Johnson Controls Furnace CM8M CMLMMP User Manual

INSTALLATION MANUAL  
RESIDENTIAL GAS FURNACE  
WITH PSC MOTOR  
EFFICIENCY  
RATING  
CERTIFIED  
MODELS:  
TM8M/TMLM*MP, YM8M/YMLM*MP,  
CM8M/CMLM*MP, LM8M/LMLM*MP  
ISO 9001  
Certified Quality  
Management System  
(80% Modulating Multi-position / Low NOx)  
LIST OF SECTIONS  
SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1  
DUCTWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
GAS PIPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
ELECTRICAL POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
TWINNING AND STAGING . . . . . . . . . . . . . . . . . . . . . . . . . . . 18  
VENT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18  
START-UP AND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . 20  
SAFETY CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24  
NORMAL OPERATION AND DIAGNOSTICS . . . . . . . . . . . . . 25  
REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . 27  
REPLACEMENT PART CONTACT INFORMATION . . . . . . . . 27  
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
LIST OF FIGURES  
Duct Attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Vertical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Coil Flange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Horizontal Right Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7  
Horizontal Left Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
PC Series Upflow Coil Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
Horizontal Left or Right application (Right Shown) . . . . . . . . . . . . . . 8  
Combustible Floor Base Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
Horizontal Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
Typical Attic Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
Typical Suspended Furnace / Crawl Space Installation . . . . . . . . . . . 9  
Downflow Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
Downflow Installation - Gas Valve Rotation . . . . . . . . . . . . . . . . . . . . 9  
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
Side Return Cutout Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11  
Upflow/Downflow Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11  
Horizontal Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11  
Electrical Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
Thermostat Chart - Single Stage Air Conditioner –  
Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .14  
Thermostat Chart - Two Stage Air Conditioner –  
Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .15  
Thermostat Chart - Two Stage Air Conditioner with Single Stage  
Thermostat – Variable Speed or PSC Modulating Furnace . . . . . . .16  
Thermostat Chart - Single Stage Heat Pump –  
Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .17  
Thermostat Chart - Single Stage Heat Pump –  
Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .18  
Thermostat Chart - Two Stage Heat Pump –  
Variable Speed or PSC Modulating Furnace . . . . . . . . . . . . . . . . . .19  
Combustion Air Inducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20  
Combustion Airflow Path Through The Furnace  
Casing to the Burner Compartment . . . . . . . . . . . . . . . . . . . . . . . . .20  
Outside and Ambient Combustion Air . . . . . . . . . . . . . . . . . . . . . . . .21  
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25  
Furnace Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26  
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30  
LIST OF TABLES  
Unit Clearances to Combustibles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Coil Projection Dimensions - PC Series Coils . . . . . . . . . . . . . . . . . . 6  
Cabinet and Duct Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
Recommended Filter Sizes (High Velocity 600 FPM) . . . . . . . . . . . . 8  
High Altitude Orifices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
Ratings & Physical / Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . 10  
Estimated Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Unconfined Space Minimum Area in Square Inch . . . . . . . . . . . . . .19  
Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19  
Gas Rate (CU FT/HR) at Full Input . . . . . . . . . . . . . . . . . . . . . . . . . .22  
Inlet Gas Pressure Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23  
Nominal Manifold Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23  
Cooling Airflow - A/C Capacity in Tons . . . . . . . . . . . . . . . . . . . . . . .24  
These high efficiency, compact units employ induced combustion, reli-  
able hot surface ignition and high heat transfer aluminized tubular heat  
exchangers. The units are factory shipped for installation in upflow or  
horizontal applications and may be converted for downflow applica-  
tions.  
DANGER indicates an imminently hazardous situation, which, if not  
avoided, will result in death or serious injury.  
WARNING indicates a potentially hazardous situation, which, if not  
avoided, could result in death or serious injury.  
CAUTION indicates a potentially hazardous situation, which, if not  
avoided may result in minor or moderate injury. It is also used to  
alert against unsafe practices and hazards involving only property dam-  
age.  
These furnaces are designed for residential installation in a basement,  
closet, alcove, attic, recreation room or garage and are also ideal for  
commercial applications. All units are factory assembled, wired and  
tested to assure safe dependable and economical installation and oper-  
ation.  
These units are Category I listed and may be common vented with  
another gas appliance as allowed by the National Fuel Gas Code.  
Improper installation may create a condition where the operation of  
the product could cause personal injury or property damage.  
Improper installation, adjustment, alteration, service or mainte-  
nance can cause injury or property damage. Failure to carefully  
read and follow all instructions in this manual can result in fur-  
nace malfunction, death, personal injury and/or property dam-  
age. Only a qualified contractor, installer or service agency should  
install this product.  
SECTION I: SAFETY  
This is a safety alert symbol. When you see this symbol on  
labels or in manuals, be alert to the potential for personal  
injury.  
Understand and pay particular attention to the signal words DANGER,  
WARNING, or CAUTION.  
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These instructions cover minimum requirements and conform to exist-  
ing national standards and safety codes. In some instances these  
instructions exceed certain local codes and ordinances, especially  
those who have not kept up with changing residential and non-HUD  
modular home construction practices. These instructions are required  
as a minimum for a safe installation.  
The furnace area must not be used as a broom closet or for any  
other storage purposes, as a fire hazard may be created. Never  
store items such as the following on, near or in contact with the fur-  
nace.  
1. Spray or aerosol cans, rags, brooms, dust mops, vacuum  
cleaners or other cleaning tools.  
FOR FURNACES INSTALLED IN THE COMMON-  
WEALTH OF MASSACHUSETTS ONLY  
2. Soap powders, bleaches, waxes or other cleaning com-  
pounds; plastic items or containers; gasoline, kerosene, ciga-  
rette lighter fluid, dry cleaning fluids or other volatile fluid.  
3. Paint thinners and other painting compounds.  
For all side wall horizontally vented gas fueled equipment installed in  
every dwelling, building or structure used in whole or in part for resi-  
dential purposes, including those owned or operated by the Com-  
monwealth and where the side wall exhaust vent termination is less  
than seven (7) feet above finished grade in the area of the venting,  
including but not limited to decks and porches, the following require-  
ments shall be satisfied:  
4. Paper bags, boxes or other paper products  
Never operate the furnace with the blower door removed. To  
do so could result in serious personal injury and/or equipment  
damage.  
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At  
the time of installation of the side wall horizontal vented gas  
fueled equipment, the installing plumber or gasfitter shall  
observe that a hard wired carbon monoxide detector with an  
alarm and battery back-up is installed on the floor level where  
the gas equipment is to be installed. In addition, the installing  
plumber or gasfitter shall observe that a battery operated or  
hard wired carbon monoxide detector with an alarm is installed  
on each additional level of the dwelling, building or structure  
served by the side wall horizontal vented gas fueled equipment.  
