Trap Location  
NOTE: Failure to use CPVC elbows may allow drain to kink and prevent draining.  
f. Connect larger diameter drain tube and clamp (factory-supplied in loose parts bag) to condensate trap and clamp securely.  
g. Route tube to coupling and cut to appropriate length.  
h. Attach tube to coupling and clamp securely.  
C. Condensate Trap Location (Alternate Upflow Orientation)  
An alternate location for the condensate trap is the left-hand side of casing. (See Fig. 2 and 6.)  
NOTE: If the alternate left-hand side of casing location is used, the factory-connected drain and relief port tubes must be disconnected and  
modified for attachment. See Condensate Trap Tubing (Alternate Upflow Orientation) section for tubing attachment.  
To relocate condensate trap to the left-hand side, perform the following:  
1. Remove 3 tubes connected to condensate trap.  
2. Remove trap from blower shelf by gently pushing tabs inward and rotating trap.  
3. Install casing hole filler cap (factory-supplied in loose parts bag) into blower shelf hole where trap was removed.  
4. Install condensate trap into left-hand side casing hole by inserting tube connection stubs through casing hole and rotating until tabs snap  
into locking position.  
5. Fill unused condensate trap casing holes with plastic filler caps (factory-supplied in loose parts bag).  
D. Condensate Trap Tubing (Alternate Upflow Orientation)  
NOTE: See Fig. 6 or tube routing label on main furnace door to confirm location of these tubes.  
1. Collector Box Drain Tube  
Connect collector box drain tube (blue label) to condensate trap.  
NOTE: On 17-1/2 in. wide furnaces ONLY, cut tube between corrugated sections to prevent kinks from occurring.  
2. Inducer Housing Drain Tube  
a. Remove and discard LOWER (molded) inducer housing drain tube which was previously connected to condensate trap.  
b. Use inducer housing drain extension tube (violet label and factory-supplied in loose parts bag) to connect LOWER inducer housing drain  
connection to the condensate trap.  
c. Determine appropriate length, cut, and connect tube.  
d. Clamp tube to prevent any condensate leakage.  
3. Relief Port Tube  
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a. Connect relief port tube (green label) to condensate trap.  
b. Extend this tube (if required) by splicing to small diameter tube (factory-supplied in loose parts bag).  
c. Determine appropriate length, cut, and connect tube.  
E. Condensate Trap Field Drain Attachment  
Refer to Condensate Drain section for recommendations and procedures.  
F. Pressure Switch Tubing  
The LOWER collector box pressure tube (pink label) is factory connected to the High Pressure Switch and should not require any modification.  
NOTE: See Fig. 5 or 6 or tube routing label on main furnace door to check for proper connections.  
G. Upper Collector Box and Inducer Housing (Unused) Drain Connections  
1. Upper Collector Box Drain Connection  
Attached to the UPPER collector box drain connection is a factory-installed corrugated, plugged tube (blue and white striped label). This  
tube is plugged to prevent condensate leakage in this application. Ensure this tube is plugged.  
NOTE: See Fig. 5 or 6 or tube routing label on main furnace door to check for proper connections.  
2. Upper Inducer Housing Drain Connection  
Attached to the UPPER (unused) inducer housing drain connection is a cap and clamp. This cap is used to prevent condensate leakage in  
this application. Ensure this connection is capped.  
NOTE: See Fig. 5 or 6 or tube routing label on main furnace door to check for proper connections.  
H. Condensate Trap Freeze Protection  
Refer to Condensate Drain Protection section for recommendations and procedures.  
PROCEDURE 3—DOWNFLOW APPLICATIONS  
A downflow furnace application is where furnace blower is located above combustion and controls section of furnace, and conditioned air is  
discharged downwards.  
COLLECTOR BOX  
DRAIN TUBE (BLUE)  
CAP  
PLUG  
COLLECTOR BOX  
TUBE (GREEN)  
COLLECTOR BOX  
TUBE (PINK)  
COLLECTOR BOX  
DRAIN TUBE (BLUE  
& WHITE STRIPED)  
COLLECTOR BOX  
EXTENSION TUBE  
CONDENSATE  
TRAP  
INDUCER HOUSING  
DRAIN TUBE (VIOLET)  
A94215  
Fig. 7—Downflow Tube Configuration  
(Left-Hand Trap Installation)  
A. Condensate Trap Location  
The condensate trap must be removed from the factory-installed blower shelf location and relocated in selected application location as shown in  
Fig. 2, 7, or 8.  
To relocate condensate trap from the blower shelf to desired location, perform the following:  
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COLLECTOR BOX  
TUBE (GREEN)  
PLUG  
CAP  
COLLECTOR BOX  
DRAIN TUBE (BLUE)  
COLLECTOR BOX  
TUBE (PINK)  
COLLECTOR BOX  
DRAIN TUBE (BLUE  
& WHITE STRIPED)  
COLLECTOR BOX  
EXTENSION TUBE  
INDUCER HOUSING  
DRAIN TUBE  
(VIOLET)  
CONDENSATE  
TRAP  
COLLECTOR BOX  
EXTENSION  
DRAIN TUBE  
DRAIN TUBE  
COUPLING  
A94216  
Fig. 8—Downflow Tube Configuration  
(Right-Hand Trap Installation)  
1. Remove 3 tubes connected to condensate trap.  
2. Remove trap from blower shelf by gently pushing tabs inward and rotating trap.  
3. Install casing hole filler cap (factory-supplied in loose parts bag) into blower shelf hole where trap was removed.  
4. Install casing hole filler cap into blower shelf hole where trap was removed.  
5. Fill unused condenstate trap casing holes with placstic filler caps (factory-supplied in loose parts bag).  
B. Condensate Trap Tubing  
NOTE: See Fig. 7 or 8 or tube routing label on main furnace door to check for proper connections.  
Relocate tubes as described below.  
1. Collector Box Drain Tube  
a. Remove factory-installed plug from LOWER collector box drain tube (blue and white striped label).  
b. Install removed clamp and plug into UPPER collector box drain tube (blue label) which was connected to condensate trap.  
c. Connect LOWER collector box drain connection to condensate trap.  
(1.) Condensate Trap Located on Left Side of Casing  
Connect LOWER collector box drain tube (blue and white striped label) to condensate trap. Tube does not need to be cut.  
Clamp tube to prevent any condensate leakage.  
(2.) Condensate Trap Located on Right Side of Casing  
Install drain tube coupling (factory-supplied in loose parts bag) into collector box drain tube (blue and white striped label) which  
was previously plugged.  
Connect larger diameter drain tube (factory-supplied in loose parts bag) to drain tube coupling, extending collector box drain tube  
for connection to condensate trap.  
Route extended collector box drain tube directly from collector box drain to condensate trap as shown in Fig. 8.  
Determine appropriate length and cut.  
Connect to condensate trap.  
Clamp tube to prevent any condensate leakage.  
2. Inducer Housing Drain Tube  
a. Remove factory-installed cap and clamp from LOWER inducer housing drain connection.  
b. Remove and discard UPPER (molded) inducer housing drain tube which was previously connected to condensate trap.  
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c. Install cap and clamp on UPPER inducer housing drain connection where molded drain tube was removed.  
d. Use inducer housing drain tube (violet label and factory-supplied in loose parts bag) to connect LOWER inducer housing drain  
connection to the condensate trap.  
e. Connect inducer housing drain connection to condensate trap.  
(1.) Condensate Trap Located on Left Side of Casing  
Determine appropriate length and cut.  
Connect tube to condensate trap.  
Clamp tube to prevent any condensate leakage.  
(2.) Condensate Trap Located on Right Side of Casing  
Route inducer housing drain tube (violet label) directly from inducer housing to condensate trap.  
Determine appropriate length and cut.  
Connect tube to condensate trap.  
Clamp tube to prevent any condensate leakage.  
3. Relief Port Tube  
Refer to Pressure Switch Tubing section for connection procedure.  
C. Condensate Trap Field Drain Attachment  
Refer to Condensate Drain section for recommendations and procedures.  
D. Pressure Switch Tubing  
One collector box pressure tube (pink label) is factory connected to the pressure switch for use when furnace is installed in UPFLOW or  
HORIZONTAL LEFT applications. This tube MUST be disconnected and used for the condensate trap relief port tube. The other collector box  
pressure tube (green label) which was factory connected to the condensate trap relief port connection MUST be connected to the pressure switch  
in DOWNFLOW or HORIZONTAL RIGHT applications.  
NOTE: See Fig. 7 or 8 or tube routing label on main furnace door to check for proper connections.  
Relocate tubes as described below.  
1. Disconnect collector box pressure tube (pink label) attached to pressure switch.  
2. Extend collector box pressure tube (green label) which was previously connected to condensate trap relief port connection by splicing to  
small diameter tube (factory-supplied in loose parts bag).  
3. Connect collector box pressure tube (green label) to pressure switch connection labeled COLLECTOR BOX.  
4. Extend collector box pressure tube (pink label) which was previously connected to pressure switch by splicing to remaining small diameter  
tube (factory-supplied in loose parts bag).  
5. Route this extended tube (pink label) to condensate trap relief port connection.  
6. Determine appropriate length, cut, and connect tube.  
7. Clamp tube to relief port connection.  
E. Condensate Trap Freeze Protection  
Refer to Condensate Drain Protection section for recommendations and procedures.  
PROCEDURE 4—HORIZONTAL LEFT (SUPPLY-AIR DISCHARGE) APPLICATIONS  
A horizontal left furnace application is where furnace blower is located to the right of combustion and controls section of furnace, and conditioned  
air is discharged to the left.  
CAUTION: Local codes may require a drain pan under entire furnace and condensate trap when a condensing furnace  
is used in an attic application or over a finished ceiling.  
NOTE: In Canada, installations shall be in accordance with current NSCNGPIC and/or local codes.  
A. Condensate Trap Location  
The condensate trap must be removed from the factory-installed blower shelf location and relocated in selected application location as shown in  
Fig. 2 or 9.  
To relocate condensate trap from the blower shelf to desired location, perform the following:  
1. Remove 3 tubes connected to condensate trap.  
2. Remove trap from blower shelf by gently pushing tabs inward and rotating trap.  
3. Install casing hole filler cap (factory-supplied in loose parts bag) into blower shelf hole where trap was removed.  
4. Install casing hole filler cap into blower shelf hole where trap was removed.  
5. Fill unused condensate trap casing holes with plastic filler caps (factory-supplied in loose parts bag).  
B. Condensate Trap Tubing  
NOTE: See Fig. 9 or tube routing label on main furnace door to check for proper connections.  
1. Collector Box Drain Tube  
—11—  
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PLUG  
CAP  
COLLECTOR BOX  
AUXILIARY "J" BOX  
DRAIN TUBE  
(BLUE AND WHITE STRIPED)  
CONDENSATE  
TRAP  
COLLECTOR BOX  
TUBE (GREEN)  
INDUCER HOUSING  
COLLECTOR  
BOX EXTENSION  
DRAIN TUBE  
DRAIN TUBE (VIOLET)  
COLLECTOR BOX  
DRAIN TUBE (BLUE)  
COLLECTOR BOX  
EXTENSION TUBE  
DRAIN TUBE COUPLING  
COLLECTOR BOX TUBE (PINK)  
RELOCATE TUBE BETWEEN BLOWER SHELF AND INDUCER HOUSING FOR  
040, 060, AND 080 HEATING INPUT FURNACES  
A00215  
Fig. 9—Horizontal Left Tube Configuration  
a. Install drain tube coupling (factory-supplied in loose parts bag) into collector box drain tube (blue label) which was previously connected  
to condensate trap.  
b. Connect large diameter drain tube and clamp (factory-supplied in loose parts bag) to drain tube coupling, extending collector box drain  
tube.  
c. Route extended tube (blue label) to condensate trap and cut to appropriate length.  
d. Clamp tube to prevent any condensate leakage.  
2. Inducer Housing Drain Tube  
a. Remove and discard LOWER (molded) inducer housing drain tube which was previously connected to condensate trap.  
b. Use inducer housing drain extension tube (violet label and factory-supplied in loose parts bag) to connect LOWER inducer housing drain  
connection to the condensate trap.  
c. Determine appropriate length, cut, and connect tube.  
d. Clamp tube to prevent any condensate leakage.  
3. Relief Port Tube  
a. Extend collector box tube (green label) which was previously connected to the condensate trap by splicing to small diameter tube  
(factory-supplied in loose parts bag).  
b. Route extended collector box pressure tube to relief port connection on the condensate trap.  
c. Determine appropriate length, cut, and connect tube.  
d. Clamp tube to prevent any condensate leakage.  
C. Condensate Trap Field Drain Attachments  
Refer to Condensate Drain section for recommendations and procedures.  
D. Pressure Switch Tubing  
The LOWER collector box pressure tube (pink label) is factory connected to the pressure switch and should not require any modification.  
NOTE: See Fig. 9 or tube routing label on main furnace door to check for proper connections.  
E. Condensate Trap Freeze Protection  
Refer to Condensate Drain Protection section for recommendations and procedures.  
F. Construct a Working Platform  
Construct working platform where all required furnace clearances are met. (See Fig. 3 and 10.)  
—12—  
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COMBUSTION - AIR  
INTAKE  
VENT  
A 12-IN. (305 mm) MIN HORIZONTAL PIPE  
SECTION IS RECOMMENDED WITH  
SHORT (5 TO 8 FT / 1.5 TO 2.4 M) VENT  
SYSTEMS TO REDUCE EXCESSIVE  
CONDENSATE DROPLETS FROM  
EXITING THE VENT PIPE.  
30(762 mm)MIN  
WORK AREA  
3
5 / (146 mm)  
4
MANUAL  
SHUTOFF  
GAS VALVE  
ACCESS OPENING  
FOR TRAP  
DRAIN  
SEDIMENT  
TRAP  
CONDENSATE  
TRAP  
NOTE: LOCAL CODES MAY REQUIRE A DRAIN PAN UNDER THE  
FURNACE AND CONDENSATE TRAP WHEN A CONDENSING  
FURNACE IS INSTALLED ABOVE FINISHED CEILINGS.  
A93031  
Fig. 10—Attic Location and Working Platform  
CAUTION: The condensate trap MUST be installed below furnace. See Fig. 4 for dimensions. The drain connection to  
condensate trap must also be properly sloped to an open drain.  
NOTE: Combustion-air and vent pipes are restricted to a minimum length of 5 ft. (See Table 6.)  
NOTE: A 12-in. minimum offset pipe section is recommended with short (5 to 8 ft) vent systems. This recommendation is to reduce excessive  
condensate droplets from exiting the vent pipe. (See Fig. 10 or 32.)  
PROCEDURE 5—HORIZONTAL RIGHT (SUPPLY-AIR DISCHARGE) APPLICATIONS  
A horizontal right furnace application is where furnace blower is located to the left of combustion and controls section of furnace, and conditioned  
air is discharged to the right.  
CAUTION: Local codes may require a drain pan under entire furnace and condensate trap when a condensing furnace  
is used in attic application or over a finished ceiling.  
NOTE: In Canada, installations shall be in accordance with current NSCNGPIC Installation Codes and/or local codes.  
NOTE: The auxiliary junction box (J-Box) MUST be relocated to opposite side of furnace casing. (See Fig. 11.) See Electrical Connection section  
for J-Box relocation.  
A. Condensate Trap Location  
The condensate trap must be removed from the factory-installed blower shelf location and relocated in selected application location as shown in  
Fig. 2 or 11.  
To relocate condensate trap from the blower shelf to desired location, perform the following:  
1. Remove 3 tubes connected to condensate trap.  
2. Remove trap from blower shelf by gently pushing tabs inward and rotating trap  
3. Install casing hole filler cap (factory-supplied in loose parts bag) into blower shelf hole where trap was removed.  
4. Install casing hole filler cap into blower shelf hole where trap was removed.  
5. Fill unused condensate trap casing holes with plastic filler caps (factory-supplied in loose parts bag).  
B. Condensate Trap Tubing  
NOTE: See Fig. 11 or tube routing label on main furnace door to check for proper connections.  
1. Collector Box Drain Tube:  
a. Remove factory-installed plug from LOWER collector box drain tube (blue and white striped label).  
—13—  
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COLLECTOR BOX DRAIN TUBE (BLUE)  
COLLECTOR BOX TUBE (GREEN)  
CAP  
COLLECTOR BOX EXTENSION TUBE  
COLLECTOR BOX TUBE (PINK)  
PLUG  
AUXILARY “J” BOX RELOCATED HERE  
CONDENSATE  
TRAP  
COLLECTOR BOX DRAIN TUBE  
(BLUE AND WHITE STRIPED)  
INDUCER HOUSING  
DRAIN TUBE (VIOLET)  
COLLECTOR BOX  
EXTENSION TUBE  
A00214  
Fig. 11—Horizontal Right Tube Configuration  
b. Install removed clamp and plug into UPPER collector box drain tube (blue label) which was previously connected to condensate trap.  
c. Connect LOWER collector box drain tube (blue and white striped label) to condensate trap. Tube does not need to be cut.  
d. Clamp tube to prevent any condensate leakage.  
2. Inducer Housing Drain Tube:  
a. Remove factory-installed plug from LOWER collector box drain tube (blue and white striped label).  
b. Remove and discard UPPER (molded) inducer housing drain tube which was previously connected to condensate trap.  
c. Install cap and clamp on UPPER inducer housing drain connection where molded drain tube was removed.  
d. Use inducer housing drain extension tube (violet label and factory-supplied in loose parts bag) to connect LOWER inducer housing drain  
connection to condensate trap.  
e. Determine appropriate length, cut, and connect tube to condensate trap.  
f. Clamp tube to prevent any condensate leakage.  
3. Relief Port Tube  
Refer to Pressure Switch Tubing section for connection procedure.  
C. Condensate Trap Field Drain Attachment  
Refer to Condensate Drain section for recommendations and procedures.  
D. Pressure Switch Tubing  
One collector box pressure tube (pink label) is factory connected to the pressure switch for use when furnace is installed in UPFLOW or  
HORIZONTAL LEFT applications. This tube MUST be disconnected and used for the condensate trap relief port tube. The other collector box  
pressure tube (green label) which was factory connected to the condensate trap relief port connection MUST be connected to the pressure switch  
in DOWNFLOW or HORIZONTAL RIGHT applications.  
NOTE: See Fig. 11 or tube routing label on main furnace door to check for proper connections.  
Relocate tubes as described below.  
1. Disconnect collector box pressure tube (pink label) attached to pressure switch.  
2. Extend collector box pressure tube (green label) which was previously connected to condensate trap relief port connection by splicing to  
small diameter tube (factory-supplied in loose parts bag).  
3. Connect collector box pressure tube (green label) to High Pressure Switch connection labeled COLLECTOR BOX.  
4. Use remaining smaller diameter tube (factory-supplied in loose parts bag) to extend collector box pressure tube (pink label) which was  
previously connected to pressure switch.  
5. Route this extended tube (pink label) to condensate trap relief port connection.  
—14—  
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6. Determine appropriate length, cut, and connect tube.  
7. Clamp tube to relief port connection.  
E. Condensate Trap Freeze Protection  
Refer to Condensate Drain Protection section for recommendations and procedures  
F. Construct a Working Platform  
Construct working platform where all required furnace clearances are met. (See Fig. 3 and 10.)  
CAUTION: The condensate trap MUST be installed below furnace. See Fig. 4 for dimensions. The drain connection to  
condensate trap must also be properly sloped to an open drain.  
NOTE: Combustion-air and vent pipes are restricted to a minimum length of 5 ft. (See Table 6.)  
NOTE: A 12-in. minimum offset pipe section is recommended with short (5 to 8 ft) vent systems. This recommendation is to reduce excessive  
condensate droplets from exiting the vent pipe. (See Fig. 10 or 29.)  