It shall be the responsibility of the property owner to secure the  
services of qualified licensed professionals for the installation of  
hard wired carbon monoxide detectors  
CODES AND STANDARDS  
Follow all national, local codes and standards in addition to this installa-  
tion manual. The installation must comply with regulations of the serv-  
ing gas supplier, local building, heating, plumbing, and other codes. In  
absence of local codes, the installation must comply with the national  
codes listed below and all authorities having jurisdiction.  
In the United States and Canada, follow all codes and standards for the  
following, using the latest edition available:  
STEP 1 -Safety  
US: National Fuel Gas Code (NFGC) NFPA 54/ANSI Z223.1 and  
the Installation Standards, Warm Air Heating and Air Conditioning  
Systems ANSI/NFPA 90B  
CANADA: CAN/CGA-B149.1 National Standard of Canada. Natu-  
ral Gas and Propane Installation Codes (NSCNGPIC)  
a. In the event that the side wall horizontally vented gas  
fueled equipment is installed in a crawl space or an attic,  
the hard wired carbon monoxide detector with alarm and  
battery back-up may be installed on the next adjacent floor  
level.  
STEP 2 -General Installation  
US: Current edition of the NFGC and NFPA 90B. For copies, con-  
tact the  
b. In the event that the requirements of this subdivision can  
not be met at the time of completion of installation, the  
owner shall have a period of thirty (30) days to comply with  
the above requirements; provided, however, that during  
said thirty (30) day period, a battery operated carbon mon-  
oxide detector with an alarm shall be installed.  
National Fire Protection Association Inc.  
Batterymarch Park  
Quincy, MA 02269  
or for only the NFGC, contact the  
American Gas Association,  
400 N. Capital, N.W.  
2. APPROVED CARBON MONOXIDE DETECTORS. Each car-  
bon monoxide detector as required in accordance with the  
above provisions shall comply with NFPA 720 and be ANSI/UL  
2034 listed and IAS certified.  
Washington DC 20001  
3. SIGNAGE. A metal or plastic identification plate shall be perma-  
nently mounted to the exterior of the building at a minimum  
height of eight (8) feet above grade directly in line with the  
exhaust vent terminal for the horizontally vented gas fueled  
heating appliance or equipment. The sign shall read, in print  
size no less than one-half (1/2) inch in size, "GAS VENT  
DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUC-  
TIONS".  
CANADA: NSCNGPIC. For a copy contact:  
Standard Sales, CSA International  
178 Rexdale Boulevard  
Etobicoke, (Toronto) Ontario Canada M9W 1RS  
STEP 3 -Combustion and Ventilation Air  
US: Section 5.3 of the NFGC, air for Combustion and Ventilation  
CANADA: Part 7 of NSCNGPIC, Venting Systems and Air Supply  
for Appliances  
4. INSPECTION. The state or local gas inspector of the side wall  
horizontally vented gas fueled equipment shall not approve the  
installation unless, upon inspection, the inspector observes car-  
bon monoxide detectors and signage installed in accordance  
with the provisions of 248 CMR 5.08(2)(a)1 through 4.  
STEP 4 -Duct Systems  
US and CANADA: Air Conditioning Contractors Association  
(ACCA) Manual D, Sheet Metal and Air Conditioning Contractors  
Association National Association (SMACNA), or American Soci-  
ety of Heating, Refrigeration, and Air Conditioning Engineers  
(ASHRAE) 1997 Fundamentals Handbook Chapter 32.  
INSPECTION  
STEP 5 -Acoustical Lining and Fibrous Glass Duct  
As soon as a unit is received, it should be inspected for possible dam-  
age during transit. If damage is evident, the extent of the damage  
should be noted on the carrier’s freight bill. A separate request for  
inspection by the carrier’s agent should be made in writing. Also, before  
installation, the unit should be checked for screws or bolts which may  
have loosened in transit. There are no shipping or spacer brackets  
which need to be removed from the interior of this unit.  
US and CANADA: Current edition of SMACNA and NFPA 90B as  
tested by UL Standard 181 for Class I Rigid Air Ducts  
STEP 6 -Gas Piping and Gas Pipe Pressure Testing  
US: NFGC; chapters 2, 3, 4, & 9 and National Plumbing Codes  
CANADA: NSCNGPIC Part 5  
STEP 7 -Electrical Connections  
US: National Electrical Code (NEC) ANSI/NFPA 70  
CANADA: Canadian Electrical Code CSA C22.1  
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2. Do not allow return air temperature to be below 55º F (13° C) for  
extended periods. To do so may cause condensation to occur in  
the main heat exchanger, leading to premature heat exchanger  
failure.  
FURNACE LOCATION AND CLEARANCES  
The furnace shall be located using the following guidelines:  
1. Where a minimum amount of air intake/vent piping and elbows will  
be required.  
Clearances for access/service:  
2. As centralized with the air distribution as possible.  
3. Where adequate combustion air will be available.  
Ample clearances should be provided to permit easy access to the unit.  
The following minimum clearances are recommended:  
4. Where it will not interfere with proper air circulation in the confined  
space.  
1. Twenty-four (24) inches (61 cm) between the front of the furnace  
and an adjacent wall or another appliance, when access is  
required for servicing and cleaning.  
5. Where the outdoor vent terminal will not be blocked or restricted.  
Refer to “VENT CLEARANCES” located in SECTION VII of these  
instructions. These minimum clearances must be maintained in  
the installation.  
2. Eighteen (18) inches (46 cm) at the side where access is required  
for passage to the front when servicing or for inspection or replace-  
ment of flue/vent connections.  
6. Where the unit will be installed in a level position with no more than  
1/4” (6.4 mm) slope side-to-side and front-to-back.  
In all cases, accessibility clearances shall take precedence over clear-  
ances for combustible materials where accessibility clearances are  
greater.  
Installation in freezing temperatures:  
1. Furnace shall be installed in an area where ventilation facilities  
provide for safe limits of ambient temperature under normal oper-  
ating conditions.  
Installation in a residential garage:  
A gas-fired furnace for installation in a residential garage must be  
installed so the burner(s) and the ignition source are located not less  
than 18 inches (46 cm) above the floor, and the furnace must be located  
or protected to avoid physical damage by vehicles.  
Table 1: Unit Clearances to Combustibles (All Dimensions in Inches, and All Surfaces Identified with the Unit in an Upflow Configuration)  
Top  
Front  
Rear  
Left Side  
In. (cm)  
0 (0.0)  
Right Side  
In. (cm)  
0 (0.0)  
Flue  
Floor/  
Bottom  
Line  
Contact  
Application  
Closet  
Alcove  
Attic  
In. (cm) In. (cm) In. (cm)  
In. (cm)  
Upflow B-Vent  
1 (2.5)  
1 (2.5)  
1 (2.5)  
3 (7.6)  
3 (7.6)  
3 (7.6)  
0 (0.0)  
0 (0.0)  
0 (0.0)  
1 (2.5) Combustible  
1 (25.4)1  
1 (2.5)  
Yes  
Yes  
No  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
No  
Downflow B-Vent  
Horizontal B-Vent  
0 (0.0)  
0 (0.0)  
Yes2  
0 (0.0)  
0 (0.0)  
1 (2.5) Combustible  
1. Special floor base or air conditioning coil required for use on combustible floor.  
2. Line contact only permitted between lines formed by the intersection of the rear panel and side panel (top in horizontal position) of the furnace jacket and building  
joists, studs or framing.  