LOCATION  
PROCEDURE 1—GENERAL  
When a furnace is installed so that supply ducts carry air to areas outside the space containing the furnace, return air must also be handled by ducts  
sealed to furnace casing. The ducts terminate outside the space containing the furnace to ensure there will not be a negative pressure condition  
within equipment room or space. Furnace may be located in a confined space without special provisions for dilution or ventilation air. This furnace  
must be installed so electrical components are protected from water.  
LEVEL (0)  
FRONT  
FRONT  
TO  
LEVEL (0)  
TO  
12MAX  
12MAX  
UPFLOW OR DOWNFLOW  
HORIZONTAL  
A93025  
Fig. 12—Furnace Location for Proper Condensate  
Drainage  
NOTE: For proper furnace operation, install furnace so that it is level or pitched forward within 1/2-in. to ensure proper condensate drainage from  
secondary heat exchangers. (See Fig. 12.)  
NOTE: These furnaces are designed for a minimum continuous return-air temperature of 60°F or intermittent operation down to 55°F such as  
when used with a night setback thermostat. Return-air temperature must not exceed a maximum of 85°F. Failure to follow these return-air  
temperature limits may affect reliability of heat exchangers, motors, and controls. (See Fig. 13.)  
A93042  
Fig. 13—Return-Air Temperature  
Locate furnace as close to center of air distribution system as possible.  
Locate furnace so combustion-air pipe lengths are not exceeded. Refer to Table 6.  
—15—  
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CAUTION: If these furnaces are used during construction when adhesives, sealers, and/or new carpets are being  
installed, make sure all combustion and circulating air requirements are followed. If operation of furnace is required during  
construction, use clean outside air for combustion and ventilation. Compounds of chlorine and fluorine, when burned with  
combustion air, form acids which will cause corrosion of heat exchangers. Some of these compounds are found in paneling,  
dry wall adhesives, paints, thinners, masonry cleaning materials, and many other solvents commonly used in the  
construction process.  
Excessive exposure to contaminated combustion air will result in safety and performance related problems.  
Provide ample space for servicing and cleaning. Always comply with minimum fire protection clearances shown on unit’s clearance to  
combustibles label. (See Fig. 3.) Locate furnace where available electric power and gas supplies meet specifications on furnace rating plate.  
FRONT  
B
A
C
K
BACK  
FRONT  
A93043  
Fig. 14—Prohibit Installation on Back  
o
32 F MINIMUM INSTALLED  
AMBIENT OR FREEZE  
PROTECTION REQUIRED  
A93058  
Fig. 15—Freeze Protection  
WARNING: Do not install furnace on its back. (See Fig. 14.) Safety control operation will be adversely affected. Never  
connect return-air ducts to back of furnace. Failure to follow this warning could result in fire, personal injury, or death.  
CAUTION: If this furnace is installed in an unconditioned space where the ambient temperatures may be 32°F or lower,  
freeze protection measures must be taken. (See Fig. 15.)  
PROCEDURE 2—LOW-FIRE ONLY INSTALLATION  
This 355MAV furnace can be installed to operate in the low-fire only heating mode when sized using the low-fire heating capacity. This is  
accomplished by placing setup switch SW-2 in the ON position to provide only low-fire-heat operation. See Fig. 31 and Table 11. With this setup,  
high-fire operation will not occur.  
When the model no. on the furnace rating plate is followed by an asterisk (*), the furnace has an alternate low-fire only efficiency rating as listed  
in the GAMA and CEC directories. This alternate rating will be listed as the furnace model number followed by an (-L) suffix.  
—16—  
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CAUTION: The furnace can operate in the high-fire mode when certain fault conditions occur. The following  
precautions should be taken:  
1. Size gas piping based on the high-fire input.  
2. Check the high-fire input and adjust it per the main literature instructions.  
NEVER assume the high-fire input rate is not important for low-fire-only installation.  
PROCEDURE 3—FURNACE LOCATION RELATIVE TO COOLINGEQUIPMENT  
The cooling coil must be installed parallel with or on downstream side of furnace to avoid condensation in heat exchanger. When installed parallel  
with a furnace, dampers or other means used to control flow of air must prevent chilled air from entering furnace. If dampers are manually operated,  
they must be equipped with a means to prevent operation of either unit unless the damper is in full-heat or full-cool position.  
PROCEDURE 4—HAZARDOUS LOCATIONS  
18-IN. (457.2 mm)  
MINIMUM TO BURNERS  
A93044  
Fig. 16—Installation in a Garage  
WARNING: When the furnace is installed in a residential garage, the burners and ignition sources must be located at  
least 18 in. above the floor. The furnace must be located or protected to avoid physical damage by vehicles. When the furnace  
is installed in a public garage, airplane hangar, or other building having a hazardous atmosphere, the furnace must be  
installed in accordance with the National Fire Protection Association, Inc. requirements. (See Fig. 16.)  
INSTALLATION  
PROCEDURE 1—LEVELING LEGS (IF DESIRED)  
When furnace is used in upflow position with side inlet(s), leveling legs may be desired. (See Fig. 17.) Install field-supplied, corrosion-resistant  
5/16-in. machine bolts and nuts.  
NOTE: The maximum length of bolt should not exceed 1-1/2 in.  
1. Position furnace on its back. Locate and drill a 5/16-in. diameter hole in each bottom corner of furnace. (See Fig. 17.) Holes in bottom  
closure panel may be used as guide locations.  
2. For each hole, install nut on bolt and then install bolt and nut in hole. (Install flat washer if desired.)  
3. Install another nut on other side of furnace base. (Install flat washer if desired.)  
4. Adjust outside nut to provide desired height, and tighten inside nut to secure arrangement.  
NOTE: Bottom closure must be used when leveling legs are used. See Bottom Closure Panel section.  
PROCEDURE 2—INSTALLATION IN UPFLOW AND DOWNFLOW APPLICATIONS  
NOTE: For downflow applications, this furnace is approved for use on combustible flooring when special base (available from manufacturer) Part  
No. KGASB0201 ALL is used. Special base is not required when this furnace is installed on manufacturer’s Coil Assembly Part No. CD5 or CK5,  
or Coil Box Part No. KCAKC is used.  
1. Determine application being installed from Table 1.  
2. Construct hole in floor per dimensions specified in Table 1 and Fig. 18.  
3. Construct plenum to dimensions specified in Table 1 and Fig. 18.  
4. If downflow subbase (KGASB) is used, install as shown in Fig. 19. If Coil Assembly Part No. CD5 or CK5 or Coil Box Part No. KCAKC  
is used, install as shown in Fig. 20.  
—17—  
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Table 1—Opening Dimensions (in.)  
PLENUM OPENING  
FURNACE  
CASING  
WIDTH  
FLOOR OPENING  
APPLICATION  
A
B
C
D
Upflow Applications  
Downflow Applications on Non-Combustible Flooring  
16  
15-7/8  
24-1/8  
19  
16-5/8  
16-1/2  
24-3/4  
19-5/8  
Downflow Applications on Combustible Flooring Using KGASB  
Subbase  
Furnace with or without CD5 or CK5 Coil Assembly or KCAKC  
Coil Box  
15-1/8  
15-1/2  
19  
19  
16-3/4  
16-1/2  
20-3/8  
20  
17-1/2  
Downflow Applications on Combustible Flooring NOT Using  
KGASB Subbase  
Furnace with or without CD5 or CK5 Coil Assembly or KCAKC  
Coil Box  
Upflow Applications  
Downflow Applications on Non-Combustible Flooring  
19-1/2  
19-3/8  
24-1/8  
19  
20-1/8  
20  
24-3/4  
19-5/8  
Downflow Applications on Combustible Flooring Using KGASB  
Subbase  
Furnace with or without CD5 or CK5 Coil Assembly or KCAKC  
Coil Box  
18-5/8  
19  
19  
19  
20-1/4  
20  
20-3/8  
20  
21  
Downflow Applications on Combustible Flooring NOT Using  
KGASB Subbase  
Furnace with or without CD5 or CK5 Coil Assembly or KCAKC  
Coil Box  
Upflow Applications  
Downflow Applications on Non-Combustible Flooring  
23  
22-7/8  
24-1/8  
19  
23-5/8  
23-1/2  
24-3/4  
19-5/8  
Downflow Applications on Combustible Flooring Using KGASB  
Subbase  
Furnace with or without CD5 or CK5 Coil Assembly or KCAKC  
Coil Box  
22-1/8  
22-1/2  
19  
19  
23-3/4  
23-1/2  
20-3/8  
20  
24-1/2  
Downflow Applications on Combustible Flooring NOT Using  
KGASB Subbase  
Furnace with or without CD5 or CK5 Coil Assembly or KCAKC  
Coil Box  
5/  
16″  
(8mm)  
(8mm)  
5/  
16″  
1 3/4″  
(44mm)  
1 3/4″  
(44mm)  
(8mm)  
5/16″  
(8mm)  
5/  
16″  
(44mm)1 3/4″  
1 3/4″  
(44mm)  
A89014  
Fig. 17—Leveling Legs  
—18—  
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A
PLENUM  
OPENING  
B
D
FLOOR  
OPENING  
C
A96283  
Fig. 18—Floor and Plenum Opening Dimensions  
FURNACE  
(OR COIL CASING  
WHEN USED)  
COMBUSTIBLE  
FLOORING  
DOWNFLOW  
SUBBASE  
SHEET METAL  
PLENUM  
FLOOR  
OPENING  
A96285  
Fig. 19—Furnace, Plenum, and Subbase Installed  
on a Combustible Floor  
NOTE: Remove furnace perforated, supply-air duct flanges when they interfere with mating flanges on coil or downflow subbase. To remove  
perforated, supply-air duct flanges, use wide duct pliers, duct flange tool, or hand seamers to bend flange back and forth until it breaks off. Be  
careful of sharp edges. (See Fig. 21.)  
WARNING: Do not bend duct flanges inward as shown in Fig. 21. This will affect airflow across heat exchangers and  
may cause limit cycling or premature heat exchanger failure. Remove duct flange completely or bend it inward a minimum  
of 210° as shown in Fig. 21.  
PROCEDURE 3—INSTALLATION IN HORIZONTAL APPLICATIONS  
These furnaces can be installed horizontally in either horizontal left or right discharge position. In a crawlspace, the furnace can either be hung  
from floor joist or installed on suitable blocks or pad. Furnace can be suspended from each corner by hanger bolts and angle iron supports. (See  
Fig. 22.) Cut hanger bolts (4 each 3/8-in. all-thread rod) to desired length. Use 1 X 3/8-in. flat washers, 3/8-in. lock washers, and 3/8-in. nuts on  
hanger rods as shown in Fig. 22. Dimples are provided for hole locations. (See Fig. 2.)  
—19—  
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FURNACE  
CD5 OR CK5  
COIL ASSEMBLY  
OR KCAKC  
COIL BOX  
COMBUSTIBLE  
FLOORING  
SHEET METAL  
PLENUM  
FLOOR  
OPENING  
A96284  
Fig. 20—Furnace, Plenum, and Coil Assembly or  
Coil Box Installed on a Combustible Floor  
PERFORATED  
DISCHARGE DUCT  
FLANGE  
NO  
YES  
210 DEG.  
MIN  
YES  
A93029  
Fig. 21—Duct Flanges  
CAUTION: The entire length of furnace MUST be supported when furnace is used in a horizontal position to ensure  
proper draining. When suspended, bottom brace supports sides and center blower shelf. When unit is supported from the  
ground, blocks or pad should support sides and center blower shelf area.  
PROCEDURE 4—AIR DUCTS  
A. General Requirements  
The duct system should be designed and sized according to accepted national standards such as those published by: Air Conditioning Contractors  
Association (ACCA), Sheet Metal and Air Conditioning Contractors National Association (SMACNA) or American Society of Heating,  
Refrigerating and Air Conditioning Engineers (ASHRAE), or consult The Air Systems Design Guidelines reference tables available from your  
local distributor. The duct system should be sized to handle the required system design CFM at the design static pressure.  
When a furnace is installed so that the supply ducts carry air to areas outside the space containing the furnace, the return air must also be handled  
by a duct(s) sealed to the furnace casing and terminating outside the space containing the furnace.  
Secure ductwork with proper fasteners for type of ductwork used. Seal supply- and return-duct connections to furnace with code approved tape  
or duct sealer.  
Flexible connections should be used between ductwork and furnace to prevent transmission of vibration. Ductwork passing through unconditioned  
space should be insulated to enhance system performance. When air conditioning is used, a vapor barrier is recommended.  
—20—  
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COMBUSTION-AIR INTAKE  
(NON-DIRECT VENT/1-PIPE  
APPLICATION)  
COMBUSTION-AIR PIPE  
(DIRECT VENT/2-PIPE  
APPLICATION,ALL SIZES)  
VENT  
3-IN. MINIMUM CLEARANCE TO  
COMBUSTION-AIR INTAKE IS REQUIRED  
(NON-DIRECT VENT/1-PIPE  
APPLICATION,)  
3/8-IN. (10mm) ROD  
ANGLE  
IRON OR  
EQUIVALENT  
3
5
/4″ (146mm)  
ALTERNATE SUPPORT  
LOCATION 4-IN. (102mm) MIN  
8-IN. (203mm) MAX  
(B)  
(A)  
DRAIN  
(B)  
(A)  
(B)  
(A) ROD LOCATION  
USING DIMPLE  
LOCATORS  
13/16-IN. (21mm) MAX  
ALTERNATE SUPPORT  
LOCATION FROM BACK  
3/8-IN. HEX NUT  
& WASHER (4)  
REQD PER ROD  
(A)  
(B)  
(SEE DIMENSIONAL  
DWG FOR  
LOCATIONS)  
NOTES:  
1. A 1 In. (25mm) clearance minimum between  
top of furnace and combustible material.  
(A) PREFERRED ROD LOCATION  
(B) ALTERNATE ROD LOCATION  
2. The entire length of furnace must be  
supported when furnace is used in horizontal  
position to ensure proper drainage.  
3. For non-direct vent/1-pipe application,  
bottom side combustion-air entry cannot be  
used when furnace is installed with hangers  
as shown.  
A93304  
Fig. 22—Crawlspace Horizontal Application  
Maintain a 1-in. clearance from combustible materials to supply air ductwork for a distance of 36 in. horizontally from the furnace. See NFPA  
90B or local code for further requirements.  
B. Ductwork Acoustical Treatment  
Metal duct systems that do not have a 90 degree elbow and 10 ft of main duct to the first branch take-off may require internal acoustical lining.  
As an alternative, fibrous ductwork may be used if constructed and installed in accordance with the latest edition of SMACNA construction  
standard on fibrous glass ducts. Both acoustical lining and fibrous ductwork shall comply with NFPA 90B as tested by UL Standard 181 for Class  
1 Rigid air ducts.  
C. Supply Air Connections  
UPFLOW FURNACES  
Connect supply-air duct to 3/4-in. flange on furnace supply-air outlet. The supply-air duct attachment must ONLY be connected to furnace  
supply-/outlet-air duct flanges or air conditioning coil casing (when used). DO NOT cut main furnace casing to attach supply side air duct,  
humidifier, or other accessories. All accessories MUST be connected external to furnace main casing.  
DOWNFLOW FURNACES  
Connect supply-air duct to supply-air opening on furnace. The supply-air duct attachment must ONLY be connected to furnace supply/outlet or  
air conditioning coil casing (when used), when installed on non-combustible material. When installed on combustible material, supply-air duct  
attachment must ONLY be connected to an accessory subbase or factory approved air conditioning coil casing. DO NOT cut main furnace casing  
to attach supply side air duct, humidifier, or other accessories. All accessories MUST be connected external to furnace main casing.  
HORIZONTAL FURNACES  
Connect supply-air duct to supply air opening on furnace. The supply-air duct attachment must ONLY be connected to furnace supply/outlet or  
air conditioning coil casing (when used). DO NOT cut main furnace casing to attach supply side air duct, humidifier, or other accessories. All  
accessories MUST be connected external to furnace main casing.  
D. Return Air Connections  
UPFLOW FURNACES  
The return-air duct must be connected to bottom, sides (left or right), or a combination of bottom and side(s) of main furnace casing. Bypass  
humidifier may be attached into unused side return air portion of the furnace casing. DO NOT connect any portion of return-air duct to back of  
furnace casing.  
DOWNFLOW AND HORIZONTAL FURNACES  
The return-air duct must be connected to return-air opening provided. DO NOT cut into casing sides or back to attach any portion of return-air  
duct. Bypass humidifier connections should be made at ductwork or coil casing sides exterior to furnace.  
—21—  
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PROCEDURE 5—FILTER ARRANGEMENT  
WARNING: Never operate unit without a filter or with filter access door removed. Failure to follow this warning can  
cause fire, personal injury, or death.  
The air filter arrangement will vary due to application, furnace orientation, and filter type. The filter may be installed in an external Filter/Media  
cabinet (if provided) or the furnace blower compartment. Factory supplied washable filters are shipped in the blower compartment.  
If a factory-supplied external Filter/Media cabinet is provided, instructions for its application, assembly, and installation are packaged with the  
cabinet. The Filter/Media cabinet can be used with the factory-supplied washable filter or a factory-specified high-efficiency disposable filter (see  
cabinet instructions).  
If installing the filter in the furnace blower compartment, determine location for filter and relocate filter retaining wire if necessary. See Table 2  
to determine correct filter size for desired filter location. Table 2 indicates filter size, location, and quantity shipped with this furnace. See Fig.  
2 for location and size of bottom and side return-air openings.  
Table 2—Filter Information  
AIR FILTER LOCATED IN BLOWER COMPARTMENT  
FURNACE  
CASING  
WIDTH (IN.)  
FILTER SIZE (IN.)*  
FILTER  
TYPE  
Side Return  
Bottom Return  
17-1/2  
21  
24-1/2  
(1) 16 X 25 X 1†  
(1) 16 X 25 X 1  
(1 or 2) 16 X 25 X 1  
(1) 16 X 25 X 1†  
(1) 20 X 25 X 1†  
(1) 24 X 25 X 1†  
Cleanable  
Cleanable  
Cleanable  
* Filters may be field modified by cutting filter material and support rods (3) in filters. Alternate sizes and additional filters may be ordered from your dealer.  
† Factory-provided with furnace.  
CAUTION: Use care when cutting support rods in filters to protect against flying pieces and sharp rod ends. Wear  
safety glasses, gloves, and appropriate protective clothing. Failure to follow this caution could result in personal injury.  
CAUTION: For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific use  
of single side inlets. The use of both side inlets, a combination of 1 side and the bottom, or the bottom only will ensure  
adequate return air openings for airflow requirements above 1800 CFM.  
NOTE: Side return-air openings can ONLY be used in UPFLOW configurations. Install filter(s) as shown in Fig. 23.  
For bottom return-air applications, filter may need to be cut to fit some furnace widths. Install filter as shown in Fig. 24.  
NOTE: Remove and discard bottom closure panel when bottom inlet is used.  
WASHABLE  
FILTER  
FILTER  
RETAINER  
A93045  
Fig. 23—Filter Installed for Side Inlet  
PROCEDURE 6—BOTTOM CLOSURE PANEL  
These furnaces are shipped with bottom enclosure panel installed in bottom return-air opening. This panel MUST be in place when side return air  
is used.  
To remove bottom closure panel, perform the following:  
1. Tilt or raise furnace and remove 2 screws holding front filler panel. (See Fig. 25.)  
2. Rotate front filler panel downward to release holding tabs.  
3. Remove bottom closure panel.  
4. Reinstall front filler panel and screws.  
PROCEDURE 7—GAS PIPING  
Gas piping must be installed in accordance with national and local codes. Refer to current edition of NFGC in the United States.  
Canadian installations must be made in accordance with NSCNGPIC and all authorities having jurisdiction.  
Gas supply line should be a separate line running directly from meter to furnace, if possible. Refer to Table 3 for recommended gas pipe sizing.  
—22—  
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21-IN. WIDE  
1712-IN. WIDE  
CASINGS ONLY:  
CASINGS ONLY:  
SUPPORT RODS (3)  
EXTEND 1/4" ON EACH  
SIDE OF FILTER AND  
REST ON CASING FLANGE  
INSTALL FIELD-SUPPLIED  
FILTER FILLER STRIP  
UNDER FILTER.  