When replacing an existing furnace, if the existing plenum is not the  
same size as the new furnace then the existing plenum must be  
removed and a new plenum installed that is the proper size for the new  
SECTION II: DUCTWORK  
DUCTWORK GENERAL INFORMATION  
The duct system’s design and installation must:  
furnace. If the plenum is shorter than 12” (30.5 cm) the turbulent air flow  
may cause the limit controls not to operate as designed, or the limit con-  
trols may not operate at all.  
1. Handle an air volume appropriate for the served space and within  
the operating parameters of the furnace specifications.  
The duct system is a very important part of the installation. If the duct  
system is improperly sized the furnace will not operate properly.  
The ducts attached to the furnace plenum, should be of sufficient size  
so that the furnace operates at the specified external static pressure  
and within the air temperature rise specified on the nameplate.  
2. Be installed in accordance of National Fire Protection Association  
as outlined in NFPA standard 90B (latest editions) or applicable  
national, provincial, state, and local fire and safety codes.  
3. Create a closed duct system. For residential and Non-HUD Modu-  
lar Home installations, when a furnace is installed so that the sup-  
ply ducts carry air circulated by the furnace to areas outside the  
space containing the furnace, the return air shall also be handled  
by a duct(s) sealed to the furnace casing and terminating outside  
the space containing the furnace.  
The minimum plenum height is 12” (30.5 cm). The furnace will not  
operate properly on a shorter plenum height. The minimum recom-  
mended rectangular duct height is 4 inches (10 cm) attached to the  
plenum.  
4. Complete a path for heated or cooled air to circulate through the  
air conditioning and heating equipment and to and from the condi-  
tioned space.  
If a matching cooling coil is used, it may be placed directly on the fur-  
nace outlet and sealed to prevent leakage. If thermoplastic evaporator  
‘A’ coil drain pans are to be installed in the upflow/horizontal configura-  
tion, then extra 2” minimum spacing may be needed to ensure against  
drain pan distortion.  
The cooling coil must be installed in the supply air duct, down-  
stream of the furnace. Cooled air may not be passed over the heat  
exchanger.  
When the furnace is used with a cooling coil, the coil must be installed  
parallel with, or in the supply air side of the furnace to avoid condensa-  
tion in the primary heat exchanger. When a parallel flow arrangement is  
used, dampers or other means used to control airflow must be ade-  
quate to prevent chilled air from entering the furnace. If manually oper-  
ated, the damper must be equipped with means to prevent the furnace  
or the air conditioner from operating unless the damper is in full heat or  
cool position.  
The duct system must be properly sized to obtain the correct airflow  
for the furnace size that is being installed.  
Refer to Table 6, "Ratings & Physical / Electrical Data" or the fur-  
nace rating plate for the correct rise range and static pressures.  
If the ducts are undersized, the result will be high duct static pres-  
sures and/or high temperature rises which can result in a heat  
exchanger OVERHEATING CONDITION. This condition can result  
in premature heat exchanger failure, which can result in personal  
injury, property damage, or death.  
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DUCT FLANGES  
COIL/FURNACE ASSEMBLY - MC/FC/PC SERIES  
COILS  
Four flanges are provided to attach ductwork to the furnace. These  
flanges are rotated down for shipment. In order to use the flanges,  
remove the screw holding an individual flange, rotate the flange so it is  
in the upward position and reinstall the screw then repeat this for all 4  
flanges.  
If the flanges are not used, they should remain in the rotated down posi-  
tion as shipped.  
Factory  
installed  
For duct attachment,  
if needed.  
UPFLOW  
FIGURE 2: Vertical Applications  
DOWNFLOW  
FIGURE 1: Duct Attachment  
FURNACE ASSEMBLY - MC & FC SERIES COILS  
These coils are factory shipped for installation in either upflow or down-  
flow applications with no conversion.  
DUCTWORK INSTALLATION AND SUPPLY PLENUM  
CONNECTION - UPFLOW/HORIZONTAL  
Position the coil casing over or under the furnace opening as shown in  
Figure 2, "Vertical Applications" after configuring coil flanges as  
required see “Coil Flange” section below.  
Attach the supply plenum to the furnace outlet. The use of  
an approved flexible duct connector is recommended on all  
installations. This connection should be sealed to prevent  
air leakage. The sheet metal should be crosshatched to  
eliminate any popping of the sheet metal when the indoor  
fan is energized.  
COIL FLANGE INSTALLATION  
The coils include removable flanges to allow proper fit up with furnaces  
having various inlet and outlet flange configurations. The two flanges  
are attached to the top of the coil in the factory during production. For  
proper configuration of flanges refer to Figure 3, "Coil Flange".  
FLOOR BASE AND DUCTWORK INSTALLATION -  
DOWNFLOW  
Installations on combustible material or directly on any  
floors must use a combustible floor base shown in Figure 8,  
"Combustible Floor Base Accessory". Follow the instruc-  
tions supplied with the combustible floor base accessory.  
This combustible floor base can be replaced with a match-  
ing cooling coil, properly sealed to prevent leaks. Follow the  
instructions supplied with the cooling coil cabinet for install-  
ing the cabinet to the duct connector. Plug intake and vent  
pipe holes in bottom panel and move grommet to desired  
vent side exit.  
Downflow Air Conditioning Coil Cabinet  
FACTORY  
FLANGE  
LOCATION  
(Used for upflow  
or horizontal  
The furnace should be installed with coil cabinet part number specifi-  
cally intended for downflow application. If a matching cooling coil is  
used, it may be placed directly on the furnace outlet and sealed to pre-  
vent leakage. For details of the coil cabinet dimensions and installation  
requirements, refer to the installation instructions supplied with the coil  
cabinet.  
right installations)  
ALTERNATE  
FLANGE LOCATION  
(Used for downflow or  
horizontal left installations)  
Attach the air conditioning coil cabinet to the duct connector, and then  
position the furnace on top of the coil cabinet. The connection to the fur-  
nace, air conditioning coil cabinet, duct connector, and supply air duct  
must be sealed to prevent air leakage.  
FIGURE 3: Coil Flange  
FURNACE ASSEMBLY - MC SERIES COILS ONLY  
MC coils are supplied ready to be installed in a horizontal position. A  
horizontal pan is factory installed. MC coils should be installed in all hor-  
izontal applications with the horizontal drain pan side down.  