3″  
1
24 / ″  
2
1″  
WASHABLE  
FILTER  
FILTER  
RETAINER  
FILTER  
SUPPORT  
A00290  
Fig. 24—Bottom Filter Arrangement  
BOTTOM  
CLOSURE  
PANEL  
FRONT FILLER  
PANEL  
A93047  
Fig. 25—Removing Bottom Closure Panel  
—23—  
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Table 3—Maximum Capacity of Pipe*  
LENGTH OF PIPE (FT)  
NOMINAL  
IRON  
PIPE  
INTERNAL  
DIAMETER  
(IN.)  
SIZE  
10  
20  
30  
40  
50  
(IN.)  
1/2  
3/4  
1
1-1/4  
1-1/2  
0.622  
0.824  
1.049  
1.380  
1.610  
175  
360  
680  
1400  
2100  
120  
250  
465  
950  
1460  
97  
200  
375  
770  
1180  
82  
73  
170  
320  
660  
990  
151  
285  
580  
900  
* Cubic ft of gas per hr. for gas pressures of 0.5 psig (14–in. wc) or less and a pressure drop of 0.5–in wc (based on a 0.60 specific gravity gas).  
Ref: NFGC.  
Risers must be used to connect to furnace and to meter. Support all gas piping with appropriate straps, hangers, etc. Use a minimum of 1 hanger  
every 6 ft. Joint compound (pipe dope) should be applied sparingly and only to male threads of joints. Pipe dope must be resistant to propane gas.  
CAUTION: Connect gas pipe to furnace using a backup wrench to avoid damaging gas controls.  
WARNING: Gas valve shutoff switch MUST be facing forward or tilted upward. Failure to follow this warning could  
result in property damage or death.  
WARNING: Never purge a gas line into a combustion chamber. Never use matches, candles, flame, or other sources  
of ignition for purpose of checking leakage. Use a soap-and-water solution to check for leakage. Failure to follow this warning  
could result in fire, explosion, personal injury, or death.  
WARNING: Use proper length of pipe to avoid stress on gas control manifold. Failure to follow this warning could  
result in a gas leak resulting in fire, explosion, personal injury, or death.  
Install a sediment trap in riser leading to furnace. Trap can be installed by connecting a tee to riser leading to furnace so straight-through section  
of tee is vertical. Then connect a capped nipple into lower end of tee. Capped nipple should extend below level of gas controls. Place a ground  
joint union between gas control manifold and manual gas shutoff valve. (See Fig. 26.)  
GAS  
SUPPLY  
MANUAL  
SHUTOFF  
VALVE  
(REQUIRED)  
SEDIMENT  
TRAP  
UNION  
A93324  
Fig. 26—Typical Gas Pipe Arrangement  
CAUTION: If a flexible connector is required or allowed by authority having jurisdiction, black iron pipe shall be  
installed at gas valve and extend a minimum of 2 in. outside furnace casing.  
An accessible manual shutoff valve MUST be installed upstream of furnace gas controls and within 6 ft of furnace. A 1/8-in. NPT plugged tapping,  
accessible for test gage connection, MUST be installed immediately upstream of gas supply connection to furnace and downstream of manual  
shutoff valve.  
—24—  
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NOTE: The gas valve inlet press tap connection is suitable to use as test gage connection providing test pressure DOES NOT exceed maximum  
0.5 psig (14-in. wc) stated on gas valve. (See Fig. 56.) Piping should be pressure tested in accordance with NFGC local and national plumbing  
and gas codes before furnace is attached. In Canada, refer to current edition of NSCNGPIC. If pressure exceeds 0.5 psig (14-in. wc), gas supply  
pipe must be disconnected from furnace and capped before pressure test. If test pressure is equal to or less than 0.5 psig (14-in. wc), turn off electric  
shutoff switch located on gas valve before test. It is recommended that ground joint union be loosened before pressure testing. After all connections  
have been made, purge lines and check for leakage.  
FIELD 24-V WIRING  
FIELD 115-, 208/230-, 460-V WIRING  
FACTORY 24-V WIRING  
FACTORY 115-, 208/230-, 460-V WIRING  
NOTE 5  
THERMOSTAT  
TERMINALS  
W
C
R
G
Y
FIVE  
WIRE  
FIELD-SUPPLIED  
DISCONNECT  
THREE-WIRE  
HEATING  
ONLY  
208/230- OR  
460-V  
THREE PHASE  
W/W1  
GND  
GND  
GND  
115-V  
SINGLE  
PHASE  
NOTE  
3
W2  
R
208/230-V  
SINGLE  
PHASE  
G
C
AUXILIARY  
J-BOX  
115-V  
FIELD-SUPPLIED  
DISCONNECT  
SWITCH  
GND  
NOTE 1  
CONDENSING  
UNIT  
Y/Y2  
TWO WIRE  
NOTES:  
24-V  
TERMINAL  
BLOCK  
FURNACE  
CONTROL  
CENTER  
1. Connect Y or Y/Y2 terminal as shown for proper cooling operation.  
2. Proper polarity must be maintained for 115-v wiring.  
3. Use W2 with 2-stage thermostat when zoning.  
4. If any of the original wire, as supplied, must be replaced, use  
same type or equivalent wire.  
5. Some thermostats require a "C" terminal connection as shown.  
A98325  
Fig. 27—Heating and Cooling Application Wiring Diagram  
PROCEDURE 8—ELECTRICAL CONNECTIONS  
See Fig. 27 for field wiring diagram showing typical field 115-v and 24-v wiring. Check all factory and field electrical connections for tightness.  
WARNING: Blower access panel door switch opens 115-v power to control center. No component operation can  
occur. Do not bypass or close switch with panel removed. Failure to follow this warning could result in personal injury or  
death.  
CAUTION: Furnace control must be grounded for proper operation or control will lock out. Control is grounded  
through green wire routed to gas valve and burner box screw.  
A. 115-V Wiring  
Before proceeding with electrical connections, make certain that voltage, frequency, and phase correspond to that specified on the furnace rating  
plate. Also, check to be sure that service provided by utility is sufficient to handle load imposed by this equipment. Refer to rating plate or Table  
4 for equipment electrical specifications.  
Make all electrical connections in accordance with National Electrical Code (NEC) ANSI/NFPA 70-2002 and any local codes or ordinances that  
might apply. For Canadian installations, all electrical connections must be made in accordance with Canadian Electrical Code CSA C22.1 or  
authorities having jurisdiction.  
Use a separate, fused branch electrical circuit containing a properly sized fuse or circuit breaker for this furnace. See Table 4 for wire size and  
fuse specifications. A disconnecting means must be located within sight from and readily accessible to furnace.  
NOTE: Proper polarity must be maintained for 115-v wiring. If polarity is incorrect, control LED status indicator light will flash rapidly and  
furnace will NOT operate.  
—25—  
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Table 4—Electrical Data  
OPERATING  
VOLTS—  
HERTZ—  
PHASE  
MAX  
MIN  
WIRE  
SIZE  
MAX WIRE  
LENGTH  
(FT)‡  
MAX FUSE  
OR CKT BKR  
AMPS**  
UNIT  
SIZE  
UNIT  
VOLTAGE RANGE  
UNIT  
AMPACITY†  
AMPS  
Max*  
127  
127  
127  
127  
127  
127  
Min*  
104  
104  
104  
104  
104  
104  
042040  
042060  
042080  
060080  
060100  
060120  
115-60-1  
115-60-1  
115-60-1  
115-60-1  
115-60-1  
115-60-1  
8.9  
8.9  
8.9  
13.8  
13.8  
11.6  
12.0  
12.0  
12.0  
17.9  
18.1  
15.3  
14  
14  
14  
12  
12  
12  
31  
31  
31  
32  
32  
37  
15  
15  
15  
20  
20  
20  
* Permissible limits of voltage range at which unit will operate satisfactorily.  
† Unit ampacity = 125 percent of largest operating component’s full load amps plus 100 percent of all other potential operating components’ (EAC, humidifier, etc.) full load  
amps.  
‡ Length shown is a measured 1 way along wire path between unit and service panel for maximum 2 percent voltage drop.  
** Time-delay type is recommended.  
ELECTRIC  
DISCONNECT  
SWITCH  
COPPER  
WIRE ONLY  
ALUMINUM  
WIRE  
A93033  
Fig. 28—Disconnect Switch and Furnace  
CAUTION: Do not connect aluminum wire between disconnect switch and furnace. Use only copper wire. (See Fig. 28.)  
WARNING: The furnace casing MUST have an uninterrupted or unbroken ground according to NEC ANSI/NFPA  
70-2002 and Canadian Electrical Code CSA C22.1 or local codes to minimize personal injury if an electrical fault should occur.  
This may consist of electrical wire or conduit approved for electrical ground when installed in accordance with existing  
electrical codes. Do not use gas piping as an electrical ground. Failure to follow this warning could result in electrical shock,  
fire, or death.  
J-BOX RELOCATION  
1. Remove 2 screws holding auxiliary J-box. (See Fig. 29.)  
2. Rotate J-box 180° and attach box to left side, using holes provided.  
CAUTION: If manual disconnect switch is to be mounted on furnace, select a location where a drill or fastener will not  
contact electrical or gas components.  
B. 24-V Wiring  
Make field 24-v thermostat connections at 24-v terminal block on control center. Y wire from thermostat MUST be connected to Y terminal on  
control center, as shown in Fig. 27, for proper cooling operation. The 24-v terminal board is marked for easy connection of field wiring. (See Fig.  
30.) The 24-v circuit contains a 3-amp, automotive-type fuse located on control center. (See Fig. 31.) Any electrical shorts of 24-v wiring during  
installation, service, or maintenance may cause fuse to blow. If fuse replacement is required, use only a fuse of identical size (3 amp).  
NOTE: Use AWG No. 18 color-coded copper thermostat wire for lengths up to 100 ft. For wire lengths over 100 ft, use AWG No. 16 wire.  
NOTE: For 2-speed applications, refer to Sequence of Operation section.  
C. Accessories  
1. Electronic Air Cleaner (EAC)  
The control center EAC terminals are energized with 115v (1.5-amp maximum) during blower operation.  
a. Two extension leads are connected to the control center EAC terminals to assist field installation of an EAC. (See Fig. 31.) To use these  
leads, proceed with the following:  
(1.) Strip EAC power lead insulation approximately 1/4 in.  
(2.) Insert stripped end into factory-supplied black lead’s butt connector and crimp to secure.  
(3.) Strip EAC neutral lead insulation approximately 1/4 in.  
(4.) Insert stripped end into factory-supplied white leads’s butt connector and crimp to secure.  
—26—  
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ALTERNATE  
FIELD  
LOCATION  
FACTORY  
INSTALLED  
LOCATION  
A00212  
Fig. 29—Relocating J-Box  
NOTE: If desired, cut butt connectors off factory leads and strip insulation approximately 1/4 in and use field-supplied wire nuts to connect.  
b. An alternate method to attach EAC lead to control center is the following procedure:  
(1.) Remove 2 screws securing the control box to furnace blower shelf.  
(2.) Remove and discard 2 factory-supplied leads from control center EAC terminals.  
(3.) Strip EAC power leads insulation approximately 1/8 in.  
NOTE: The control center EAC terminals are sized for 12 gage maximum, solid or stranded wire.  
(4.) Route EAC leads through right-hand wire grommet.  
(5.) Insert EAC stripped leads into control center EAC terminals by depressing terminal’s arm with a screwdriver or finger. (See Fig.  
32.)  
(6.) Reinstall control box to furnace blower shelf using 2 screws removed earlier.  
2. Humidifier (HUM)  
Screw terminals (HUM and COM) are provided for 24-v humidifier connection. (See Fig. 30.) The HUM terminal is energized with 24-v  
(0.5-amp maximum) after inducer motor prepurge period.  
NOTE: A field-supplied, 115–v controlled relay connected to EAC terminals may be added if humidifier operation is desired during blower  
operation.  
3. Dehumidification (DEHUM)  
A dehumidification input is provided via a 1/4-in. male quick-connect labeled DEHUM located next to the transformer secondary  
connections. When there is a dehumidify demand, the DEHUM input is activated, which means 24 vac signal is removed from the DEHUM  
input terminal. In other words, the DEHUM input logic is reversed. the DEHUM input is turned ON when no dehumidify demand exists  
and is turned OFF when demand exists. This logic reversal has come about from historical use of a standard humidistat to do  
dehumidification since the contacts open on high humidity, thus removing the 24-v signal to initiate dehumidification.  
The DEHUM output on the thermidistat control or the humidistat output is connected directly to the DEHUM terminal on the furnace  
control. In addition, the DE jumper located next to the DEHUM terminal must be removed to enable the DEHUM input. (See Fig. 33 and  
34.) When a dehumidify demand exists, the furnace control reduces the blower airflow by 21 percent to 315 CFM per ton during continuous  
fan or cooling operation.  
PROCEDURE 9—DIRECT VENTING  
The 355MAV furnaces require a dedicated (one 355MAV furnace only) direct-vent system. In a direct-vent system, all air for combustion is taken  
directly from outside atmosphere, and all flue products are discharged to outside atmosphere.  
A. Removal of Existing Furnaces from Common Vent Systems  
If furnace being replaced was connected to a common vent system with other appliances, the following steps shall be followed with each appliance  
connected to the venting system placed in operation, while any other appliances connected to the venting system are not in operation:  
1. Seal any unused openings in the venting system.  
2. Inspect the venting system for proper size and horizontal pitch as required in the National Fuel Gas Code, ANSI Z223.1 or 24 the CAN/CGA  
B149 Installation Codes and these instructions. Determine that there is no blockage or restriction, leakage, corrosion, and other deficiencies  
which could cause an unsafe condition.  
3. If practical, close all building doors and windows and all doors between the space in which the appliance(s) connected to the venting system  
are located and other spaces of the building. Turn on clothes dryers and any appliance not connected to the venting system. Turn on any  
exhaust fans, such as range hoods and bathroom exhausts, so they shall operate at maximum speed. Do not operate a summer exhaust fan.  
Close fireplace dampers.  
—27—  
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MODEL  
SIZE  
TO 115 VAC FIELD DISCONNECT  
L2  
NOTE #2  
JUMPERS  
1-4 2-5 3-6  
X
FUSED DISCONNECT SWITCH  
(WHEN REQ’D)  
SCHEMATIC DIAGRAM  
L1  
NOTE #2  
ILK  
EQUIPMENT GROUND  
042040  
042060  
042080  
060100  
060080  
060120  
(NATURAL GAS & PROPANE)  
L2  
FU2  
X
X
MTR1  
HSI  
BLK  
BLK  
WHT  
X
X
WHT  
T 2  
T 1  
ILK  
PL9  
FSE  
12  
6
X
X
X
L1  
1
2
1
2
10  
4
12  
6
GND  
4
X
MTR1  
PL7  
2
RED  
FRS  
LS  
ALS  
1
6
5
4
10  
BLU  
3
PL1  
PL7  
WHT  
TRAN  
HPS  
LPS  
GV  
BLK  
NO  
C
D.C.  
P
POWER  
SUPPLY  
PCB  
C
L1  
L2  
P1  
P2  
B1  
B2  
NOTE #5  
BLU  
BRN  
NOTE #11  
NO  
CPU1  
CPU2  
1.5 AMP  
T 1  
T 2  
M
2
1
YEL  
SW - 4  
EMER. HEAT  
C
HI  
ORN  
BRN  
PL4  
8
PL2  
GRN/YEL  
ORN  
NOTE #11  
PL13  
6
14  
8
16  
3
1 2  
3
4
1
7
10 11  
3
3
2
GRN / YEL  
NOTE #3  
5
4
3
2
1
HUM  
LGPS  
1
2
3
4
5
PL3  
PL1  
ORN  
9
4
G
R
5
6
(WHEN  
USED)  
RED  
Y/Y2  
BLK  
W/W1  
WHT  
SEC-2  
BRN  
C
OM  
MTR2  
PL11  
IND  
PL11  
PL12  
5
DE  
W2  
B1  
7
6
5
4
3
2
1
BLU  
NOTE #7  
SEC-1  
DEHUM  
9
8
7
1
6
5
4
3
2
1
PL3  
RED  
FUSE  
PL10  
PL11  
NOTE  
#6  
BLOWER  
PL10  
FU1  
LEDS  
(1-4)  
A/C AND CF  
SELECT. CHART  
A/C CF  
A/C AND CF  
SWITCH  
POS.  
SWITCH  
POS.  
24VAC-3A  
SELECT. CHART  
OFF-DELAY  
1
2
3
4
A/C  
SELECTION CHART  
A/C  
3
TON  
3-1/2  
TON  
CF  
1
2
3
3
3
3
1
2
3
B2  
CF  
7 8  
90  
1200  
CFM  
1400  
CFM  
5
DEFAULT DEFAULT  
1 2 3  
1 2 3  
OFF  
2
HSIR  
OFF  
SEC.  
2
1
2
1
OFF  
7 8  
1
5
1
2
3
1
PL11  
1
1-1/2  
TON  
2
600  
CFM  
800  
PL4  
PL9  
HSI  
1 2 3 4 5 6 7 8  
135  
SW  
(1-8)  
OFF  
OFF  
EAC  
SEC.  
EAC-1 EAC-2  
PL12  
RED  
1
2
1
2
3
OFF  
7 8  
4
TON  
5
1600  
CFM  
2000  
CFM  
2
4
3
P1  
P2  
115VAC  
TRAN  
TON  
CFM  
180  
3
16  
8
OFF  
2
OFF  
FU1  
PL1-9  
ORN  
1
2
3
1
2-1/2  
TON  
1000  
CFM  
SEC.  
OFF  
7 8  
VIO  
MTR2  
TON  
24VAC  
YEL  
BLU  
OFF  
OFF  
225  
NOTE #6  
PL1-11  
SEC-1  
14  
6
SEC-2  
ALS  
LS  
3
6
2
5
1
4
FRS  
PCB  
PL6  
1
SEC.  
PL5  
PL13  
OFF  
LEGEND  
A/C  
ALS  
CF  
AIR CONDITIONING (ADJUSTABLE TONNAGE)  
DEHUM  
PL6  
PL7  
PL9  
3-CIRCUIT COMM. CONNECTOR  
12-CIRCUIT INDUCER MTR CONNECTOR  
2-CIRCUIT HSI CONNECTOR  
HUMR  
AUXILIARY LIMIT SWTICH OVERTEMP - MANUAL RESET SPST-(N.C)  
CONTINUOUS FAN (ADJUSTABLE CFM)  
MAIN MICROPROCESSOR & CIRCUITRY  
IGNITION MICROPROCESSOR & CIRCUITRY  
DEHUMIDIFY ENABLE - IF DE CONNECTION PROVIDED REMOVE  
JUMPER TO ENABLE DEHUM INPUT  
HUM  
DE  
(WHEN USED)  
CPU1  
CPU2  
DE  
R
G
GV  
PL10  
PL11  
PL12  
PL13  
SW1  
SW2  
SW3  
SW4  
SW5  
SW6  
9-CIRCUIT BLOWER ADAPTER CONNECTOR  
1-CIRCUIT INDUCTOR SPLICE CONNECTOR  
5-CIRCUIT BLOWER POWER CONNECTOR  
16-CIRCUIT BLOWER CTRL. CONNECTOR  
MANUAL SWITCH, FAULT DISPLAY, SPST-(N.O.)  
MANUAL SWITCH, LOW HEAT, SPST-(N.O.)  
MANUAL SWITCH, BYPASS HUMIDIFIER, SPST-(N.O.)  
MANUAL SWITCH, EMERGENCY HEAT, SPST-(N.O.)  
MANUAL SWITCH, MULTIPLE ZONE, SPST-(N.O.)  
COMPONENT TEST, SPST-(N.O.)  
PCB  
NOTE #5  
P
D.C. POWER  
SUPPLY  
GVR  
PL1-7  
PL1-2  
C
DEHUM  
EAC-1  
EAC-2  
FRS  
DEHUMIDIFICATION CONNECTION (24VAC .02 AMPS)  
ELECTRONIC AIR CLEANER CONNECTION (115 VAC 1.5 AMP MAX.)  
ELECTRONIC AIR CLEANER CONNECTION (COMMON)  
FLAME ROLLOUT SWITCH - MANUAL RESET, SPST-(N.C.)  
FLAME PROVING SENSOR ELECTRODE  
FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED  
FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE  
(FIELD INSTALLED & SUPPLIED)  
Y/Y2  
W2  
M
PL1-10  
PL2-4  
PL2-2  
HI  
CPU1  
NOTE #3  
NO  
FSE  
W/W1  
COM  
HPS  
EAC  
FU1  
C
FU2  
SW7-8 MANUAL SWITCH, BLOWER OFF-DELAY, SPST-(N.O.)  
TRAN TRANSFORMER - 115VAC/24VAC  
GND  
GV  
EQUIPMENT GROUND  
LPS  
LGPS  
NOTE #11  
GAS VALVE  
HUMR  
HSIR  
GVR  
NOTE #11  
NO  
GVR  
HI  
GAS VALVE RELAY, DPST-(N.O.)  
JUNCTION  
C
GAS VALVE HIGH STAGE OPERATOR  
HIGH HEAT PRESSURE SWITCH, SPST-(N.O.)  
HOT SURFACE IGNITOR (115 VAC)  
HPS  
HSI  
(WHEN USED)  
UNMARKED TERMINAL  
CPU2  
PL2-1  
PL1-1  
PCB TERMINAL (FACTORY CONNECTED)  
FACTORY WIRING (115 VAC)  
FACTORY WIRING (24 VAC)  
HSIR  
HUM  
HUMR  
ILK  
HOT SURFACE IGNITOR RELAY, SPST-(N.O.)  
24VAC HUMIDIFIER CONNECTION (.5 AMP. MAX.)  
HUMIDIFIER RELAY, SPST-(N.O.)  
FSE  
BLOWER ACCESS PANEL INTERLOCK SWITCH, SPST-(N.O.)  
INDUCTOR (NOTE #7)  
NOTES:  
IND  
JB  
LEDS  
LGPS  
LPS  
LS  
FIELD WIRING (115 VAC)  
CONDUCTOR ON PCB  
JUNCTION BOX  
1. If any of the original equipment wire is replaced use wire rated for 105°C.  
LIGHT EMITTING DIOES FOR STATUS CODES  
LOW GAS PRESSURE SWITCH, SPST (N.O.)  
LOW HEAT PRESSSURE SWITCH, SPST-(N.O.)  
LIMIT SWITCH, AUTO RESET, (N.C.)  
2. Use only copper wire between the disconnect switch and the furnace junction box (JB).  
3. This wire must be connected to furnace sheet metal for control to prove flame.  
4. Symbols are electrical representation only.  
FIELD WIRING SCREW TERMINAL  
TERMINAL BLOCK - MARKED TERMINAL  
FIELD EARTH GROUND  
MTR1  
MTR2  
PCB  
PL1  
MOTOR (ICM) INDUCER  
5. Solid lines, inside circuit board PCB are printed circuit board traces and are not depicted as shown in the legend.  
6. Replace only with a 3 AMP fuse.  
7. Inductor used on all 060 or -20 airflow units.  
8. Blower-on delay, gas heating 60 seconds low heat, 35 seconds high heat, cooling or heat pump 2 seconds..  
9. Blower-off delay, gas heating 90, 135, 180 or 225 seconds, cooling or heat pump 90 seconds.  
10. Ignition-lockout will occur after four consecutive unsuccessful trials-for-ignition. Control will auto-reset after three hours.  
11. Factory connected when LGPS not used.  
MOTOR (ICM) BLOWER  
PRINTED CIRCUIT BOARD  
EQUIPMENT GROUND  
11-CIRCUIT CONNECTOR  
FIELD SPLICE  
PL2  
4-CIRCUIT PRESSURE SWITCH CONNECTOR  
5-CIRCUIT BLOWER MTR CONNECTOR  
2-CIRCUIT HSI CONNECTOR  
PL3  
PCB TERMINAL (FIELD CONNECTION)  
PLUG RECEPTACLE  
PL4  
PL5  
6-CIRCUIT MODEL PLUG  
322296-101 REV. E  
A00350  
Fig. 30-Unit Wiring Diagram  
—28—  
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HOT SURFACE  
IGNITOR CONNECTOR  
EAC-ELECTRONIC AIR  
CLEANER TERMINALS  
(115-VAC 1 AMP MAX)  
115-V  
CONNECTORS  
PRESSURE SWITCH  
CONNECTOR  
HUM-HUMIDIFIER  
TERMINAL  
(24-VAC 0.5 AMP MAX)  
MAIN BLOWER  
CONTROL WIRE  
CONNECTOR  
24-V THERMOSTAT  
TERMINALS  
DEHUMIDIFY ENABLE (DE)  
TRANSFORMER  
24-V CONNECTORS  
DEHUMIDIFIER (DEHUM)  
CONNECTOR  
3-AMP FUSE  
STATUS AND DIAGNOSTIC  
LED LIGHTS  
AIR CONDITIONING  
(A/C) SETUP SWITCH  
SETUP SWITCHES  
(SW) AND BLOWER  
OFF DELAY SETUP  
SWITCHES  
CONTINUOUS  
FAN (CF) SETUP  
SWITCHES  
MODEL PLUG  
COMMUNICATION  
CONNECTOR  
A99097  
Fig. 31—Control Center  
EAC1  
EAC2  
Fig. 32—EAC Terminals on Control Center  
A93053  
4. Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so appliance shall operate continuously.  
5. Test for draft hood equipped appliance spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the flame of  
a match or candle.  
6. After it has been determined that each appliance connected to the venting system properly vents when tested as outlined above, return doors,  
windows, exhaust fans, fireplace dampers, and any other gas-burning appliance to their previous conditions of use.  
7. If improper venting is observed during any of above tests, the venting system must be corrected.  
Vent system or vent connectors may need to be resized. For any other appliances when resizing vent systems or vent connectors, system or  
connector must be sized to approach minimum size as determined using appropriate table found in the NFGC or NSCNGPIC.  
B. Combustion-Air and Vent Piping  
GENERAL  
Combustion-air and vent pipe, fittings, primers, and solvents must conform to American National Standards Institute (ANSI) standards and  
American Society for Testing and Materials (ASTM) standards. See Table 6 for approved materials for use in the U.S.A. See Table 7 for maximum  
pipe lengths and Fig. 39, 40, 41, 42, and 43 for exterior piping arrangements.  
In Canada, construct all combustion-air and vent pipes for this unit of CSA or ULC certified schedule-40 PVC, PVC-DWV or ABS-DWV pipe  
and pipe cement. SDR pipe is NOT approved in Canada.  
—29—  
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DE  
DE CONNECTION  
DE CONNECTION  
LOCATION  
A99098  
Fig. 33—355MAV Variable Speed Furnace Control  
VARIABLE-SPEED  
CONDENSING  
FURNACE  
THERMIDISTAT  
R
R
24 VAC HOT  
DEHUMIDIFY DHUM  
DEHUM  
DE  
NOTE 1  
24 VAC COMM  
C
Com  
NOTE 1 - Remove DE Connection  
To Enable DEHUM Input  
A98295  
Fig. 34—Thermidistat Connection  
NOTE: Furnace combustion-air and vent pipe connections are sized for 2-in. pipe. Any pipe size change should be made outside furnace casing  
in vertical pipe. (See Fig. 35.) This allows proper drainage of vent condensate.  
Combustion-air and vent pipes must terminate together in same atmosphere pressure zone, either through roof or sidewall (roof termination  
preferred), using accessory termination kit. See Table 5 for required clearances.  
Furnace combustion-air and vent pipe connections must be attached as shown in Fig. 37. Combustion-air intake plug fitting and inducer housing  
alternate vent cap may need to be relocated in some applications.  
NOTE: Slope combustion-air and vent pipes a minimum of 1/4 in. per linear ft with no sags between hangers.  
CAUTION: When combustion-air pipe is installed above a suspended ceiling, pipe must be insulated with 3/8-in. thick  
Armaflex-type insulation. Combustion-air pipe should also be insulated when it passes through warm, humid space.  
An abandoned masonry chimney may be used as a raceway for properly insulated and supported combustion-air and vent pipes. Each furnace must  
have its own set of combustion-air and vent pipes and be terminated individually, as shown in Fig. 39, 40, 44 and 45.  
—30—  
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FURNACE  
NOT IN  
HORIZONTAL  
SECTION  
PIPE DIAMETER  
TRANSITION IN  
VERTICAL SECTION  
A93034  
Fig. 35—Combustion-Air and Vent Pipe Diameter Transition Location and Elbow Configuration  
Table 5—Combustion-Air and Vent Pipe Termination Clearances  
CLEARANCE (FT)  
LOCATION  
U.S.A.  
Canada  
Above grade level or aboveanticipated snow depth  
Dryer/Water heater ventt  
From plumbing vent stack  
1
3
3
1†  
3
3
From any mechanical fresh air intake  
See note 4  
6
For furnaces with an input capacity of100,000 Btuh or less—from any non-  
mechanical air supply (windows or doorswhich can be opened) or combustion-air  
opening  
For furnaces with an input capacity greaterthan 100,000 Btuh or less—from any non-  
mechanical air supply (windows or doorswhich can be opened) or combustion-air  
opening  
1
1
1
3
From service regulator vent, electric and gas meters and relief equipment  
Above grade when adjacent to public walkway  
4*  
Note 3  
6‡  
Note 3  
* Horizontal distance.  
† 18 in. above roof surface in Canada.  
‡ 36 in. to electric meter in Canada only.  
NOTES:  
1. If installing 2 adjacent 355MAV furnaces, refer to Multiventing and Vent Terminations section for proper vent configurations.  
2. When locating combustion-air and vent terminations, consideration must begiven to prevailing winds, location, and other conditions which may cause  
recirculation of the appliance’s own flue products or the flue products of adjacent vents. Recirculation can cause poor combustion, inlet condensate problems,  
and accelerated corrosion of heat exchangers.  
3. Vent termination can not terminate less than 2 ft horizontal and 7 ft above public walkway or where condensate vapor or droplets may be a hazard.  
4. Vent termination must be at least 3 feet above any forced draft inlets within 10 feet horizontal. Vent termination must be at least 3 feet horizontal from other  
direct vent appliances intake unless otherwise specified by manufacturer.  
Other gas appliances with their own venting system may also use the abandoned chimney as a raceway providing it is permitted by local code,  
the current edition of the National Fuel Gas Code and the vent or liner manufacturer’s installation instructions. Care must be taken to prevent the  
exhaust gases from one appliance from contaminating the combustion air of other gas appliances.  
CAUTION: When vent pipe is exposed to temperatures below freezing, such as when it passes through an unheated  
space or when a chimney is used as a raceway, pipe must be insulated as shown in Table 8 with Armaflex-type insulation.  
—31—  
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Table 6—Approved Combustion-Air and Vent Pipe, Fitting and Cement Materials  
SPECIFICATION  
(MARKED ON MATERIAL)  
MATERIAL PIPE FITTINGS SOLVENT CEMENT AND PRIMERS  
DESCRIPTION  
D1527  
D1785  
ABS  
PVC  
Pipe  
Pipe  
Schedule-40  
Schedule-40  
Solvent  
Cement  
D2235  
For ABS  
For ABS  
D2241  
D2466  
D2468  
PVC  
PVC  
ABS  
Pipe  
Fittings  
Fittings  
SDR-21 & SDR-26  
Schedule-40  
Schedule-40  
Solvent  
Cement  
D2564  
For PVC  
For PVC  
D2661  
D2665  
F438  
F441  
F442  
ABS  
PVC  
CPVC  
CPVC  
CPVC  
Pipe  
Pipe  
Pipe  
Pipe  
Fittings  
Fittings  
Fittings  
DWV at Schedule-40 IPS sizes  
DWV  
Schedule-40  
Schedule-40  
SDR  
Solvent  
Cement  
F493  
For CPVC  
For CPVC  
F628  
F656  
F891  
ABS  
For PVC  
PVC  
Pipe  
Pipe  
Primer  
Cellular Core DWV at Schedule-40 IPS sizes  
For PVC  
Cellular Core Schedule-40 & DWV  
NOTE: Select 1 vent pipe connection and NOTE: Select 1 vent pipe connection and  
1 combustion-air pipe connection.  
1 combustion-air pipe connection.  
AIR  
FLOW  
COMBUSTION-  
AIR  
COMBUSTION-  
AIR  
VENT  
VENT  
VENT  
VENT  
COMBUSTION-  
AIR  
COMBUSTION-  
AIR  
AIR  
FLOW  
UPFLOW  
DOWNFLOW  
COMBUSTION-  
AIR  
COMBUSTION-  
AIR  
VENT  
VENT  
AIR  
FLOW  
AIR  
FLOW  
HORIZONTAL-LEFT DISCHARGE  
HORIZONTAL-RIGHT DISCHARGE  
A96187  
Fig. 36—Combustion-Air and Vent Pipe Connections  
—32—  
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CAUTION: Combustion air must not be taken from inside structure because inside air is frequently contaminated by  
halogens, which include fluorides, chlorides, bromides, and iodides. These elements are found in aerosols, detergents,  
bleaches, cleaning solvents, salts, air fresheners, adhesives, paint, and other household products. Locate combustion-air  
inlet as far as possible from swimming pool and swimming pool pump house. Excessive exposure to contaminated  
combustion air will result in safety and performance related problems  
WARNING: Solvent cements are combustible. Keep away from heat, sparks, and open flame. Use only in well  
ventilated areas. Avoid breathing in vapor or allowing contact with skin or eyes. Failure to follow this warning could result  
in fire, property damage, personal injury, or death.  
WARNING: All combustion-air and vent pipes must be airtight and watertight. Pipes must also terminate exactly as  
shown in Fig. 39, 40, 41, 42, or 43. Failure to follow this warning could result in property damage, personal injury, or death.  
NOTE: The minimum combustion-air and vent pipe length (each) for these furnaces is 5 ft. Short pipe lengths (5-8 ft) may discharge water  
droplets. These droplets may be undesirable, and a 12-in. minimum offset pipe section is recommended, as shown in Fig. 37, to reduce excessive  
droplets from exiting vent pipe outlet.  
12MIN  
(305mm)  
12MIN  
(305mm)  
VENT PIPE  
VENT PIPE  
COMBUSTION-AIR PIPE  
COMBUSTION-AIR PIPE  
HORIZONTAL TO ROOF  
COMBUSTION-AIR PIPE  
HORIZONTAL TO SIDEWALL  
COMBUSTION-AIR PIPE  
VENT PIPE  
12MIN  
(304.8mm)  
12MIN  
(304.8mm)  
VENT PIPE  
VERTICAL TO ROOF  
VERTICAL TO SIDEWALL  
NOTE: A 12-in. (304.8mm) minimum offset pipe section is recommended  
with short (5 to 8 ft / 1.5 to 2.5M) vent systems. This recommendation  
is to reduce excessive condensate droplets.  
A96230  
Fig. 37—Short Vent (5 to 8 ft) System  
COMBUSTION-AIR AND VENT PIPE DIAMETER  
Determine combustion-air and vent pipe diameter.  
1. Using Table 7, individually determine the smallest combustion-air and vent pipe diameters allowed for each pipe. Pick the larger of these  
2 pipe diameters and use this diameter for both combustion-air and vent pipes.  
2. When installing vent systems of short pipe length, use the smallest allowable pipe diameter. Do not use pipe size greater than required or  
incomplete combustion, flame disturbance, or flame sense lockout may occur.  
—33—  
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Table 7—Maximum Allowable Pipe Length (ft)  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
UNIT SIZE  
042040  
1
2
45  
70  
45  
70  
25  
70  
40  
70  
NA  
30  
70  
3
40  
70  
40  
70  
20  
70  
35  
70  
NA  
15  
70  
4
5
6
25  
70  
25  
70  
5
1-1/2  
2
1-1/2  
2
50  
70  
50  
70  
30  
70  
45  
70  
10  
35  
70  
35  
70  
35  
70  
15  
70  
30  
70  
NA  
NA  
70  
30  
70  
30  
70  
10  
70  
25  
70  
NA  
NA  
70  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
1-1/2  
2
2
2-1/2  
2-1/2  
3
042080  
060080  
2 Pipe or 2-in  
Concentric  
0 to 2000  
70  
20  
70  
NA  
NA  
70  
2 Pipe or 2-in  
Concentric  
060100  
2 Pipe or 3-in.  
Concentric  
060120  
3†  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
UNIT SIZE  
042040  
1
2
3
4
30  
70  
30  
70  
11  
70  
25  
70  
NA  
61  
5
25  
70  
25  
70  
6
70  
20  
70  
NA  
61  
6
1–1/2  
45  
70  
45  
70  
26  
70  
40  
70  
31  
63  
40  
70  
40  
70  
21  
70  
35  
70  
26  
62  
35  
70  
35  
70  
16  
70  
30  
70  
12  
62  
20  
70  
20  
70  
NA  
70  
15  
70  
NA  
61  
2 Pipe or 2-in  
Concentric  
2
1–1/2  
2
1–1/2  
2
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
2001 to 3000  
2
2 Pipe or 2-in  
Concentric  
060100  
060120  
2–1/2  
3
2 Pipe or 3-in.  
Concentric  
3†  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
UNIT SIZE  
042040  
1
2
3
4
27  
70  
27  
70  
10  
70  
23  
70  
NA  
57  
5
22  
70  
22  
70  
5
70  
18  
70  
NA  
57  
6
1-1/2  
2
1-1/2  
2
1-1/2  
2
2
2-1/2  
3
3†  
42  
70  
42  
70  
25  
70  
38  
70  
29  
59  
37  
70  
37  
70  
20  
70  
33  
70  
24  
59  
32  
70  
32  
70  
15  
70  
28  
70  
10  
58  
17  
70  
17  
70  
NA  
70  
13  
70  
NA  
56  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
3001 to 4000  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2 Pipe or 3-in.  
Concentric  
See notes at end of table.  
NOTE: Do not count elbows or pipe sections in terminations or within furnace. See shaded areas in Fig. 40, 41, 42, 43, and 44.  
EXAMPLE: An 042080 size furnace located in Indianapolis, elevation 650 ft above sea level, could be installed in an application requiring  
3 elbows and 17 ft of vent pipe, along with 5 elbows and 16 ft of combustion-air pipe. Table 7 indicates this application would allow a  
1-1/2-in. diameter vent pipe, but require a 2-in. diameter combustion air pipe (1-1/2-in. pipe is good for 20 ft with 3 elbows, but only 10  
ft with 5 elbows). Therefore, 2-in. diameter pipe must be used for both vent and combustion-air pipes since larger required diameter must  
always be used for both pipes. If same installation were in Albuquerque, elevation 5250 ft above sea level, installation would require 2-in.  
vent pipe and combustion-air pipe. At 5001- to 6000-ft elevation, 1-1/2-in. pipe is not allowed with 5 elbows, but 2-in. pipe is good for  
68 ft with 5 elbows.  
COMBUSTION-AIR AND VENT PIPE ATTACHMENT  
NOTE: All pipe joints must be watertight except attachment of combustion-air pipe to inlet housing connection, since it may be necessary to  
remove pipe for servicing.  
1. Attach combustion-air pipe to furnace as follows:  
a. Determine location of combustion-air intake pipe connection to combustion-air intake housing as shown in Fig. 36 for application.  
b. Reposition combustion-air intake housing plug fitting in appropriate unused intake housing connection.  
c. If required, insert perforated disk assembly (factory-supplied in loose parts bag) in intake housing where combustion-air intake pipe will  
be connected. If half disk set is required, install with shoulder of disk against stop in combustion-air inlet.  
d. Install pipe support (factory-supplied in loose parts bag) into selected furnace casing combustion-air pipe hole. Pipe support should be  
positioned at bottom of casing hole.  
e. Insert 2-in. diameter pipe into intake housing.  
f. Install casing hole filler cap (factory-supplied in loose parts bag) in unused combustion-air pipe casing hole.  