COIL INSTALLATION  
Mounting Plate  
On all installations without a coil, a removable access panel is rec-  
ommended in the outlet duct such that smoke or reflected light  
would be observable inside the casing to indicate the presence of  
leaks in the heat exchanger. This access cover shall be attached in  
such a manner as to prevent leaks.  
Furnace  
FIGURE 4: Horizontal Right Application  
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For horizontal left hand applications no conversion is required to an MC  
coil when used with a downflow/horizontal furnace. A mounting plate,  
supplied with every coil should always be installed on the side desig-  
nated as top side. See Figures 4 & 5.  
CRITICAL COIL PROJECTION  
The coil assembly must be located in the duct such that a minimum dis-  
tance is maintained between the top of the coil and the top of the duct.  
Refer to Table 2, "Coil Projection Dimensions - PC Series Coils".  
COIL / FURNACE ASSEMBLY - HC SERIES COILS  
Mounting Plate  
These coils are supplied ready to be installed in a right hand position or  
a left hand position. When used in conjunction with a horizontal furnace  
(blow through) application, the coil should be oriented with the opening  
of the “A” coil closest to the furnace. See Figures 7.  
Furnace  
NOTE: Each coil is shipped with an external tie plate that should be  
used to secure the coil to the furnace. It should be installed on the back  
side of the coil using the dimpled pilot holes. See Figures 7.  
FIGURE 5: Horizontal Left Application  
Use tie plate  
supplied with coil  
FURNACE ASSEMBLY - PC SERIES COILS  
These upflow coils are designed for installation on top of upflow fur-  
naces only.  
If the coil is used with a furnace of a different size, use a 45° transition  
to allow proper air distribution through the coil.  
1. Position the coil casing over the furnace opening as shown in Fig-  
ure 6, "PC Series Upflow Coil Installation".  
Gas Furnace  
2. Place the ductwork over the coil casing flange and secure.  
3. Check for air leakage between the furnace and coil casing and  
seal appropriately.  
FIGURE 7: Horizontal Left or Right application (Right Shown)  
DOWNFLOW DUCT CONNECTORS  
All downflow installations must use a suitable duct connector approved  
by the furnace manufacturer for use with this furnace. The duct connec-  
tors are designed to be connected to the rectangular duct under the  
floor and sealed. Refer to the instructions supplied with the duct con-  
nector for proper installation. Refer to the separate accessory parts list  
at the end of these instructions for the approved accessory duct con-  
nectors.  
Do not drill any holes or drive any screws into the front duct  
flange on the coil in order to prevent damaging coil tubing. See  
Figure 6, "PC Series Upflow Coil Installation"  
C
(Min)  
D
Flexible  
Duct Collar  
FURNACE  
Field  
Fabricated  
Ductwork  
WARM AIR PLENUM  
WITH 1” FLANGES  
Do not drill  
or Screw  
this flange  
FIBERGLASS  
INSULATION  
Upflow  
Coil  
Upflow  
Furnace  
FIBERGLASS TAPE  
UNDER FLANGE  
Alternate  
Drain Location  
Primary  
Drain  
Secondary  
Drain  
FIGURE 6: PC Series Upflow Coil Installation  
Table 2: Coil Projection Dimensions - PC Series Coils  
COMBUSTIBLE FLOOR  
BASE ACCESSORY  
COIL SIZE  
DIMENSION “C” INCH  
PC18  
PC24  
3-1/2  
4-1/2  
4-1/2  
5-1/2  
6-1/2  
9
FIGURE 8: Combustible Floor Base Accessory  
RESIDENTIAL AND MODULAR HOME UPFLOW  
RETURN PLENUM CONNECTION  
Return air may enter the furnace through the side(s) or bottom depend-  
ing on the type of application. Return air may not be connected into the  
rear panel of the unit.  
PC30, PC32, PC35  
PC42, PC43, PC36, PC37  
PC48  
PC60  
NOTE: Dimension “C” should be at least 2/3 of dimension “D”. See Fig-  
ure 6, "PC Series Upflow Coil Installation"  
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BOTTOM RETURN AND ATTIC INSTALLATIONS  
Bottom return applications normally pull return air through a base plat-  
form or return air plenum. Be sure the return platform structure or return  
air plenum is suitable to support the weight of the furnace.  
When a furnace is installed in an attic or other insulated space,  
keep all insulating materials at least 12 inches (30.5 cm) away from  
furnace and burner combustion air openings.  
The internal bottom panel must be removed for this application.  
Attic installations must meet all minimum clearances to combustibles  
and have floor support with required service accessibility.  
SUSPENDED FURNACE / CRAWL SPACE  
INSTALLATION  
HORIZONTAL APPLICATION  
The furnace can be hung from floor joists or installed on suitable blocks  
or pad. Blocks or pad installations shall provide adequate height to  
ensure the unit will not be subject to water damage. Units may also be  
suspended from rafters or floor joists using rods, pipe angle supports or  
straps. Angle supports should be placed at the supply air end and near  
the blower deck. Do not support at return air end of unit. All four sus-  
pension points must be level to ensure quite furnace operation. When  
suspending the furnace use a secure platform constructed of plywood  
or other building material secured to the floor joists. Refer to for typical  
crawl space installation.  
FIGURE 9: Horizontal Application  
This furnace may be installed in a horizontal position on either side  
as shown above. It must not be installed on its back.  
ATTIC INSTALLATION  
Support  
Angle Iron  
Bracket  
Bracket  
Line contact only permissible  
between lines formed by the  
intersection of furnace top  
and two sides and building  
joists, studs or framing  
Supply  
Air  
Vent (Maintain  
required  
clearances to  
combustibles)  
Filter rack  
must be a minimum  
distance  
of 18” (45.7 cm)  
from the  
furnace  
6” Min. Between  
Rod & Front of Furnace  
Rod & Back of Furnace  
Sheet metal in  
front of furnace  
combustion air  
Openings is  
1” Max. Between  
Gas Piping  
12”  
FIGURE 11: Typical Suspended Furnace / Crawl Space Installation  
Recommended  
12”  
DOWNFLOW APPLICATION  
30” MIN.  
Work Area  
To apply the furnace in a downflow position, it will be necessary to  
rotate the vent blower 90° left or right so that the vent pipe passes  
through the side of the furnace casing rather than the end. See Figure  
12, "Downflow Venting".  
Return  
Air  
Sediment  
Trap  
FIGURE 10: Typical Attic Installation  
For modulating furnaces to be used in the downflow position, it is  
necessary to rotate the gas valve so that it is upright when the fur-  
nace is installed. Loosen the pipe union between the gas valve and  
manifold, rotate the valve as far upward as it will go, and tighten the  
union. See Figure 13, "Downflow Installation - Gas Valve Rotation".  
This appliance is certified for line contact when the furnace is installed  
in the horizontal left or right position. The line contact is only permissible  
between lines that are formed by the intersection of the top and two  
sides of the furnace and the building joists, studs or framing. This line  
may be in contact with combustible material. Refer to Figure 10, "Typi-  
cal Attic Installation".  
For downflow  
installation,rotate  
gas valve upwards,  
as shown  
Rotate vent  
blower 90°  
either way  
LEFT SIDE VENT  
RIGHT SIDE VENT  
FIGURE 12: Downflow Venting  
FIGURE 13: Downflow Installation - Gas Valve Rotation  
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Vent  
Outlet  
RIGHT SIDE  
FRONT  
LEFT SIDE  
Electrical  
Entry  
Vent Outlet  
Electrical  
Entry  
Gas Pipe  
Entry  
Gas Pipe  
Entry  
33”  
23”  
Thermostat  
Wiring  
Thermostat  
Wiring  
14”  
A
28.5”  
29.5”  
1”  
1.5”  
(For Cladded door add  
appoximately an additional .75”)  
Vent  
Outlet  
.5”  
24.38”  
.5”  
.5”  
B
B
C
.5”  
20”  
24.25”  
SUPPLY END  
RETURN END  
FIGURE 14: Dimensions  
Table 3: Cabinet and Duct Dimensions  
Approximate  
Operating Weights  
Cabinet Dimensions (Inches)  
Nominal  
CFM (m3/min)  
BTUH (kW)  
Input  
Cabinet  
Size  
A
14 1/2  
17 1/2  
21  
A (cm)  
36.8  
44.4  
53.3  
53.3  
53.3  
53.3  
B
13 1/2  
16 1/2  
20  
B (cm)  
34.3  
41.9  
50.8  
50.8  
50.8  
50.8  
C
C (cm)  
26.2  
29.9  
34.5  
34.5  
34.5  
40.1  
Lbs  
94  
60 (17.6)  
80 (23.4)  
80 (23.4)  
100 (29.3)  
100 (29.3)  
120 (35.1)  
1200 (34.0)  
1200 (34.0)  
1600 (45.3)  
1600 (45.3)  
2000 (56.6)  
2000 (56.6)  
A
B
C
C
C
C
10.3  
11.8  
13.6  
13.6  
13.6  
15.8  
103  
114  
118  
122  
129  
21  
20  
21  
20  
21  
20  
SIDE RETURN  
Locate the “L” shaped corner locators. These indicate the size of the cut-  
out to be made in the furnace side panel. Refer to Figure 15, "Side  
Return Cutout Markings".  
SECTION III: FILTERS  
FILTER INSTALLATION  
All applications require the use of a field installed filter. All filters and  
mounting provision must be field supplied.  
Filters must be installed external to the furnace cabinet. DO NOT  
attempt to install filters inside the furnace.  
Front of  
Furnace  
Table 4: Recommended Filter Sizes (High Velocity 600 FPM)  
Side of  
Furnace  
CFM  
(m³/min)  
Cabinet  
Size  
Side  
(in)  
Bottom  
(in)  
1200 (34.0)  
1200 (34.0)  
1600 (45.3)  
2000 (56.6)  
A
B
C
C
16 x 25  
16 x 25  
14 x 25  
16 x 25  
20 x 25  
20 x 25  
Corner  
Markings  
16 x 25  
FIGURE 15: Side Return Cutout Markings  
(2) 16 x 25  
Install the side filter rack following the instructions provided with that  
accessory. If a filter(s) is provided at another location in the return air  
system, the ductwork may be directly attached to the furnace side  
panel.  
NOTES:  
1. Air velocity through throwaway type filters may not exceed 300 feet per  
minute (91.4 m/min). All velocities over this require the use of high velocity  
filters.  
2. Do not exceed 1800 CFM using a single side return and a 16x25 filter. For  
CFM greater than 1800, you may use two side returns or one side and the  
bottom or one side return with a transition to allow use of a 20x25 filter.  
Some accessories such as electronic air cleaners and pleated  
media may require a larger side opening. Follow the instructions  
supplied with that accessory for side opening requirements. Do not  
cut the opening larger than the dimensions shown in Figure 14,  
"Dimensions".  
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HORIZONTAL APPLICATION  
Horizontal Filters  
External Manual  
Shutoff Valve  
To Gas  
Supply  
To Gas  
Supply  
All filters and mounting provision must be field supplied. All installa-  
tions must have a filter installed.  
Any branch duct (rectangular or round duct) attached to the plenum  
must attach to the vertical plenum before the filter. The use of straps  
and / or supports is required to support the weight of the external filter  
box.  
Grounded Joint Union  
may be Installed  
Inside or Outside Unit.  
Drip Leg  
Downflow Filters  
FIGURE 17: Upflow/Downflow Gas Piping  
Downflow furnaces typically are installed with the filters located above  
the furnace, extending into the return air plenum or duct. Any branch  
duct (rectangular or round duct) attached to the plenum must attach to  
the vertical plenum above the filter height.  
Manual  
Shut-off  
Valve  
Filter(s) may be located in the duct system external to the furnace using  
an external duct filter box attached to the furnace plenum or at the end  
of the duct in a return filter grille(s). The use of straps and/or supports is  
required to support the weight of the external filter box.  
Drip  
Leg  
Gas  
Pipe  
Gas Burners  
Gas Valve  
SECTION IV: GAS PIPING  
Gas  
Pipe  
GAS SAFETY  
Drip  
Leg  
Manual  
Shut-off Valve  
An overpressure protection device, such as a pressure regulator,  
must be installed in the gas piping system upstream of the furnace  
and must act to limit the downstream pressure to the gas valve so it  
does not exceed 0.5 PSI (14" w.c. (3.48 kPa). Pressures exceeding  
0.5 PSI (14” w.c. (3.48 kPa) at the gas valve will cause damage to  
the gas valve, resulting in a fire or explosion or cause damage to  
the furnace or some of its components that will result in property  
damage and loss of life.  
FIGURE 18: Horizontal Gas Piping  
An accessible manual shutoff valve must be installed upstream of  
the furnace gas controls and within 6 feet (1.8 m) of the furnace.  
The furnace must be isolated from the gas supply piping system by  
closing its individual external manual shutoff valve during any pressure  
testing of the gas supply piping system at pressures equal to or less  
than 1/2 psig (3.5 kPa).  
Main  
Regulator  
Adjustment  
The gas valve body is a very thin casting that cannot take any  
external pressure. Never apply a pipe wrench to the body of the gas  
valve when installing piping. A wrench must be placed on the octa-  
gon hub located on the gas inlet side of the valve. Placing a wrench  
to the body of the gas valve will damage the valve causing improper  
operation and/or the valve to leak.  
On/Off  
Knob  
Outlet  
Pressure  
Tap  
Inlet  
Pressure  
Tap  
Gas piping may be connected from either side of the furnace using any  
of the gas pipe entry on both sides of the furnace. Refer to Figure 14,  
"Dimensions".  