—34—  
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Table 7—Maximum Allowable Pipe Length (ft) (Continued)  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
4001 to 5000‡  
UNIT SIZE  
042040  
1
2
3
4
5
20  
70  
20  
70  
NA  
70  
16  
70  
6
15  
70  
15  
70  
NA  
68  
11  
70  
1-1/2  
2
1-1/2  
2
1-1/2  
2
2
40  
70  
40  
70  
23  
70  
36  
70  
35  
70  
35  
70  
18  
70  
31  
70  
30  
70  
30  
70  
13  
70  
26  
70  
25  
70  
25  
70  
8
70  
21  
70  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2-1/2  
2 Pipe or 3-in.  
Concentric  
3†  
56  
55  
54  
53  
52  
52  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
5001 to 6000‡  
UNIT SIZE  
042040  
1
2
3
4
5
17  
70  
17  
70  
NA  
68  
13  
70  
6
12  
70  
12  
70  
NA  
63  
8
1-1/2  
2
1-1/2  
2
1-1/2  
2
2
37  
70  
37  
70  
22  
70  
33  
70  
32  
70  
32  
70  
17  
70  
28  
70  
27  
70  
27  
70  
12  
70  
23  
70  
22  
70  
22  
70  
7
70  
18  
70  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2-1/2  
70  
2 Pipe or 3-in.  
Concentric  
3†  
53  
52  
50  
49  
48  
47  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
6001 to 7000‡  
UNIT SIZE  
042040  
1
2
3
4
5
15  
66  
15  
66  
NA  
62  
11  
66  
6
10  
64  
10  
64  
NA  
57  
6
1-1/2  
2
1-1/2  
2
1-1/2  
2
2
35  
70  
35  
70  
20  
70  
31  
70  
30  
70  
30  
70  
15  
70  
26  
70  
25  
68  
25  
68  
10  
68  
21  
68  
20  
67  
20  
67  
5
67  
16  
67  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2-1/2  
64  
2 Pipe or 3-in.  
Concentric  
3†  
49  
48  
47  
45  
44  
43  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
UNIT SIZE  
042040  
1
2
3
4
17  
62  
17  
62  
NA  
62  
14  
62  
5
12  
60  
12  
60  
NA  
57  
9
6
7
59  
7
59  
NA  
52  
NA  
59  
1-1/2  
2
1-1/2  
2
1-1/2  
2
2
32  
66  
32  
66  
18  
66  
29  
66  
27  
65  
27  
65  
13  
65  
24  
65  
22  
63  
22  
63  
8
63  
19  
63  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
7001 to 8000‡  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2-1/2  
60  
2 Pipe or 3-in.  
Concentric  
3†  
46  
44  
43  
41  
40  
38  
See notes at end of table.  
NOTE: A 2-in. diameter pipe must be used within the furnace casing. Make all pipe diameter transitions outside furnace casing.  
g. Drill a 1/8-in. hole in 2-in. combustion-air pipe using hole in intake housing as a guide.  
h. Install a field-supplied No. 6 or No. 8 sheet metal screw into combustion-air pipe.  
NOTE: DO NOT OVERTIGHTEN SCREW. Breakage to intake housing or fitting may cause air leakage to occur.  
NOTE: Do not attach combustion-air intake pipe permanently to combustion-air intake housing since it may be necessary to remove pipe for  
service of ignitor or flame sensor.  
Combustion-Air Intake Housing Plug Fitting: The combustion-air intake plug fitting must be installed in unused combustion-air intake housing.  
This fitting must be attached by using RTV sealant, or by drilling a 1/8-in. hole in fitting, using hole in intake housing as a guide. Install a  
field-supplied No. 6 or No. 8 sheet metal screw.  
NOTE: DO NOT OVERTIGHTEN SCREW. Breakage to intake housing or fitting may cause air leakage to occur.  
A plugged drain connection has been provided on this fitting for use when moisture is found in combustion-air intake pipe and combustion box.  
NOTE: Moisture in combustion-air intake may be result of improper termination. Ensure combustion-air intake pipe termination is similar to that  
shown in Fig. 39, 40, 41, 42, and 43 so it will not be susceptible to areas where light snow or other sources of moisture could be pulled in.  
—35—  
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Table 7—Maximum Allowable Pipe Length (ft) (Continued)  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
8001 to 9000‡  
UNIT SIZE  
042040  
1
2
3
4
15  
56  
15  
56  
NA  
56  
12  
56  
5
10  
55  
10  
55  
NA  
51  
7
6
5
53  
5
53  
NA  
46  
NA  
53  
1-1/2  
2
1-1/2  
2
1-1/2  
2
2
30  
62  
30  
62  
17  
62  
27  
62  
25  
60  
25  
60  
12  
60  
22  
60  
20  
58  
20  
58  
7
58  
17  
58  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
042080  
060080  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2-1/2  
55  
2 Pipe or 3-in.  
Concentric  
3†  
43  
41  
39  
37  
35  
34  
NUMBER OF 90° ELBOWS  
TERMINATION  
TYPE  
PIPE DIA  
(IN.)*  
ALTITUDE (FT)  
9001 to 10,000‡  
UNIT SIZE  
042040  
1
2
3
4
12  
51  
12  
51  
NA  
51  
9
5
7
49  
7
6
NA  
47  
NA  
47  
1-1/2  
2
1-1/2  
2
27  
57  
27  
57  
15  
57  
24  
57  
22  
55  
22  
55  
10  
55  
19  
55  
17  
53  
17  
53  
5
53  
14  
53  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
042060  
49  
NA  
46  
NA  
49  
1-1/2  
2
2
NA  
41  
NA  
47  
042080  
060080  
2 Pipe or 2-in  
Concentric  
2 Pipe or 2-in  
Concentric  
060100  
060120  
2-1/2  
51  
2 Pipe or 3-in.  
Concentric  
3
39  
37  
35  
33  
31  
29  
Disk usage-Unless otherwise specified, use perforated disk assembly (factory-supplied in loose parts bag)  
†Wide radius elbow.  
‡Vent sizing for Canadian installations over 4500 ft (1370 m) above sea level are subject to acceptance by the local authorities having jurisdiction.  
NA-Not Allowed; pressure switch will not make.  
NOTES:  
1. Do not use pipe size greater than those specified in table or incomplete combustion, flame disturbance, or flame sense lockout may occur.  
2. Size both the combustion-air and vent pipe independently, then use the larger of these two diameters for both pipes.  
3. Assume two 45° elbows equal one 90° elbow. Long radius elbows are desirable and may be required in some cases.  
4. Elbows and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.  
5. The minimum pipe length is 5 ft for all applications.  
If use of this drain connection is desired, drill out fitting’s tap plug with a 3/16-in. drill and connect a field-supplied 3/8-in. tube. This tube should  
be routed to open condensate drain for furnace and A/C (if used), and should be trapped. (See Fig. 38.)  
COMBUSTION AIR  
INTAKE HOUSING  
3/8" ID TUBE  
BURNER  
BOX  
3/16"  
DRILL  
COMBUSTION  
AIR PIPE  
4″  
(102mm)  
MIN  
TRAP  
TO OPEN  
DRAIN  
A93035  
Fig. 38—Intake Housing Plug Fitting Drain  
2. Attach vent pipe to furnace as follows:  
a. Determine location of vent pipe connection to inducer housing as shown in Fig. 36 for application.  
b. Reposition elastomeric (rubber) inducer housing outlet cap and clamp to appropriate unused inducer housing connection. Tighten clamp.  
WARNING: Inducer housing outlet cap must be installed and fully seated against inducer housing. Clamp must be  
tightened to prevent any condensate leakage. Failure to follow this warning could result in electrical shock, fire, personal  
injury, or death.  
c. Install pipe support (factory-supplied in loose parts bag) into selected furnace casing vent pipe hole. Pipe support should be positioned  
at bottom of casing hole.  
—36—  
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d. Be certain that mating surfaces of inducer housing connection, elastomeric coupling, and 2-in. diameter vent pipe are clean and dry.  
Assemble the elastomeric (rubber) vent coupling (with 2 loose clamps) onto inducer housing connection. Insert the 2-in. diameter vent  
pipe through the elastomeric (rubber) coupling and fully into inducer housing connection until it bottoms on the internal stop. Tighten  
both clamps to secure the pipe to inducer housing. Tighten the clamp screws to 15 in.-lb. of torque.  
e. Install casing hole filler plug (factory-supplied in loose parts bag) in unused combustion-air pipe casing hole.  
WARNING: Vent pipe must be installed and fully seated against inducer housing internal stop. Clamp must be  
tightened to prevent any condensate leakage. Failure to follow this warning could result in electrical shock, fire, personal  
injury, or death.  
NOTE: A 2-in. diameter pipe must be used within the furnace casing. Make all pipe diameter transitions outside furnace casing.  
ROOF  
18MAXIMUM  
BRACKET  
COUPLING  
COMBUSTION  
AIR  
VERTICAL SEPARATION  
VENT  
BETWEEN COMBUSTION  
AIR AND VENT  
3
3
8
6
/ FOR 3KIT  
4
4
/ FOR 2KIT  
MAINTAIN 12 IN. MINIMUM  
CLEARANCE ABOVE HIGHEST  
ANTICIPATED SNOW LEVEL.  
MAXIMUM OF 24 IN. ABOVE ROOF.  
A87224  
Fig. 39—Roof Termination (Preferred)  
3. Working from furnace to outside, cut pipe to required length(s).  
4. Deburr inside and outside of pipe.  
5. Chamfer outside edge of pipe for better distribution of primer and cement.  
6. Clean and dry all surfaces to be joined.  
7. Check dry fit of pipe and mark insertion depth on pipe.  
NOTE: It is recommended that all pipes be cut, prepared, and preassembled before permanently cementing any joint.  
8. After pipes have been cut and preassembled, apply generous layer of cement primer to pipe fitting socket and end of pipe to insertion mark.  
Quickly apply approved cement to end of pipe and fitting socket (over primer). Apply cement in a light, uniform coat on inside of socket  
to prevent buildup of excess cement. Apply second coat.  
9. While cement is still wet, twist pipe into socket with 1 /4 turn. Be sure pipe is fully inserted into fitting socket.  
10. Wipe excess cement from joint. A continuous bead of cement will be visible around perimeter of a properly made joint.  
11. Handle pipe joints carefully until cement sets.  
12. Support combustion-air and vent piping a minimum of every 5 ft (3 ft for SDR-21 or -26 PVC) using perforated metal hanging strap.  
13. Slope combustion-air and vent pipes toward furnace a minimum of 1/4 in. per linear ft with no sags between hangers.  
14. Use appropriate methods to seal openings where vent and combustion-air pipes pass through roof or side wall.  
C. Concentric Vent and Combustion-Air Termination Kit Installation  
NOTE: If these instructions differ from those packaged with termination kit, follow kit instructions.  
Combustion-air and vent pipes must terminate outside structure. A factory accessory termination kit must be installed in 1 of the installations  
shown in Fig. 39, 40, 41, 42, and 43. Four termination kits are available.  
1. The 2-in. termination bracket kit is for 1-in., 1-1/2 in., and 2-in. diameter 2-pipe termination systems.  
2. The 3-in. termination bracket kit is for 2-1/2 in., 3-in., and 4-in. diameter 2-pipe termination systems.  
3. The 2-in. concentric vent/air termination kit is for 1-in., 1-1/2 in., 2-in., and 2-1/2 in. diameter pipe systems when single penetration of wall  
or roof is desired.  
4. The 3-in. concentric vent/air termination kit is for 2-1/2 in., 3-in., and 4-in. diameter pipe systems when single penetration of wall or roof  
is desired.  
—37—  
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VENT  
COMBUSTION  
AIR  
MAINTAIN 12 IN. (305 mm).  
(18 IN. (457 mm) FOR CANADA)  
MINIMUM CLEARANCE  
ABOVE HIGHEST  
ANTICIPATED SNOW  
LEVEL. MAXIMUM OF  
24 IN. (610 mm) ABOVE ROOF.  
A93054  
Fig. 40—Concentric Vent and Combustion-Air RoofTermination (Preferred)  
OVERHANG OR ROOF  
12(305 mm) MINIMUM  
1MAXIMUM  
COMBUSTION-AIR  
VENT  
MAINTAIN 12 IN. (305 mm)  
CLEARANCE  
ABOVE HIGHEST  
ANTICIPATED SNOW  
LEVEL OR GRADE,  
WHICHEVER IS  
GREATER.  
A93055  
Fig. 41—Concentric Vent and Combustion-Air SideTermination  
OVERHANG OR ROOF  
12MINIMUM  
VENT  
90¡  
BRACKET  
12 IN. SEPARATION  
BETWEEN BOTTOM OF  
COMBUSTION AIR AND  
BOTTOM OF VENT  
MAINTAIN 12 IN.  
CLEARANCE  
ABOVE HIGHEST  
ANTICIPATED SNOW  
LEVEL OR GRADE,  
WHICHEVER IS  
GREATER.  
COMBUSTION-AIR  
A87225  
Fig. 42—Sidewall Termination of 12 in. or More  
—38—  
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OVERHANG OR ROOF  
12MINIMUM  
VENT  
90¡  
BRACKET  
COUPLING  
12 IN. SEPARATION  
BETWEEN BOTTOM OF  
COMBUSTION AIR AND  
BOTTOM OF VENT  
MAINTAIN 12 IN.  
CLEARANCE  
ABOVE HIGHEST  
ANTICIPATED SNOW  
LEVEL OR GRADE,  
WHICHEVER IS  
GREATER.  
COMBUSTION-AIR  
(ELBOW PARALLEL  
TO WALL)  
A87226  
Fig. 43—Sidewall Termination of Less than 12 in.  
NOTE: Shaded parts in Fig. 39, 40, 41, 42, and 43 are considered to be termination. These components should NOT be counted when determining  
pipe diameter. Roof termination is preferred since it is less susceptible to damage, has reduced chances to take in contaminants, and has less visible  
vent vapors. (See Fig. 39 or 40.) Sidewall termination may require sealing or shielding of building surfaces with a corrosive resistance material  
due to corrosive combustion products of vent system.  
EXTENDED EXPOSED SIDEWALL PIPES  
Sidewall combustion-air and vent pipe terminations may be extended beyond area shown in Fig. 42 or 43 in outside ambient by insulating pipes  
as indicated in Table 8.  
1. Determine combustion-air and vent pipe diameters, as stated above, using total pipe length and number of elbows.  
2. Using winter design temperature (used in load calculations), find appropriate temperature for your application and furnace model.  
3. Determine required insulation thickness for exposed pipe lengths.  
NOTE: Pipe length(ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed  
total allowable pipe length as specified in Table 7.  
TWO-PIPE TERMINATION KIT  
1. Determine location for termination.  
Consideration of the following should be made when determining an appropriate location for termination kit.  
a. Comply with all clearance requirements as stated in Table 5.  
b. Termination kit should be positioned where vent vapors will not damage plants/shrubs or air conditioning equipment.  
c. Termination kit should be positioned so that it will not be affected by wind eddy (such as inside building corners) or allow recirculation  
of flue gases, airborne leaves, or light snow.  
d. Termination kit should be positioned where it will not be damaged by or subjected to foreign objects, such as stones, balls, etc.  
e. Termination kit should be positioned where vent vapors are not objectionable.  
2. Cut 2 holes, 1 for each pipe, of appropriate size for pipe size being used.  
3. Loosely install elbow in bracket and place assembly on combustion-air pipe.  
Roof terminations-Loosely install pipe coupling on properly cut vent pipe. Coupling must be positioned so bracket will mount as shown  
in Fig. 39.  
For applications using combustion-air pipe option, indicated by dashed lines in Fig. 39, install 90° street elbow into 90° elbow, making  
U-fitting. A 180° U-fitting may be used.  
Sidewall terminations-Install bracket as shown in Fig. 42 or 43.  
For applications using vent pipe option indicated by dashed lines in Fig. 42, rotate vent elbow 90° from position shown in Fig. 42.  
4. Disassemble loose pipe fittings. Clean and cement using same procedures as used for system piping.  
5. Check required dimensions as shown in Fig. 39, 42, or 43.  
CONCENTRIC VENT/AIR TERMINATION KIT  
1. Determine location for termination.  
Consideration of the following should be made when determining an appropriate location for termination kit.  
a. Comply with all clearance requirements as stated in Table 5.  
—39—  
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Table 8—Maximum Allowable Exposed Vent Pipe Length (ft) With and Without Insulationin Winter Design Temperature  
Ambient*  
INSTALLATION THICKNESS  
WINTER DESIGN  
TEMPERATURE  
(°F)  
MAXIMUM PIPE  
DIAMETER  
(IN.)  
(IN.)  
UNIT  
SIZE  
1/2 or THICKER  
INSTALLATION†  
0
3/8  
20  
0
-20  
20  
0
-20  
20  
0
-20  
20  
0
-20  
20  
0
-20  
20  
0
-20  
20  
0
-20  
20  
0
2
2
2
30  
12  
2
34  
17  
8
44  
21  
9
50  
27  
16  
57  
30  
16  
64  
37  
23  
70  
38  
21  
70  
38  
23  
70  
38  
19  
70  
53  
36  
50  
50  
46  
70  
70  
57  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
64  
45  
50  
50  
50  
70  
70  
69  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
70  
042040  
042060  
1-1/2  
1-1/2  
1-1/2  
2
2
2
1-1/2  
1-1/2  
1-1/2  
2
2
2
1-1/2  
1-1/2  
1-1/2  
2-1/2  
2-1/2  
2-1/2  
2
2
2
3
3
042080  
060080  
060100  
060120  
-20  
20  
0
-20  
3
* Pipe length (ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable pipe length as  
specified in Table 8.  
† Insulation thickness based on R value of 3.5 (ft_ • °F• hr)/(Btu•in.)  
b. Termination kit should be positioned where vent vapors will not damage plants/shrubs or air conditioning equipment.  
c. Termination kit should be positioned so it will not be affected by wind eddy (such as inside building comers) or that may allow  
recirculation of flue gases, airborne leaves, or light snow.  
d. Termination kit should be positioned where it will not be damaged by or subjected to foreign objects, such as stones, balls, etc.  
e. Termination kit should be positioned where vent vapors are not objectionable.  
2. Cut one 4-in. diameter hole for 2-in. kit, or one 5-in. diameter hole for 3-in. kit.  
3. Loosely assemble concentric vent/air termination components together using instructions in kit.  
4. Slide assembled kit with rain shield REMOVED through hole.  
Roof terminations-Locate assembly through roof to appropriate height as shown in Fig. 40.  
Sidewall terminations-Locate assembly through sidewall with rain shield positioned no more than 1-in. from wall as shown in Fig. 41.  
NOTE: Do not allow insulation or other materials to accumulate inside of pipe assembly when installing it through hole.  
5. Disassemble loose pipe fittings. Clean and cement using same procedures as used for system piping.  
6. Check required dimensions as shown in Fig. 40 or 41.  
D. Multiventing and Vent Terminations  
When 2 or more 355MAV furnaces are vented near each other, each furnace must be individually vented. NEVER common vent or breach vent  
355MAV furnaces. When 2 or more 355MAV furnaces are vented near each other, 2 vent terminations may be installed as shown in Fig. 44, 45,  
46, 47, or 48, but the next vent termination must be at least 36 in. away from first 2 terminations. It is important that vent terminations be made  
as shown to avoid recirculation of flue gases. Dimension A in Fig. 44, 45, 46, 47, and 48 represents distance between pipes or rain shields, as  
touching or 2-in. maximum separation.  
PROCEDURE 10—CONDENSATE DRAIN  
A. General  
Condensate trap is shipped installed in the blower shelf and factory connected for UPFLOW applies Condensate trap must be RELOCATED for  
use in DOWNFLOW and HORIZONTAL applications.  
Condensate trap MUST be used for all applications.  
—40—  
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An external trap is not required when connecting the field drain to this condensate trap.  
The field drain connection (condensate trap or drain tube coupling) is sized for l/2-in. CPVC, 1/2-in. PVC, or 5/8-in. ID tube connection.  
Drain pipe and fittings must conform to ANSI standards and ASTM D1785, D2466 or D2846. CPVC or PVC cement must conform to ASTM  
D2564 or F493. Primer must conform to ASTM F656. In Canada, use CSA or ULC certified schedule 40 CPVC or PVC drain pipe, fittings, and  
cement.  
When a condensate pump is required, select a pump which is approved for condensing furnace applications. To avoid condensate spillage, select  
a pump with an overflow switch.  
Furnace condensate is mildly acidic, typically in the pH range of 3.2 to 4.5. Due to corrosive nature of this condensate, a condensate pH neutralizing  
filter may be desired. Check with local authorities to determine if a pH neutralizer is required.  
A
A96128  
Fig. 44—Rooftop Termination (Dimension “A” is Touching or 2–in. Maximum Separation)  
VENT  
VENT  
A
COMBUSTION  
AIR  
A93056  
Fig. 45—Concentric Vent and Combustion-Air Roof Termination  
(Dimension “A” is Touching or 2-in. Maximum Separation)  
B. Application  
The furnace, A/C, and humidifier drains may be combined and drained together. The A/C drain must have an external, field-supplied trap prior  
to the furnace drain connection. All drain connections (furnace, A/C, or humidifier) must be terminated into an open or vented drain as close to  
the respective equipment as possible to prevent siphoning of the equipment’s drain.  
See Fig. 49 for example of possible field drain attachment using 1/2-in. CPVC or PVC tee for vent and A/C or humidifier drain connection.  
CAUTION: Unit must be installed, operated, and then turned and left off in an unoccupied structure during cold  
weather when temperature drops to 32°F or below unless drain trap and drain line have adequate freeze protection. See  
Service and Maintenance Instructions for winterizing procedure. (See Fig. 15.)  
Outdoor draining of the furnace is permissible if allowed by local codes. Caution should be taken when freezing ambient may freeze drain pipe  
and prohibit draining.  
WARNING: Caution should be taken to prevent draining where slippery conditions may cause personal injuries.  
Excessive condensate draining may cause saturated soil conditions which may result in damage to plants.  
C. Condensation Drain Protection  
Freezing condensate left in condensate trap and drain line may cause cracks, and possible water damage may occur. If freeze protection is required,  
use condensate freeze protection accessory or equivalent 3 to 6 watt per ft at 120-v and 40°F self-regulating, shielded, and waterproof heat tape.  
See Installation Instructions supplied with accessory or heat tape manufacturer’s recommendations.  
—41—  
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1(25 mm) MAXIMUM  
(TYP)  
COMBUSTION AIR  
VENT  
A
VENT  
A93057  
A96129  
A96130  
Fig. 46—Concentric Vent and Combustion-Air Side Termination  
(Dimension “A” is Touching or 2-in. Maximum Separation)  
VENT  
COMBUSTION AIR  
COMBUSTION AIR  
A
Fig. 47—Sidewall Termination of 12 in. or Less  
(Dimension “A” is Touching or 2-in. Maximum Separation)  
VENT  
COMBUSTION AIR  
COMBUSTION AIR  
A
Fig. 48—Sidewall Termination of More than 12 in.  
(Dimension “A” is Touching or 2-in Maximum Separation)  
—42—  
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OPEN STAND  
PIPE FOR  
A/C OR  
HUMIDIFIER  
DRAIN  
TEE  
TO OPEN  
DRAIN  
A94054  
Fig. 49—Example of Field Drain Attachment  
1. Fold heat tape in half and wrap on itself 3 times.  
2. Locate heat tape between sides of condensate trap back. (See Fig. 50.)  
3. Use wire ties to secure heat tape in place. Wire ties can be positioned in notches of condensate trap sides. (See Fig. 50.)  
4. Wrap field drain pipe with remaining heat tape, approximately 1 wrap per ft.  
5. When using field-supplied heat tape, follow heat tape manufacture’s instructions for all other installation guidelines.  
CONDENSATE TRAP  
WIRE TIE(S)  
HEAT TAPE  
(3 WRAPS MINIMUM)  
A93036  
Fig. 50—Condensate Trap Heat Tape  
SEQUENCE OF OPERATION  
CAUTION: Furnace control must be grounded for proper operation, or control will lock out. Control is grounded  
through green wire routed to gas valve and burner box screw.  
Using schematic diagram (see Fig. 30.), follow sequence of operation through different modes. This furnace has a new control system. Read and  
follow wiring diagra, carefully.  
NOTE: If 115-v power supply to furnace or blower access panel switch is interrupted during a call for heat, blower operates at low-heat speed  
for 60 sec when power is restored before heating cycle is resumed.  
—43—  
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PROCEDURE 1—SELF-TEST MODE  
The control center goes through a brief self-test whenever 115-v or 24-v power is interrupted. The self-test takes approximately 2 sec to complete.  
After power is restored, red (microprocessor) LED briefly comes on. Then green LED comes on for 1 sec, followed by 1 sec where both yellow  
and green LEDs are on. During this time, the microprocessor is checking itself.  
PROCEDURE 2—HEATING MODE  
When thermostat calls for heat, R-W/W1 circuit closes.  
1. Prepurge period—The inducer motor is turned on and slowly comes up to speed. When low-pressure switch closes, inducer motor RPM  
is noted by microprocessor, and a 25 sec prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is  
then used to determine required RPM necessary to operate inducer in low-heat mode.  
NOTE: The heat cycle can start in either high or low heat. If a high-heat cycle is initiated, the inducer continues increasing its speed after  
low-pressure switch closes. When high-pressure switch closes, inducer motor RPM is noted by microprocessor before the 25 sec prepurge period  
begins. The RPM is used to evaluate vent system resistance. This evaluation is then used to determine required RPM necessary to operate inducer  
in high-heat mode.  
2. Humidifier (HUM)—The HUM terminal is energized after the inducer prepurge period is completed.  
3. Ignitor warm up—At end of prepurge period, the hot surface ignitor (HSI) is energized for a 17-sec HSI warm-up period.  
4. Ignition sequence—After HSI ignitor warm-up period is completed, the gas valve opens, permitting gas flow to burners where it is ignited.  
After 5 sec, the HSI is de-energized, and a 2-sec flame-sensing period begins.  
NOTE: The initial heat mode after 115-v or 24-v power interruption will be LOW HEAT. Low heat remains energized for 16 minutes before high  
heat is initiated, providing thermostat is still calling for heat.  
After initial cycle, the microprocessor evaluates the length of low- and high-heat operating times and calculates optimum length of low and high  
heat for next heat cycle. This accommodates the heat load requirement seen as a result of thermostat operating time.  
5. Flame sensing—When burner flame is sensed, the control center holds gas valve open and begins blower on delay period.  
NOTE: Ignition sequence repeats 3 additional times before a lockout occurs. Lockout automatically resets after 3 hr, or can be manually reset  
by turning 115-v or 24-v power off (not at thermostat) for 3 sec minimum, then turning on again.  
6. Inducer speed operation—If cycle starts in low heat, inducer speed reduces slightly after flame sense. If cycle starts in high heat, inducer  
speed increases 15 sec after flame sense. The reduction in speed in low heat is to optimize combustion for maximum efficiency.  
7. Blower on delay—The blower starts 60 sec after flame sense if cycle started in low heat or 35 sec after flame sense if cycle started in high  
heat.  
NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor is turned off for 1/10 of a sec where a coast down calibration  
is done to evaluate resistance of the conditioned air duct system. The microprocessor then determines blower RPM required to provide proper  
airflow for heating mode.  
8. Electronic Air Cleaner—The EAC-1 terminal is energized whenever the blower operates.  
9. Blower off delay—When thermostat is satisfied, the R-W/W1 signal is terminated, de-energizing gas valve (stopping gas flow to burners),  
and HUM terminal is de-energized.  
The blower reduces its speed to low-heat RPM. The blower and EAC remain operating 90, 135, 180, or 225 sec (depending on blower off  
time selection). The furnace is factory set for a 90-sec blower off delay.  
10. Post purge—The inducer continues operating for 15 sec after gas valve is de-energized.  
PROCEDURE 3—HEATING MODE-TWO STAGE  
The control center provides 2-stage heating using a single-stage thermostat. The control center maximizes comfort while optimizing efficiency to  
meet the demands of conditioned area when a thermostat R-W/W1 signal is received.  
If thermostat control over furnace staging is desired, a 2-stage thermostat can be used. When control center receives a thermostat R-W/W1 and  
R-W2 signal, high heat is energized and when a R-W/W1 signal alone is received, low heat is energized. This method overrides microprocessor  
control of high or low heat.  
NOTE: When using 2-stage thermostat operation with R-W/W1 and R-W2 signals, setup switch SW-2 MUST be in ON position.  
The heat cycle operates as stated in Heating Mode section.  
To allow for greater comfort, 2-stage thermostat control is recommended when zone systems are used.  
PROCEDURE 4—EMERGENCY HEAT MODE  
NOTE: The furnace should not be operated in emergency heat mode for extended periods of time. Operation is only recommended to provide  
heat until replacement components can be obtained or fault resolved.  
In this mode, the microprocessor is bypassed and motors operate at full speed with high-heat operation. The heat exchangers, motors, and  
electronics can be overstressed and may reduce the life of components if operated for an extended period.  
NOTE: No safeties are bypassed when using emergency heat mode.  
Emergency heat mode can be selected using setup switch SW-4. SW-4 should be used when a fault condition exists or difficult to resolve problems  
occur. This allows heating until fault can be corrected.  
In emergency heat mode, the normal heat mode outlined in Heating Mode section is not followed. The following sequence will occur:  
When thermostat calls for heat, the R-W/W-1 circuits close.  
1. Prepurge period—The inducer motor is turned on IMMEDIATELY operating at maximum speed, closing low- and high-pressure switches.  
Prepurge begins 25 sec after high-pressure switch closes.  
—44—  
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2. Blower on—The blower motor is turned on IMMEDIATELY and slowly increases to maximum speed as soon as a call for heat is received.  
No blower calibration occurs.  
3. Electronic Air Cleaner—The EAC-1 terminal does not operate in emergency heat mode.  
4. Humidifier—The HUM terminal is energized IMMEDIATELY.  
5. Ignitor warm up—The HSI is energized for a 17 sec warm-up period after prepurge period is completed.  
6. Ignition sequence—After HSI warm-up period has completed, the gas valve is energized, permitting gas flow to burners where it is ignited.  
After 5 sec, the HSI is de-energized, and a 2-sec flame-sensing period begins.  
NOTE: Emergency heat mode only operates in high heat.  
7. Flame sensing—When burner flame is sensed, control center holds gas valve open. If burner flame is not sensed, control center de-energizes  
gas valve and ignition sequence is repeated.  
NOTE: Ignition sequence repeats 3 additional times before lockout occurs. Lockout automatically resets after 3 hr, or can be manually reset by  
turning 115-v or 24-v power off (not at thermostat) for 3 sec minimum, then turning on again. Fault codes will not flash in emergency heat mode.  
8. Blower off delay—When thermostat is satisfied, the R-W/W1 signal is terminated, de-energizing gas valve (stopping gas flow to burners),  
and HUM terminal is de-energized. The blower stops immediately.  
9. Post purge—Post purge does NOT occur. The inducer stops immediately.  
PROCEDURE 5—COOLING MODE  
A. Single-Speed Applications  
When thermostat calls for cooling, the R-G and R-Y/Y2 circuits close.  
1. Cooling unit—The cooling unit starts when thermostat R-Y signal is received.  
2. Blower on—The control center starts blower immediately when it receives an R-Y/Y2 and R-G signal. The blower starts at approximately  
400-500 RPM. After 20 sec, the blower is turned off for 1/10 of a sec where a coast down calibration is done to evaluate resistance of the  
conditioned air duct system. The microprocessor then determines blower RPM required to provide selected cooling airflow.  
NOTE: In cooling mode, the microprocessor adjusts blower RPM to operate at 400 CFM per ton as selected on A/C setup switches. Airflow will  
be reduced to 315 CFM per ton when a dehumidification demand exists. See Air Conditioning Setup Switches section. There is also a chart on  
wiring diagram. (See Fig. 30.)  
NOTE: If Y/Y2 thermostat lead is not connected to furnace control center, blower motor operates in continuous fan speed and indoor coil  
freeze-up may occur.  
3. Electronic Air Cleaner—The EAC-1 terminal is energized whenever blower operates.  
4. Cooling unit—The cooling unit stops when thermostat R-Y signal is terminated.  
5. Blower off delay—When thermostat is satisfied, the R-Y/Y2 and R-G signals are terminated, and blower remains operating for 90 sec. The  
blower airflow will drop by 21 percent during the off-delay period when the DE jumper is connected. The DE jumper is only removed to  
enable the DEHUM input for use with a thermidistat or humidistat for dehumidification purposes.  
B. Two-Speed Applications  
For details on 2-speed cooling applications, refer to Fig. 51.  
PROCEDURE 6—HEAT PUMP MODE  
A. Single-Speed Applications  
When furnace is operating in heat pump heating mode, R-Y/Y2 and R-G circuits are closed energizing heat pump, and blower operates at cooling  
speed. When heat pump defrost is required, R-W/W1 circuits close starting gas heat cycle, and blower adjusts to low-heat speed.  
1. Prepurge period—The inducer motor is turned on and slowly comes up to speed. When low-pressure switch closes, inducer motor RPM  
is noted by microprocessor, and a 25 sec prepurge period begins. The RPM is used to evaluate vent system resistance. This evaluation is  
then used to determine required RPM necessary to operate inducer in low-heat mode.  
NOTE: The heat cycle can start in either high or low heat. If a high-heat cycle is initiated, inducer continues increasing its speed after low-pressure  
switch closes. When high-pressure switch closes, inducer motor RPM is noted by microprocessor before the 25 sec prepurge period begins. The  
RPM is used to evaluate vent system resistance. This evaluation is used to determine required RPM necessary to operate inducer in high-heat mode.  
2. Humidifier—The HUM terminal is energized after inducer prepurge period is completed.  
3. Ignitor warm up—After prepurge period, HSI is energized for 17 sec.  
4. Ignition sequence—After HSI warm-up period is completed, the gas valve is energized, permitting gas flow to the burners where it is  
ignited. After 5 sec, the HSI is de-energized, and a 2-sec flame-sensing period begins.  
5. Flame sensing—When burner flame is sensed, control center holds gas valve open.  
If burner flame is not sensed, control center de-energizes gas valve, and ignition sequence is repeated.  
6. Blower off period—Ten sec after gas valve is energized, the blower stops for 25 sec to allow heat exchangers to warm up.  
7. Blower on delay—After blower off period, blower starts.  
NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor is turned off for 1/10 of a sec where a coast down calibration  
is done to evaluate resistance of the conditioned air duct system. The microprocessor then determines blower RPM required to provide proper  
airflow for heating mode.  
—45—  
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VARIABLE-SPEED  
CONDENSING  
FURNACE  
THERMIDISTAT™  
CONTROL  
2-SPEED  
AIR CONDITIONER  
HEAT STAGE 2 O/W2  
COOL STAGE 1 Y1/W2  
W2  
Y1  
Y2  
R
W/W1  
W/W1  
Y/Y2  
HEAT STAGE 1  
COOL STAGE 2  
FAN  
Y/Y2  
G
G
R
24 VAC HOT  
R
DEHUM  
DE  
DEHUMIDIFY DHUM  
COM  
HUM  
C
C
24 VAC COMM  
HUMIDIFIER  
SOLENOID VALVE  
(24 VAC)  
HUM  
HUMIDIFY  
N/A  
B
OUTDOOR  
SENSOR  
S1  
S2  
OUTDOOR  
SENSOR  
CONNECTION  
A01473  
Fig. 51—Wiring Schematic for 2-Speed Application with Thermidistat Control  
8. Electronic Air Cleaner—The EAC-1 terminal is energized whenever blower operates.  
9. Inducer speed operation—If cycle starts in low heat, inducer speed reduces slightly after the flame sense. If cycle starts in high heat,  
inducer speed increases 15 sec after flame sense. The reduction in speed in low heat is to optimize combustion for maximum efficiency.  
10. Call for heat terminated—When the call for heat is satisfied, the R-W/W1 signal is terminated, de-energizing gas valve (stopping gas flow  
to burners), and HUM terminal is de-energized.  
a. R-W/W1 signal terminated with R-Y/Y2 and R-G still present—The blower changes its speed to cooling RPM.  
b. R-W/W1 with R-Y/Y2 and R-G signals terminated—The blower continues to operate completing a normal heating blower off delay.  
11. Post purge—The inducer continues operating for 15 sec after gas valve is de-energized.  
B. Two-Speed Applications  
For details on 2-speed heat pump applications, refer to Fig. 52.  
PROCEDURE 7—CONTINUOUS FAN MODE  
1. Operating with continuous fan only  
a. Call for continuous fan—The thermostat closes R-G circuit.  
b. Blower on—The blower starts immediately.  
NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor is turned off for 1/10 of a sec where a coast down calibration  
is done to evaluate resistance of the conditioned air duct system. The microprocessor then determines blower RPM required to provide proper  
airflow for heating mode.  
NOTE: The continuous fan speed is the same as low-heat speed unless it is field adjusted to another desired airflow. See Continuous Fan Setup  
Switches section. There is also a chart on wiring diagram. (See Fig. 30.)  
c. Electronic Air Cleaner—The EAC-1 terminal is energized whenever blower operates, regardless of operating mode.  
2. Operating with continuous fan (R-G) and call for heat (R-W/W1) is received—Same as heat pump mode except blower on delay is 10  
sec less than heat mode. After call for heat (R-W/W1) is terminated, the blower remains operating at low-heat speed for selected blower  
off delay before resuming continuous fan speed.  
3. Operating with continuous fan (R-G) and call for cooling (R-Y/Y2) is received— See Cooling Mode section. After call for cooling  
(R-Y/Y2) is terminated, the blower remains operating at cooling speed for 90 sec before resuming continuous fan speed.  
PROCEDURE 8—COMPONENT TEST  
All components are functionally operated except gas valve with component test feature.  
This feature helps diagnose a system problem in case of a component failure.  
NOTE: Setup switch SW-1 MUST be in OFF position or Fault Code 22 (setup error) will occur.  
NOTE: NO thermostat signal may be present at control center, and all blower time delay off periods must be completed.  
To initiate component test feature, proceed with the following:  
—46—  
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VARIABLE-SPEED  
CONDENSING  
FURNACE  
THERMIDISTAT™  
CONTROL  
2-SPEED  
HEAT PUMP  
W2  
RVS COOLING O/W2  
HEAT/COOL  
O
STAGE 1  
Y1/W2  
Y1  
(COMPRESSOR LO)  
HEAT STAGE 3  
(FURNACE)  
W2  
W/W1  
W/W1  
Y/Y2  
HEAT/COOL  
Y/Y2  
G
Y2  
STAGE 2  
(COMPRESSOR HI)  
G
R
FAN  
W3  
R
24 VAC HOT  
R
DEHUM  
DE  
DEHUMIDIFY DHUM  
COM  
HUM  
C
C
24 VAC COMM  
HUMIDIFIER  
SOLENOID VALVE  
(24 VAC)  
HUM  
HUMIDIFY  
N/A  
B
OUTDOOR  
SENSOR  
S1  
S2  
OUTDOOR  
SENSOR  
CONNECTION  
A01474  
Fig. 52—Wiring Schematic for 2-Speed Heat Pump Application with Thermidistat Control (Dual Fuel)  
1. Leave 115-v power to furnace turned on.  
2. Remove main furnace door.  
3. Remove blower access panel.  
4. Move setup switch SW-6 to ON position.  
5. Manually close blower access panel door switch. Use a piece of tape to hold switch closed.  
WARNING: Blower access panel door switch opens 115-v power to control center. No component operation can  
occur. Caution must be taken when manually closing this switch for service purposes. Failure to follow this warning could  
result in personal injury or death.  