FIGURE 16: Gas Valve  
GAS CONVERSION FOR PROPANE (LP)  
Plan your gas supply before determining the correct gas pipe entry.  
Use 90-degree service elbow(s), or short nipples and conventional  
90-degree elbow(s) to enter through the cabinet access holes.  
This furnace is constructed at the factory for natural gas-fired operation,  
but may be converted to operate on propane (LP) gas by using a fac-  
tory-supplied LP conversion kit which includes a LP gas valve. Follow  
the instructions supplied with the LP kit.  
GAS PIPING INSTALLATION  
Properly sized wrought iron, approved flexible or steel pipe must be  
used when making gas connections to the unit. If local codes allow the  
use of a flexible gas appliance connection, always use a new listed con-  
nector. Do not use a connector that has previously serviced another gas  
appliance.  
LoNOx furnaces requiring propane (LP) gas must have the LoNOx  
screens removed prior to installation and operation. See propane  
instructions.  
Some utility companies or local codes require pipe sizes larger than the  
minimum sizes listed in these instructions and in the codes. The furnace  
rating plate and the instructions in this section specify the type of gas  
approved for this furnace - only use those approved gases. The instal-  
lation of a drip leg and ground union is required. Refer to Figure 17,  
"Upflow/Downflow Gas Piping".  
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Example – You have a 100,000 BTU/H furnace installed at an elevation  
of 6,000 feet. You clock the gas meter and find that the furnace is actu-  
ally fired at 64,000 BTU/H. Divide 64,000 by 100,000, which gives 0.64  
(64%). The closest number to 64% in the left-hand “Actual Rate” col-  
umn is 65. Read across that row to the column for 6,000 feet elevation,  
which shows “#43”. You should change from the factory #45 orifices to  
larger #43 orifices, which will bring the input rate back up to approxi-  
mately 76,000 BTU/H, which is what it should be for that furnace at  
6,000 feet.  
HIGH ALTITUDE NATURAL GAS ORIFICE  
CONVERSION  
The National Fuel Gas Code requires that gas appliances installed  
above 2,000 feet elevation have their inputs de-rated by 4% per 1,000  
feet above sea level. The modulating furnaces automatically de-rate for  
altitude by measuring the inducer blower pressure and using that to  
determine if there is adequate air to support good combustion. If there  
is not enough combustion air to properly support 100% of the furnace  
nameplate input rate, the control will reduce the input to the point that  
there will be good combustion.  
Table 5: High Altitude Orifices  
The factory gas orifice sizes are based on a gas heating value of  
1030 BTU/Cu.ft., so if your gas value is significantly higher or  
lower than that, it may be necessary to change to smaller or larger  
gas orifices.  
Elevation in Feet Above Sea Level  
Actual Rate  
(percent of  
nameplate)  
4,000 5,000 6,000 7,000 8,000 9,000 10,000  
84% 80% 76% 72% 68% 64%  
Orifice Drill Size  
60%  
The chart below shows recommended gas orifice sizes to use at vari-  
ous altitudes and at various de-ration levels. To use the chart, follow  
these instructions:  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
48  
47  
46  
45  
45  
44  
43  
42  
41  
40  
39  
49  
48  
47  
46  
45  
45  
44  
43  
42  
41  
40  
49  
49  
48  
47  
46  
45  
44  
43  
42  
41  
40  
50  
50  
49  
48  
47  
45  
45  
44  
43  
32  
40  
51  
50  
49  
49  
48  
47  
45  
45  
44  
43  
43  
51  
50  
49  
49  
48  
47  
45  
45  
45  
43  
42  
52  
51  
50  
50  
49  
49  
48  
47  
46  
44  
42  
1. Clock the gas meter and calculate the actual input rate using your  
local gas heating value. See "CALCULATING THE FURNACE  
INPUT (NATURAL GAS)" in this manual.  
2. Divide that input rate by the input rate shown on the furnace rating  
plate to get the actual de-ration percent.  
3. Read down the left-hand “Actual Rate” column to find the closest  
number to your actual de-ration percent.  
4. Read across that row to the column for the elevation at your loca-  
tion. The number listed there is the orifice size that is proper for  
your unit.  
PROPANE KITS  
It is very important to choose the correct kit and/or gas orifices for the altitude and the type of gas for which the furnace is being installed.  
Only use natural gas in furnaces designed for natural gas. Only use propane (LP) gas for furnaces that have been properly converted to use pro-  
pane (LP) gas. Do not use this furnace with butane gas.  
Incorrect gas orifices or a furnace that has been improperly converted will create an extremely dangerous condition resulting in premature heat  
exchanger failure, excessive sooting, high levels of carbon monoxide, personal injury, property damage, a fire hazard and/or death.  
Propane (LP) conversions are required in order for the appliance to satisfactory meet the application.  
An authorized distributor or dealer must make all gas conversions.  
In Canada, a certified conversion station or other qualified agency, using factory specified and/or approved parts, must perform the conversion.  
The installer must take every precaution to insure that the furnace has been converted to the proper gas orifice size when the furnace is installed.  
Do not attempt to drill out any orifices to obtain the proper orifice size. Drilling out a gas orifice will cause misalignment of the burner flames,  
causing premature heat exchanger burnout, high levels of carbon monoxide, excessive sooting, a fire hazard, personal injury, property damage  
and/or death.  
SECTION V: ELECTRICAL POWER  
ELECTRICAL POWER CONNECTIONS  
Use copper conductors only.  
Field wiring to the unit must be grounded. Electric wires that are field  
installed shall conform to the temperature limitation for 63°F (35°C) rise  
wire when installed in accordance with instructions. Refer to Table 6,  
"Ratings & Physical / Electrical Data" in these instructions for specific  
furnace electrical data.  
Table 6: Ratings & Physical / Electrical Data  
Input  
Max/Min  
Output  
Max/Min  
Nominal  
Airflow  
Air Temp. Rise Air Temp. Rise  
Max Input Min Input  
Max. Outlet  
Air Temp  
Max  
Min. wire Size  
Total Unit  
Amps  
AFUE  
Over-Current (awg) @ 75 ft  
m3/min  
Protect  
one way  
MBH  
kW  
MBH  
kW  
CFM  
°F °C °F °C  
°F  
°C  
60/30 17.6/8.8 48/24 14.1/7.0 1200 34.0  
80/40 23.5/11.8 64/32 18.8/9.4 1200 34.0  
80/40 23.5/11.8 64/32 18.8/9.4 1600 45.3  
100/50 29.3/14.7 80/40 23.4/11.7 1600 45.3  
100/50 29.3/14.7 80/40 23.4/11.7 2000 56.6  
120/60 33.7/16.9 96/48 28.1/14.1 2000 56.6  
7.0  
7.5  
80.0 35-65 19-36 20-50 11-28  
80.0 40-70 22-39 20-50 11-28  
80.0 40-70 22-39 20-50 11-28  
80.0 40-70 22-39 20-50 11-28  
80.0 35-65 19-36 20-50 11-28  
80.0 45-75 25-42 25-55 13-31  
15  
15  
15  
15  
20  
20  
14  
14  
14  
14  
12  
12  
165 73.9  
170 76.7  
170 76.7  
170 76.7  
165 73.9  
175 79.4  
10.0  
10.0  
17.0  
17.0  
Annual Fuel Utilization Efficiency (AFUE) numbers are determined in accordance with DOE Test procedures.  