When items 1-5 have been completed, the following will occur:  
1. The control center goes through a brief self-test. This self-test takes approximately 2 sec to complete. After door switch is closed, red  
(microprocessor) LED briefly comes on. Then green LED comes on for 1 sec, followed by 1 sec where both green and yellow LEDs are  
on. During this time, the microprocessor is checking itself.  
2. Inducer motor operates for 20 sec at low speed, operates for 20 sec at high speed, then turns off. Hot surface ignitor is energized for 15  
sec, then de-energized.  
3. Main blower motor operates for 20 sec at low speed, operates for 20 sec at high speed, then turns off.  
4. After component operation test is completed, 1 or more fault codes (11, 22, 41, or 42) will flash. See service label on back of main furnace  
door for explanation of fault codes.  
NOTE: To repeat component test, turn setup switch SW-6 to OFF and then back to ON.  
After component test, perform the following:  
1. Release blower panel access door switch and turn setup switch SW-6 to OFF position.  
2. If applicable, replace blower access panel and check LED status by removing plug in blower access panel.  
3. Reinstall main furnace door if all LEDs are off, indicating furnace is ready to operate when a signal from thermostat is received.  
PROCEDURE 9—BYPASS HUMIDIFIER MODE  
When setup switch SW-3 BPH is in ON position, RPM calculated for low heat is multiplied by 1.15 for all furnace model sizes. This compensates  
for increased return-air temperature caused by bypassed air supply.  
PROCEDURE 10—DEHUMIDIFICATION MODE  
A dehumidification input is provided via a 1/4 in. male quick-connect terminal labeled DEHUM located next to the transformer secondary  
connections. When there is a dehumidify demand, the DEHUM input is activated, which means 24 vac signal is removed from the DEHUM input  
terminal. In other words, the DEHUM input logic is reversed. the DEHUM input is turned ON when no dehumidify demand exists and is turned  
OFF when demand exists. This logic reversal has come about from historical use of a standard humidistat to do dehumidification since the contacts  
open on high humidity, thus removing the 24-v signal to initiate dehumidification.  
—47—  
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Table 10—Blower Off Delay Setup Switch (SW) Position  
DESIRED HEATING  
SETUP SWITCH  
MODE BLOWER-OFF  
DELAY (SEC)  
SW-3  
SW-4  
90  
OFF  
OFF  
ON  
OFF  
ON  
OFF  
ON  
135  
180  
225  
ON  
The DEHUM output on the thermidistat control or the humidistat output, is connected directly to the DEHUM terminal on the furnace control.  
In addition, the DE jumper located next to the DEHUM terminal must be removed to enable the DEHUM input (See Fig. 33 and 34). When a  
dehumidify demand exists, the furnace control reduces the blower airflow by 21 percent to 315 CFM per ton during continuous fan or cooling  
operation.  
This blower speed reduction compensates for high humidity conditions during cooling operation on all furnace model sizes. Reference Thermidistat  
Control Installation, Start-Up, and Operating Instructions for further details.  
PROCEDURE 11—ZONE MODE  
When setup switch SW-5 MZ is in ON position, blower motor control is the same as above except with the following exceptions:  
1. While blower is operating in either low heat or continuous fan, the coast down calibration is performed once a minute to update blower RPM  
for zone damper position changes during a given cycle unless the blower pulse width to blower motor is greater than 60 percent. This  
prevents nuisance faults from occurring when a high continuous fan CFM has been selected.  
2. While blower is operating in either high heat or cooling, blower pulse width to blower motor is frozen when blower RPM is within 10  
percent of calculated blower RPM for 5 sec.  
START-UP PROCEDURES  
PROCEDURE 1—GENERAL  
1. The furnace must have a 115-v power supply properly connected and grounded.  
NOTE: Proper polarity must be maintained for 115-v wiring. If polarity is incorrect, control status indicator light will flash rapidly and the furnace  
will not operate.  
2. Thermostat wire connections at terminals R, W/W1, G, and Y/Y2 must be made at 24-v terminal block on control center.  
3. Natural gas service pressure must not exceed 0.5 psig (14-in. wc), but must be no less than 0.16 psig (4.5-in. wc).  
4. Blower access panel must be in place to complete 24-v electrical circuit to furnace.  
CAUTION: These furnaces are equipped with a manual reset limit switch in burner box. This switch opens if an  
overheat condition (rollout) occurs in burner enclosure. Correct inadequate combustion-air supply or improper venting  
condition and reset switch. DO NOT jumper this switch.  
Before operating furnace, check each manual reset switch for continuity. If necessary, press button to reset switch.  
PROCEDURE 2—SELECT SETUP SWITCH POSITIONS  
A. Air Conditioning (A/C) Setup Switches  
The air conditioning setup switches are used to match furnace airflow to cooling unit used. This furnace will provide 400 CFM per selected air  
conditioning tonnage.  
To set the desired cooling airflow:  
1. Remove main furnace door and blower access panel.  
2. Locate A/C setup switches on control center. (See Fig. 31.)  
3. Determine air conditioning tonnage used.  
4. Use Table 9 or wiring schematic to determine proper setup position of A/C switches. (See Fig. 30 and 53.)  
NOTE: Excessive airflow caused by improper A/C switch setup may cause condensate blow off in cooling mode.  
5. Replace main furnace door and blower access panel.  
NOTE: EAC-1 terminal is energized whenever blower operates. HUM terminal is only energized when gas valve is energized.  
B. Continuous Fan (CF) Setup Switches  
The CF setup switches are used to select desired airflow when thermostat is in continuous fan mode. This setup feature allows continuous fan  
airflow to be adjusted. To set desired continuous fan airflow:  
1. Remove main furnace door and blower access panel.  
2. Locate CF setup switches on control center. (See Fig. 31.)  
3. Determine desired continuous fan airflow.  
4. Use Table 10 or wiring schematic to determine proper setup position of CF switches. (See Fig. 30 and 54.)  
—48—  
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Table 9—Air Conditioning (A/C) Airflow Switch Position  
A/C SETUP  
AIR  
ALLOWABLE FURNACE MODEL SETUP  
SWITCH POSITION  
CONDITIONER CFM AIRFLOW  
(TONS)  
A/C-1  
A/C-2  
A/C-3  
042040  
3 Tons  
042060  
3 Tons  
042080  
3 Tons  
060080  
5 Tons  
060100  
5 Tons  
060120  
5 Tons  
1200 or  
2000  
Default  
OFF  
OFF  
OFF  
1200 CFM 2000 CFM 1200 CFM 2000 CFM 2000 CFM 2000 CFM  
1–1/2  
2
2–1/2  
3
3–1/2  
4
5
600  
800  
ON  
OFF  
ON  
OFF  
ON  
OFF  
ON  
ON  
OFF  
OFF  
ON  
OFF  
OFF  
OFF  
ON  
ON  
ON  
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1000  
1200  
1400  
1600  
2000  
OFF  
ON  
ON  
ON  
X–Indicates allowable selection.  
1
OFF  
A95198  
Fig. 53—Example of Setup Switch in OFF Position  
A99118  
Fig. 54—Inducer Housing Drain Tube  
NOTE: The CF switches are factory set to provide continuous fan airflow equal to low-heat mode.  
5. Replace main furnace door and blower access panel.  
C. Setup Switches (SW)  
The control center has 8 setup switches that may be set to meet the application requirements. Position these setup switches for the appropriate  
requirement.  
1. Remove main furnace door and blower access panel.  
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2. Locate setup switches on control center. (See Fig. 31.)  
3. See Table 11 for setup switch description. (See Fig. 30.)  
4. Replace main furnace door and blower access panel.  
Table 11—Setup Switch Description  
SETUP  
SWITCH NO.  
NORMAL  
POSITION  
DESCRIPTION  
OF USE  
SW-1  
(FLT)  
Turn switch to ON for fault history display. No thermostat signal  
can be present for fault history display.  
OFF  
Turn switch to ON to lock furnace in low-heat mode only or  
when using a 2-stage thermostat with a R-W/W1 and R-W2 sig-  
nals.  
Turn switch to ON when a bypass humidifier is used. This com-  
pensates for higher return-air temperature and provides 15 per-  
cent more airflow in low-heat mode only.  
Turn switch to ON to bypass microprocessor control. Furnace  
will operate at high heat only with main blower and inducer mo-  
tor operating at maximum RPM. NO safeties are bypassed.  
Turn switch to ON when modulating dampers are used. In this  
mode, main blower speed is recalculated once every minute  
while furnace is in low-heat or continuous fan mode.  
SW-2  
OFF  
OFF  
OFF  
OFF  
(LOW)  
SW-3  
(BPH)  
SW-4  
(EMER HEAT)  
SW-5  
(MZ)  
Turn switch to ON to initiate component test. Furnace will oper-  
ate inducer motor for 20 sec at low speed, operate inducer motor  
for 20 sec at high speed, energize HSI for 15 sec, operate blower  
for 20 sec at low speed, and operate blower for 20 sec at high  
speed. SW-1 must be in OFF position. No thermostat signal can  
be present for component test to be initiated.  
SW-6  
(COMP TEST)  
OFF  
SW-7 and SW-8  
(Blower Off Delay)  
Adjust switches to provide desired heating mode blower off de-  
lay time. 90, 135, 180, or 225 sec.  
See Table 12  
Table 12—Blower Off Delay Setup Switch Position  
SETUP SWITCH (SW-7 AND SW-8) POSITION  
DESIRED HEATING  
MODE BLOWER  
OFF DELAY (SEC)  
SW-7  
SW-8  
90  
OFF  
ON  
OFF  
ON  
OFF  
OFF  
ON  
135  
180  
225  
ON  
NOTE: If a bypass humidifier is used, setup switch SW-3 (BPH) should be in ON position. This prevents nuisance limit trips caused by the  
increased temperature in return air resulting from bypass.  
NOTE: If modulating dampers are used, setup switch SW-5 (MZ) should be in ON position. This allows furnace control center to compensate  
for modulating dampers. The control re-calibrates for new system static conditions once every minute while operating in low-heat or continuous  
fan modes.  
PROCEDURE 3—PRIME CONDENSATE TRAP WITH WATER  
CAUTION: Condensate trap must be PRIMED or proper draining may not occur. The condensate trap has 2 internal  
chambers which can ONLY be primed by pouring water into the inducer drain side of condensate trap.  
1. Remove upper inducer housing drain connection cap. (See Fig. 54.)  
2. Connect field-supplied 1/2-in. ID tube to upper inducer housing drain connection.  
3. Insert field-supplied funnel into tube.  
4. Pour 1 quart of water into funnel/tube. Water should run through inducer housing, overfill condensate trap, and flow into open field drain.  
(See Fig. 55.)  
5. Remove funnel and tube from inducer housing and replace drain connection cap and clamp.  
PROCEDURE 4—PURGE GAS LINES  
If not previously done, purge the lines after all connections have been made and check for leaks.  
WARNING: Never purge a gas line into a combustion chamber. Never use matches, candles, flame, or other sources  
of ignition for the purpose of checking leakage. Use a soap-and-water solution to check for leakage. Failure to follow this  
warning could result in fire, explosion, personal injury, or death.  
PROCEDURE 5—ADJUSTMENTS  
A. Set Gas Input Rate  
Furnace gas input rate on rating plate is for installations at altitudes up to 2000 ft.  
In the U.S.A., the input rating for altitudes above 2000 ft must be reduced by 2 percent for each 1000 ft above sea level.  
In Canada, the input rating must be derated by 5 percent for altitudes of 2000 ft to 4500 ft above sea level.  
—50—  
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A99119  
Fig. 55—Filling Condensate Trap  
Furnace input rate must be within ±2 percent of input on furnace rating plate.  
1. Determine natural gas orifice size and manifold pressure for correct input.  
a. Obtain yearly heat value average (at installed altitude) from local gas supplier.  
b. Obtain yearly specific gravity average from local gas supplier.  
c. Verify furnace model. Table 13 can only be used for model 355MAV furnaces.  
d. Find installation altitude in Table 13.  
NOTE: For Canada altitudes of 2000 to 4500 ft, use U.S.A. altitudes of 2001 to 3000 ft in Table 13.  
e. Find closest natural gas heat value and specific gravity in Table 13.  
f. Follow heat value and specific gravity lines to point of intersection to find orifice size and low- and high-heat manifold pressure settings  
for proper operation.  
EXAMPLE: (0-2000 ft altitude)  
Heating value = 1050 Btu/cu ft  
Specific gravity = 0.62  
Therefore: Orifice No. 45  
Manifold pressure 3.6-in. wc for high heat  
1.5-in. wc for low heat  
* Furnace is shipped with No. 45 orifices. In this example, all main burner orifices are the correct size and do not need to be changed to  
obtain the proper input rate.  
g. Check and verify burner orifice size in furnace. NEVER ASSUME ORIFICE SIZE; ALWAYS CHECK AND VERIFY.  
2. Adjust manifold pressure to obtain input rate.  
a. Remove burner enclosure front.  
NOTE: Manifold pressure MUST always be measured with the burner box cover REMOVED.  
b. Remove caps that conceal adjustment screws for low- and high-heat gas valve regulators. (See Fig. 56 .)  
c. Move setup switch SW-2 on control center to ON position. (See Fig. 31.) This keeps furnace locked in low-heat operation.  
d. Jumper R and W/W1 thermostat connections on control center to start furnace.  
e. Turn low-heat adjusting screw (5/64 hex Allen wrench) counterclockwise (out) to decrease input rate or clockwise (in) to increase input  
rate.  
—51—  
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Table 13—Model 355MAV Orifice Size and Manifold Pressure for Correct Input  
(Tabulated Data Based on 20,000 Btuh High Heat/13,000 Btuh Low Heat per Burner, Derated 2 Percent for Each 1000 ft Above  
Sea Level)  
SPECIFIC GRAVITY OF NATURAL GAS  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
Manifold  
0.60  
0.62  
0.64  
0.66  
Manifold  
Orifice  
no.  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Orifice  
no.  
Pressure  
3.7/1.5  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.4/1.4  
3.2/1.3  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.2/1.3  
3.6/1.5  
Pressure  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.5  
3.3/1.4  
3.7/1.6  
Pressure  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.7/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
Pressure  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.7/1.6  
3.5/1.5  
3.4/1.4  
3.2/1.3  
3.7/1.6  
3.5/1.5  
3.4/1.4  
Pressure  
3.4/1.4  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.5/1.5  
850  
875  
900  
925  
950  
43  
43  
44  
44  
44  
44  
45  
45  
45  
45  
47  
43  
43  
43  
44  
44  
44  
45  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
44  
45  
45  
45  
45  
42  
43  
43  
43  
44  
44  
44  
44  
45  
45  
45  
42  
42  
43  
43  
44  
44  
44  
44  
45  
45  
45  
0
to  
2000  
975  
1000  
1025  
1050  
1075  
1100  
SPECIFIC GRAVITY OF NATURAL GAS  
0.62  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
0.60  
0.64  
0.66  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Pressure  
3.2/1.4  
3.7/1.5  
3.4/1.5  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.7/1.6  
775  
800  
825  
850  
875  
900  
925  
950  
975  
1000  
1025  
43  
43  
44  
44  
44  
44  
45  
45  
45  
47  
47  
3.8/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.7/1.5  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.6/1.5  
42  
43  
43  
44  
44  
44  
45  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
44  
45  
45  
45  
45  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.4/1.4  
3.2/1.3  
42  
42  
43  
43  
44  
44  
44  
45  
45  
45  
45  
3.4/1.4  
3.2/1.4  
3.7/1.5  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.5/1.5  
3.3/1.4  
42  
42  
43  
43  
43  
44  
44  
44  
45  
45  
45  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.4/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
Altitudes  
2001  
to  
3000  
or  
Canada  
Altitudes  
2000  
to  
4500  
SPECIFIC GRAVITY OF NATURAL GAS  
0.62  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
0.60  
0.64  
0.66  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Pressure  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.2/1.3  
3.6/1.5  
750  
775  
800  
825  
850  
875  
900  
925  
950  
975  
1000  
43  
43  
44  
44  
44  
45  
45  
45  
45  
47  
47  
3.7/1.6  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.6/1.5  
3.5/1.5  
43  
43  
43  
44  
44  
44  
45  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
45  
45  
45  
45  
45  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.5  
3.3/1.4  
3.7/1.6  
42  
43  
43  
43  
44  
44  
44  
45  
45  
45  
45  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.7/1.5  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.4/1.4  
3.2/1.4  
42  
42  
43  
43  
44  
44  
44  
44  
45  
45  
45  
3.5/1.5  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.3  
3.7/1.5  
3.5/1.5  
3.3/1.4  
3001  
to  
4000  
* Orifice numbers 45 are factory installed.  
NOTE: DO NOT set low-heat manifold pressure less than 1.3-in. wc or more than 1.7-in. wc for natural gas. If manifold pressure is outside this  
range, change main burner orifices.  
CAUTION: DO NOT bottom out gas valve regulator adjusting screw. This can result in unregulated manifold pressure  
and result in excess overfire and heat exchanger failures.  
NOTE: If orifice hole appears damaged or it is suspected to have been redrilled, check orifice hole with a numbered drill bit of correct size. Never  
redrill an orifice. A burr-free and squarely aligned orifice hole is essential for proper flame characteristics.  
f. Move setup switch SW-2 to OFF position after completing low-heat adjustment.  
g. Jumper R and W2 thermostat connections on control center. (See Fig. 31.) This keeps furnace locked in high-heat operation.  
h. Turn high-heat adjusting screw (5/64 hex Allen wrench) counterclockwise (out) to decrease input rate or clockwise (in) to increase rate.  
NOTE: DO NOT set high-heat manifold pressure less than 3.2-in. wc or more than 3.8-in. wc for natural gas. If manifold pressure is outside this  
range, change main burner orifices.  
i. When correct input is obtained, replace caps that conceal gas valve regulator adjustment screws. Main burner flame should be clear blue,  
almost transparent. (See Fig. 58.)  
—52—  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Table 13—Model 355MAV Orifice Size and Manifold Pressure for Correct Input (Continued)  
(Tabulated Data Based on 20,000 Btuh High Heat/13,000 Btuh Low Heat per Burner, Derated 2 Percent for Each 1000 ft Above  
Sea Level)  
SPECIFIC GRAVITY OF NATURAL GAS  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
Manifold  
0.60  
0.62  
0.64  
0.66  
Manifold  
Orifice  
no.  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Orifice  
no.  