Wire size and over current protection must comply with the National Electrical Code (NFPA-70-latest edition) and all local codes.  
10  
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SUPPLY VOLTAGE CONNECTIONS  
LOW VOLTAGE CONTROL WIRING CONNECTIONS  
Install the field-supplied thermostat by following the instructions that  
come with the thermostat. With the thermostat set in the OFF position  
and the main electrical source disconnected, connect the thermostat  
wiring from the wiring connections on the thermostat to the terminal  
board on the ignition module, as shown in Figures 20-25, Thermostat  
Charts. Electronic thermostats may require the common wire to be con-  
nected as shown in Figure 16, "Gas Valve". Apply strain relief to ther-  
mostat wires passing through cabinet.  
Junction  
Box  
Connect ground  
lead to screw  
Electrical Entry  
BLK  
L1-Hot  
WHT  
Neutral  
Set the heat anticipator in the room thermostat to 0.4 amps. Setting  
it lower will cause short cycles. Setting it higher will cause the room  
temperature to exceed the set points.  
FIGURE 19: Electrical Wiring  
1. Provide a power supply separate from all other circuits. Install  
overcurrent protection and disconnect switch per local/national  
electrical codes. The switch should be close to the unit for conve-  
nience in servicing. With the disconnect or fused switch in the OFF  
position, check all wiring against the unit wiring label. Refer to the  
wiring diagram in this instruction.  
Some electronic thermostats do not have adjustable heat anticipa-  
tors. They should be set to six cycles per hour. Follow the thermo-  
stat manufacturer's instructions.  
The 24-volt, 40 VA transformer is sized for the furnace components  
only, and should not be connected to power auxiliary devices such as  
humidifiers, air cleaners, etc. The transformer may provide power for an  
air conditioning unit contactor.  
2. Remove the screws retaining the wiring box cover. Route the  
power wiring through the opening in the unit into the junction box  
with a conduit connector or other proper connection. In the junc-  
tion box there will be 3 wires, a Black Wire, a White Wire. Connect  
the power supply as shown on the unit-wiring label on the inside of  
the blower compartment door or the wiring schematic in this sec-  
tion. The black furnace lead must be connected to the L1 (hot)  
wire from the power supply. The white furnace screw must be con-  
nected to neutral. Connect the power supply ground to the green  
screw (equipment ground) An alternate wiring method is to use a  
field provided 2” (5.1 cm) x 4” (10.2 cm) box and cover on the out-  
side of the furnace. Route the furnace leads into the box using a  
protective bushing where the wires pass through the furnace  
panel. After making the wiring connections replace the wiring box  
cover and screws. Refer to Figure 19, "Electrical Wiring".  
AIR CONDITIONER CONNECTIONS  
This furnace may be used with single-stage or two-stage air condition-  
ing units.  
For Single-Stage A/C - Connect the low voltage wiring as shown in  
Figures 20, Thermostat Chart.  
For Two-Stage A/C - Use a two-stage thermostat, connect the low volt-  
age wiring as shown in Figures 21, Thermostat Chart.  
For Two-Stage A/C using a Single-Stage Thermostat - connect the  
low voltage wiring as shown in Figures 21, Thermostat Chart.  
This furnace control board can control a two-stage A/C using only a sin-  
gle-stage thermostat. In this case, the furnace control switches between  
high cool and low cool based on the calculated cooling load.  
3. The furnace's control system requires correct polarity of the power  
supply and a proper ground connection. Refer to Figure 19, "Elec-  
trical Wiring"  
ZONING OPERATION  
This furnace may be used in zoning systems, using a separate after-  
market zoning control. For use in zoned systems, put the ZONE CON-  
TROL jumper on the furnace control board in the “YES” position.  
The power connection leads and wiring box may be relocated to the  
left side of the furnace. Remove the screws and cut wire tie holding  
excess wiring. Reposition on the left side of the furnace and fasten  
using holes provided.  
HEAT PUMP OPERATION  
This furnace may be used in conjunction with a heat pump in dual fuel  
applications. For heat pump applications, put the HEAT PUMP jumper  
on the furnace control board in the “YES” position. Connect the low volt-  
age wiring as shown in Figures 20-25, Thermostat Charts. If a two-  
stage heat pump is to be used, a two-stage thermostat is required.  
Johnson Controls Unitary Products  
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Product Catalog Section.  
ID MODELS  
TM(8,L)M  
YM(8,L)M  
CM(8,L)M  
THERMOSTAT  
LM(8,L)M  
SINGLE STAGE  
MODULATING  
FURNACE  
AIR  
*PP11C70224  
CONDITIONER  
MODULATING  
1
FURNACE CONTROL  
C
C
24 – Volt Common  
24 – Volt Common  
Y1  
Single  
Stage Compressor  
Y
Y  
Full Stage Compressor  
CompressorContactor  
RH  
R
24 – Volt Hot  
(Heat XFMR)  
24 – Volt Hot  
G
G
Fan  
Fan  
W
Modulating Heat  
RC  
Y/Y2  
24 – Volt Hot  
(Cool XFMR)  
Second or Full  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
LO COMP  
Single Stage  
Compressor (OUT)  
HI COMP  
Second Stage  
Compressor (OUT)  
W
Full Stage Heat  
DHUM  
Dehumidification-  
Open on Humidity Rise  
HM1  
Humidistat  
External Humidistat  
(Optional)  
2
Open on Humidity Rise  
Clipping Jumper W914 for  
electric heat on thermostat  
is not necessary  
Move HUMIDISTAT  
jumper to “YES”  
if humidistat is to be used.  