Pressure  
3.7/1.5  
3.4/1.4  
3.7/1.6  
3.5/1.5  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
Pressure  
3.8/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.6/1.5  
Pressure  
3.2/1.4  
3.7/1.5  
3.4/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.2/1.3  
Pressure  
3.3/1.4  
3.8/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.3  
3.6/1.5  
3.4/1.5  
3.3/1.4  
Pressure  
3.4/1.4  
3.2/1.4  
3.7/1.5  
3.4/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
725  
750  
775  
800  
825  
850  
875  
900  
925  
950  
43  
44  
44  
44  
44  
45  
45  
45  
47  
47  
43  
43  
44  
44  
44  
45  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
45  
45  
45  
45  
42  
43  
43  
44  
44  
44  
44  
45  
45  
45  
42  
42  
43  
43  
44  
44  
44  
45  
45  
45  
4001  
to  
5000  
SPECIFIC GRAVITY OF NATURAL GAS  
0.62  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
0.60  
0.64  
0.66  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Pressure  
3.7/1.6  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.8/1.6  
3.6/1.5  
3.5/1.5  
700  
725  
750  
775  
800  
825  
850  
875  
900  
925  
950  
975  
1000  
43  
43  
44  
44  
44  
45  
45  
45  
47  
47  
48  
48  
48  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.2/1.3  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.6/1.5  
3.4/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
43  
43  
44  
44  
44  
45  
45  
45  
47  
47  
48  
48  
48  
42  
43  
43  
44  
44  
44  
45  
45  
45  
47  
47  
48  
48  
3.2/1.3  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.6/1.5  
3.4/1.5  
3.3/1.4  
3.7/1.5  
3.5/1.5  
3.8/1.6  
3.6/1.5  
42  
43  
43  
44  
44  
44  
45  
45  
45  
45  
47  
47  
48  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.3  
3.6/1.5  
3.4/1.4  
3.7/1.6  
42  
43  
43  
43  
44  
44  
44  
45  
45  
45  
47  
47  
48  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.2/1.4  
3.7/1.5  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.8/1.6  
5001  
to  
6000  
SPECIFIC GRAVITY OF NATURAL GAS  
0.62  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
0.60  
0.64  
0.66  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Pressure  
3.3/1.4  
3.7/1.6  
3.4/1.5  
3.7/1.6  
3.4/1.5  
3.2/1.4  
3.7/1.5  
3.4/1.5  
3.2/1.4  
3.6/1.5  
650  
675  
700  
725  
750  
775  
800  
825  
850  
875  
42  
43  
44  
44  
44  
45  
45  
45  
47  
47  
3.2/1.3  
3.6/1.5  
3.8/1.6  
3.6/1.5  
3.3/1.4  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
42  
43  
43  
44  
44  
44  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
45  
45  
45  
45  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.8/1.6  
3.6/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.3  
42  
42  
43  
43  
44  
44  
44  
45  
45  
45  
3.5/1.5  
3.2/1.4  
3.7/1.6  
3.4/1.4  
3.7/1.6  
3.4/1.5  
3.2/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
42  
42  
43  
43  
44  
44  
44  
45  
45  
45  
3.6/1.5  
3.3/1.4  
3.8/1.6  
3.5/1.5  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
6001  
to  
7000  
* Orifice numbers 45 are factory installed.  
j. Remove jumpers R to W/W1 and R to W2.  
3. Verify natural gas input rate by clocking gas meter.  
NOTE: Be sure all pressure tubing, combustion-air and vent pipes, and burner enclosure front are in place when checking input by clocking gas  
meter.  
a. Calculate high-altitude adjustment (if required).  
CAUTION: DO NOT redrill orifices. Improper drilling (burrs, out-of-round holes, etc.) can cause excessive burner noise  
and misdirection of burner flames. This can result in flame impingement of burners and heat exchangers, causing failures.  
(See Fig. 57.)  
UNITED STATES  
At altitudes above 2000 ft, this furnace has been approved for a 2 percent derate for each 1000 ft above sea level. See Example and Table 14 for  
derate multiplier factor.  
—53—  
Download from Www.Somanuals.com. All Manuals Search And Download.  
Table 13—Model 355MAV Orifice Size and Manifold Pressure for Correct Input (Continued)  
(Tabulated Data Based on 20,000 Btuh High Heat/13,000 Btuh Low Heat per Burner, Derated 2 Percent for Each 1000 ft Above  
Sea Level)  
SPECIFIC GRAVITY OF NATURAL GAS  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
Manifold  
0.60  
0.62  
0.64  
0.66  
Manifold  
Orifice  
no.  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Orifice  
no.  
Pressure  
3.8/1.6  
3.5/1.5  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.6/1.5  
3.4/1.4  
Pressure  
3.3/1.4  
3.7/1.6  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.3  
3.5/1.5  
Pressure  
3.4/1.4  
3.8/1.6  
3.5/1.5  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.5  
Pressure  
3.5/1.5  
3.2/1.4  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.4/1.4  
3.2/1.3  
Pressure  
3.6/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.3/1.4  
625  
650  
675  
700  
725  
750  
775  
800  
825  
850  
43  
43  
44  
44  
44  
45  
45  
45  
47  
47  
42  
43  
43  
44  
44  
45  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
45  
45  
45  
47  
42  
42  
43  
43  
44  
44  
45  
45  
45  
45  
42  
42  
43  
43  
44  
44  
44  
45  
45  
45  
7001  
to  
8000  
SPECIFIC GRAVITY OF NATURAL GAS  
0.62  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
0.60  
0.64  
0.66  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Pressure  
3.3/1.4  
3.6/1.5  
3.4/1.4  
3.6/1.5  
3.3/1.4  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
600  
625  
650  
675  
700  
725  
750  
775  
800  
43  
43  
44  
44  
44  
45  
45  
45  
47  
3.8/1.6  
3.5/1.5  
3.7/1.6  
3.5/1.5  
3.2/1.4  
3.6/1.5  
3.4/1.4  
3.2/1.3  
3.6/1.5  
42  
43  
43  
44  
44  
45  
45  
45  
47  
42  
43  
43  
44  
44  
44  
45  
45  
45  
3.4/1.4  
3.8/1.6  
3.5/1.5  
3.7/1.6  
3.4/1.5  
3.2/1.4  
3.6/1.5  
3.4/1.4  
3.2/1.3  
42  
42  
43  
44  
44  
44  
45  
45  
45  
3.5/1.5  
3.2/1.4  
3.6/1.5  
3.8/1.6  
3.6/1.5  
3.3/1.4  
3.8/1.6  
3.5/1.5  
3.3/1.4  
42  
42  
43  
43  
44  
44  
44  
45  
45  
3.6/1.5  
3.3/1.4  
3.7/1.6  
3.4/1.5  
3.7/1.6  
3.4/1.4  
3.2/1.4  
3.6/1.5  
3.4/1.4  
Altitudes  
8001  
to  
9000  
SPECIFIC GRAVITY OF NATURAL GAS  
0.62  
ALTITUDE  
RANGE  
(FT)  
AVG GAS  
HEAT VALUE  
(BTU/CU FT)  
0.58  
0.60  
0.64  
0.66  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Orifice  
no.  
Manifold  
Pressure  
Pressure  
3.2/1.4  
3.6/1.5  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.4/1.5  
3.2/1.4  
3.6/1.5  
575  
600  
625  
650  
675  
700  
725  
750  
775  
43  
43  
44  
44  
44  
45  
45  
47  
47  
3.8/1.6  
3.5/1.5  
3.7/1.6  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.3/1.4  
3.7/1.6  
3.5/1.5  
42  
43  
44  
44  
44  
45  
45  
45  
47  
42  
43  
43  
44  
44  
45  
45  
45  
47  
3.3/1.4  
3.7/1.6  
3.5/1.5  
3.7/1.5  
3.4/1.4  
3.8/1.6  
3.6/1.5  
3.3/1.4  
3.7/1.6  
42  
42  
43  
44  
44  
44  
45  
45  
45  
3.5/1.5  
3.2/1.3  
3.6/1.5  
3.8/1.6  
3.5/1.5  
3.3/1.4  
3.7/1.6  
3.4/1.5  
3.2/1.4  
42  
42  
43  
43  
44  
44  
45  
45  
45  
3.6/1.5  
3.3/1.4  
3.7/1.6  
3.4/1.4  
3.6/1.5  
3.4/1.4  
3.8/1.6  
3.5/1.5  
3.3/1.4  
9001  
to  
10,000  
*Orifice numbers 45 are factory installed.  
CANADA  
At installation altitudes from 2000 to 4500 ft, this furnace must be derated 5 percent by an authorized Gas Conversion Station or Dealer. To  
determine correct input rate for altitude, see example above and use 0.95 as derate multiplier factor.  
b. Reinstall burner box cover.  
NOTE: Clocking gas input rate MUST always be performed with the burner box cover INSTALLED.  
c. Check that gas valve adjustment caps are in place for proper input to be clocked.  
d. Obtain yearly heat value average for local gas supply.  
NOTE: Be sure heating value of gas used for calculations is correct for your altitude. Consult local gas utility for altitude adjustment of gas heating  
value.  
e. Check and verify orifice size in furnace. NEVER ASSUME THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.  
f. Turn off all other gas appliances and pilots.  
g. Move setup switch SW-2 to ON position. (See Fig. 31.) This keeps furnace locked in low-heat operation.  
h. Jumper R to W/W1.  
i. Let furnace run for 3 minutes in low-heat operation.  
j. Measure time (in sec) for gas meter to complete 1 revolution. Note reading.  
k. Refer to Table 15 for cubic ft of gas per hr.  
l. Multiply gas rate cu ft/hr by heating value (Btu/cu ft).  
—54—  
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LOW-FIRE  
ON/OFF  
SWITCH  
ADJUSTMENT  
ALLEN SCREW  
(UNDER CAP)  
HIGH-FIRE  
ADJUSTMENT  
ALLEN SCREW  
(UNDER CAP)  
INLET  
PRESSURE  
TAP  
O
F
F
ON  
BURNER  
ENCLOSURE  
REFERENCE  
PRESSURE TAP  
MANIFOLD  
PRESSURE  
TAP  
A97386  
Fig. 56—Redundant Automatic Gas Valve  
BURNER  
ORIFICE  
A93059  
Fig. 57—Burner Orifice  
m. Move setup switch SW-2 to OFF position and jumper R and W2 thermostat connections. (See Fig. 31.) This keeps furnace locked in  
high-heat operation. Repeat items h through k for high-heat operation.  
EXAMPLE: (High-heat operation at 0-2000 ft altitude)  
Furnace input from rating plate is 100,000 Btuh.  
Btu heating input = Btu/cu ft X cu ft/hr  
Heating value of gas = 975 Btu/cu ft  
Time for 1 revolution of 2-cu ft dial = 70 sec  
Gas rate = 103 cu ft/hr (from Table 15)  
Btu heating input = 103 X 975 = 100,425 Btuh. In this example, the orifice size and manifold pressure adjustment is within ±2 percent of  
the furnace input rate.  
NOTE: Measured gas inputs (high heat and low heat) must be within ±2 percent of that stated on furnace rating plate when installed at sea level  
or derated per that stated above when installed at higher altitudes.  
n. Remove jumper across R, W/W1, and W2 thermostat connections to terminate call for heat.  
B. Set Temperature Rise  
CAUTION: Temperature rise must be within limits specified on unit rating plate. Recommended operation is at  
midpoint of rise or above. Failure to follow this caution may result in overheating the heat exchangers or condensing flue  
gases in heat exchanger areas not designed for condensate.  
—55—  
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BURNER FLAME  
BURNER  
MANIFOLD  
Fig. 58—Burner Flame  
EXAMPLE:  
A89020  
100,000 Btuh input furnace installed at 4300 ft.  
Derate  
Multiplier  
Factor  
Furnace Input Rate  
at Installation  
Altitude  
Furnace Input Rate  
at Sea Level  
X
X
=
=
100,000  
0.91  
91,000  
Table 14—Altitude Derate Multiplier for U.S.A.  
ALTITUDE  
(FT)  
PERCENT  
OF DERATE  
DERATE MULTIPLIER  
FACTOR FOR U.S.A.*  
0–2000  
0
4–6  
6–8  
8–10  
10–12  
12–14  
14–16  
16–18  
18–20  
1.00  
0.95  
0.93  
0.91  
0.89  
0.87  
0.85  
0.83  
0.81  
2001–3000  
3001–4000  
4001–5000  
5001–6000  
6001–7000  
7001–8000  
8001–9000  
9001–10,000  
* Derate multiplier factor is based on midpoint altitude for altitude range.  
Furnace must operate within the temperature rise ranges specified on the furnace rating plate. Determine the air temperature as follows:  
1. Place thermometers in return and supply ducts as close to furnace as possible. Be sure thermometers do not ’see’ heat exchangers so that  
radiant heat does not affect thermometer readings. This practice is particularly important with straight run ducts.  
2. When thermometer readings stabilize, subtract return-air temperature from supply-air temperature to determine air temperature rise.  
NOTE: Temperature rise can be determined for low-fire operation by placing setup switch SW-2 on control center in ON position. For high-heat  
operation, place setup switch SW-2 in OFF position and jumper R-W2 on control center. DO NOT forget to return setup switch to OFF position  
and remove R-W2 jumper upon completion of testing. (See Fig. 31 for switch and terminal location.)  
3. This furnace is capable of automatically providing proper airflow to maintain the temperature rise within the range specified on unit rating  
plate. If temperature rise is outside this range, proceed as follows:  
a. Check gas input for low- and high-heat operation.  
b. Check derate for altitude if applicable.  
c. Check all return and supply ducts for excessive restrictions causing static pressure greater than 0.5-in. wc.  
d. Ensure bypass humidifier switch (BPH) setup switch SW-3 on control center is in ON position when a bypass humidifier is used. (See  
Fig. 31 for switch location.)  
e. Check Troubleshooting Guide for Variable-Speed 2-Stage Electronic Condensing Furnaces.  
C. Set Thermostat Heat Anticipator  
The thermostat heat anticipator must be set to match the amp draw of components in the R-W/W1 circuit. Accurate amp draw measurements can  
be obtained at the thermostat subbase terminals R and W.  
Fig. 59 illustrates an easy method of obtaining thermostat amp draw measurements. The amp reading should be taken after blower motor has started  
and furnace is operating in low heat.  
1. To operate furnace in low heat, turn setup switch SW-2 to ON position (See Fig. 31.) and connect ammeter leads across thermostat subbase  
R-W.  
—56—  
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Table 15—Gas Rate (Cu Ft/Hr)  
SIZE OF TEST DIAL  
SIZE OF TEST DIAL  
SECONDS  
FOR 1  
REVOLUTION  
SECONDS  
FOR 1  
REVOLUTION  
1
2
5
1
2
5
Cu Ft  
Cu Ft  
Cu Ft  
Cu Ft  
Cu Ft  
Cu Ft  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
49  
360  
327  
300  
277  
257  
240  
225  
212  
200  
189  
180  
171  
164  
157  
150  
144  
138  
133  
129  
124  
120  
116  
113  
109  
106  
103  
100  
97  
95  
92  
90  
88  
86  
84  
82  
80  
78  
76  
75  
73  
720  
655  
600  
555  
514  
480  
450  
424  
400  
379  
360  
343  
327  
313  
300  
288  
277  
267  
257  
248  
240  
232  
225  
218  
212  
206  
200  
195  
189  
185  
180  
176  
172  
167  
164  
160  
157  
153  
150  
147  
1800  
1636  
1500  
1385  
1286  
1200  
1125  
1059  
1000  
947  
900  
857  
818  
783  
750  
720  
692  
667  
643  
621  
600  
581  
563  
545  
529  
514  
500  
486  
474  
462  
450  
439  
429  
419  
409  
400  
391  
383  
375  
367  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
62  
64  
66  
68  
70  
72  
74  
76  
78  
80  
82  
84  
86  
88  
90  
92  
94  
96  
72  
71  
69  
68  
67  
65  
64  
63  
62  
61  
60  
58  
56  
54  
53  
51  
50  
48  
47  
46  
45  
44  
43  
42  
41  
40  
39  
38  
38  
37  
36  
35  
35  
34  
33  
33  
32  
31  
30  
144  
141  
138  
136  
133  
131  
129  
126  
124  
122  
120  
116  
112  
109  
106  
103  
100  
97  
95  
92  
90  
88  
86  
84  
82  
80  
78  
76  
75  
74  
72  
71  
69  
68  
67  
65  
64  
62  
360  
355  
346  
340  
333  
327  
321  
316  
310  
305  
300  
290  
281  
273  
265  
257  
250  
243  
237  
231  
225  
220  
214  
209  
205  
200  
196  
192  
188  
184  
180  
178  
173  
170  
167  
164  
161  
155  
150  
98  
100  
102  
104  
106  
108  
110  
112  
116  
120  
60  
2. See thermostat manufacturer’s instructions for adjusting the heat anticipator and for varying heating cycle length.  
NOTE: When using an electronic thermostat, set cycle rate for 3 cycles per hr.  
3. Return setup switch SW-2 to OFF position and replace thermostat on subbase.  
PROCEDURE 6—CHECK SAFETY CONTROLS  
A. Check Primary Limit Control  
This control shuts off the combustion control system and energizes the air-circulating blower motor if furnace overheats.  
1. The recommended method of checking this limit control is to gradually block off return air after furnace has been operating for a period  
of at least 5 minutes.  
2. As soon as limit control has shut off burners, a 33 fault code will appear on control center.  
3. The return-air opening should be unblocked to permit normal air circulation.  
By using this method to check the limit control, it can be established that the limit is functioning properly and the furnace will operate safely if  
there is a restricted return-air supply or motor failure. If the limit control does not function during this test, the cause must be determined and  
corrected.  
B. Check Pressure Switches  
This control proves operation of the draft inducer. Check switch operation as follows:  
1. Turn off 115-v power to furnace.  
2. Remove control access door and disconnect inducer motor 12-pin wire harness at inducer motor.  
—57—  
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THERMOSTAT SUBBASE  
TERMINALS WITH  
THERMOSTAT REMOVED  
(ANITICIPATOR, CLOCK, ETC.,  
MUST BE OUT OF CIRCUIT.)  
HOOK-AROUND  
AMMETER  
R
Y
W
G
10 TURNS  
FROM UNIT 24-V  
CONTROL TERMINALS  
0.5 AMPS FOR THERMOSTAT  
ANTICIPATOR SETTING  
5.0 AMPS ON AMMETER  
10 TURNS AROUND JAWS  
=
EXAMPLE:  
A96316  
Fig. 59—Amp Draw Check with Ammeter  
3. Turn on 115-v power to furnace.  
4. Set thermostat to call for heat. When pressure switches are functioning properly, fault code 42 will flash on control center approximately  
10 sec after thermostat switch is closed. If either a fault code 31 or 32 is flashed when ICM inducer motor is disconnected, the furnace will  
shut itself down immediately. Determine the reason pressure switches did not function properly and correct the condition.  
5. Turn off 115-v power to furnace.  
6. Reconnect inducer motor wire harness. Reinstall furnace access door.  
7. Turn on 115-v power to furnace.  
8. Reset thermostat to desired temperature.  
PROCEDURE 7—CHECKLIST  
1. Put away tools and instruments. Clean up debris.  
2. Verify manual reset switch has continuity.  
3. Verify that blower and control access doors are properly installed.  
4. Cycle test furnace with room thermostat.  
5. Check operation of accessories per manufacturer’s instructions.  
6. Review User’s Guide with owner.  
7. Leave literature packet near furnace.  
—58—  
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CHECKLIST—INSTALLATION  
Load Calculation  
Condensate Drain  
_______  
_______  
_______  
_______  
_______  
Unit Level or Pitched Forward  
_______  
_______  
_______  
Heating Load (Btuh)  
Cooling Load (Btuh)  
Furnace Model Selection  
Internal Tubing Connections Freeof Kinks and Traps  
External Drain Connection Leak tight and Sloped  
Condensate Trap Primed before Start-Up  
Heat Tape Installed if Required  
COMBUSTION AND VENT PIPING  
Terminal Location  
CHECKLIST—START-UP  
_______  
_______  
______  
______  
______  
______  
______  
______  
Roof or Sidewall  
Termination Kit — 2 Pipe or Concentric  
Combustion-Air Pipe Length  
Combustion-Air Elbow Quantity  
Vent Pipe Elbow Quantity  
Pipe Diameter Determined from  
Sizing Table  
______  
______  
Gas Input Rate(Set Within 2 percent of RatingPlate)  
Temperature Rise Adjusted  
Pipe Sloped to Furnace  
Pipe Insulation  
Thermostat Anticipator  
______  
______  
Over Ceilings  
Low-Ambient Exposed Pipes  
______  
______  
Anticipator Setting Adjusted or  
Cycle Rate (3 Cycles per Hr)Selected  
Safety Controls Check Operaton  
______  
______  
Primary Limit  
Pressure Switch  
—59—  
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© 2002 CAC/BDP 7310 W. Morris St., Indianapolis, IN 46231  
355m4011  
—60—  
Book/Tab: 1/6  
Catalog No. 5335-518  
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