2
Part Number:  
Part Numbers:  
1
S1-2HU16700124  
SAP  
=
Legacy  
FIGURE 20: Thermostat Chart - Single Stage Air Conditioner – Variable Speed or PSC Modulating Furnace  
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368261-UIM-A-0508  
ID MODELS  
TM(8,L)M  
YM(8,L)M  
CM(8,L)M  
LM(8,L)M  
THERMOSTAT  
*DN22U00124  
THERMOSTAT  
*PP32U70124  
TWO STAGE  
AIR  
CONDITIONER  
MODULATING  
FURNACE  
MODULATING  
1
FURNACE CONTROL  
C
C
C
C
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
Y1  
Single  
Stage Compressor  
Y1  
Y1  
Y1  
First Stage Compressor  
First Stage Compressor  
First Stage Compressor  
R
R
R
R
24 – Volt Hot  
(Heat XFMR)  
24 – Volt Hot  
(Heat XFMR)  
24 – Volt Hot  
24 – Volt Hot  
G
G
G
Fan  
Fan  
Fan  
E/W1  
E/W1  
W
First Stage Heat  
Emergency Heat  
Modulating Heat  
W2  
AUX  
Second Stage Heat  
Auxiliary Heat  
R
R
Y/Y2  
24 – Volt Hot  
(Cool XFMR)  
24 – Volt Hot  
(Cool XFMR)  
Second or Full  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
LO COMP  
Single Stage  
Compressor (OUT)  
HI COMP  
Y2  
Y2  
Y2  
Second Stage  
Compressor  
Second Stage  
Compressor  
Second Stage  
Compressor (OUT)  
Second Stage  
Compressor  
DHUM  
Dehumidification-  
Open on Humidity Rise  
External Humidistat  
(Optional)  
2
Open on Humidity Rise  
Move HUMIDISTAT  
jumper to “YES”  
if humidistat is to be used.  
Connection of the “C”  
terminal, 24-volt common terminal, 24-Volt common  
is optional when used with is optional when used with  
Connection of the “C”  
batteries  
Thermostat Installer Setup Thermostat Installer Setup  
1-System Type-must  
0170-System Type-must  
batteries  
be set to 6-2 Heat/2 Cool be set to 8-2 Heat/2 Cool  
Multistage Conventional Multistage Conventional  
Thermostat Installer Setup  
15-Compressor Protection  
-must be set to 5  
Part Numbers:  
1
2
Part Number:  
S1-2HU16700124  
SAP  
=
Legacy  
FIGURE 21: Thermostat Chart - Two Stage Air Conditioner – Variable Speed or PSC Modulating Furnace  
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ID MODELS  
TM(8,L)M  
YM(8,L)M  
CM(8,L)M  
LM(8,L)M  
THERMOSTAT  
TWO STAGE  
AIR  
CONDITIONER  
MODULATING  
FURNACE  
*PP11C70224  
MODULATING  
1
FURNACE CONTROL  
C
C
24 – Volt Common  
24 – Volt Common  
Y1  
Single  
Stage Compressor  
Y
Y1  
Full Stage Compressor  
First Stage Compressor  
RH  
R
R
24 – Volt Hot  
(Heat XFMR)  
24 – Volt Hot  
24 – Volt Hot  
G
G
Fan  
Fan  
W
Modulating Heat  
RC  
Y/Y2  
24 – Volt Hot  
(Cool XFMR)  
Second or Full  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
LO COMP  
Single Stage  
Compressor (OUT)  
HI COMP  
Y2  
Second Stage  
Compressor (OUT)  
Second Stage  
Compressor  
W
Full Stage Heat  
DHUM  
Dehumidification-  
Open on Humidity Rise  
HM1  
Humidistat  
External Humidistat  
(Optional)  
2
Open on Humidity Rise  
Clipping Jumper W914 for  
electric heat on thermostat  
is not necessary  
Move HUMIDISTAT  
jumper to “YES”  
if humidistat is to be used.  
2
Part Number:  
Part Numbers:  
1
S1-2HU16700124  
SAP  
=
Legacy  
FIGURE 22: Thermostat Chart - Two Stage Air Conditioner with Single Stage Thermostat – Variable Speed or PSC Modulating Furnace  
14  
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ID MODELS  
OD MODELS  
E*R*  
*RHS  
TM(8,L)M  
E*ZD  
E*B*  
HP*  
YM(8,L)M  
CM(8,L)M  
LM(8,L)M  
*HGD  
THERMOSTAT  
THERMOSTAT  
THERMOSTAT  
*BP21H50124  
*BN21H00124  
*DP21H40124  
*DN21H00124  
MODULATING  
FURNACE  
SINGLE STAGE  
HEAT PUMP  
*DP32H70124  
*DN22U00124  
MODULATING  
FURNACE CONTROL  
DEMAND DEFROST  
CONTROL  
2
1
C
C
C
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
Y1  
Single  
Stage Compressor  
Y1  
Y
First Stage Compressor  
Compressor  
R
R
R
24 – Volt Hot  
24 – Volt Hot  
24 – Volt Hot  
G
G
Fan  
Fan  
E
W
W1/66(out)  
Heat  
Emergency Heat  
Modulating Heat  
W2  
N/A  
N/A  
Third Stage Heat  
Y/Y2  
Second or Full  
Stage Compressor  
O
O
O
Reversing Valve  
Energized in Cool  
Reversing Valve  
Energized in Cool  
LO COMP  
Single Stage  
Compressor (OUT)  
HI COMP  
Reversing Valve  
Energized in Cool  
L
X/L  
Malfunction Light  
Malfunction Light  
Y2  
Second Stage  
Compressor (OUT)  
Second Stage Compressor  
W1  
W
Second Stage Aux. Heat  
Auxiliary Heat  
DHUM  
Dehumidification-  
Open on Humidity Rise  
External Humidistat  
(Optional)  
3
Open on Humidity Rise  
Move HUMIDISTAT  
jumper to “YES”  
if humidistat is to be used.  
Step 1 of Thermostat  
Installer / Configuration  
Menu must be set to  
Heat Pump 1  
Step 9 of Thermostat  
Installer / Configuration  
Menu must be set to  
Pump OFF  
Part Numbers:  
3
Part Numbers:  
1
Part Number:  
S1-2HU16700124  
2
SAP  
=
Legacy  
SAP  
=
Legacy  
67297 = 031-01975  
FIGURE 23: Thermostat Chart - Single Stage Heat Pump – Variable Speed or PSC Modulating Furnace  
Johnson Controls Unitary Products  
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ID MODELS  
OD MODELS  
YZB  
TM(8,L)M  
YMB  
H*3  
YM(8,L)M  
CM(8,L)M  
LM(8,L)M  
THERMOSTAT  
THERMOSTAT  
THERMOSTAT  
*BP21H50124  
*BN21H00124  
*DP21H40124  
*DN21H00124  
MODULATING  
FURNACE  
SINGLE STAGE  
HEAT PUMP  
*DN22U00124  
*DP32H70124  
YORKGUARD VI  
CONTROL  
MODULATING  
FURNACE CONTROL  
2
1
C
C
C
C
C
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
Y1  
Single  
Stage Compressor  
Y1  
Single  
Stage Compressor  
Y1  
Y1  
Y1  
First Stage Compressor  
First Stage Compressor First Stage Compressor  
R
R
R
R
R
24 – Volt Hot  
(Heat XFMR)  
24 – Volt Hot  
24 – Volt Hot  
24 – Volt Hot  
24 – Volt Hot  
G
G
G
G
Fan  
Fan  
Fan  
Fan  
E
E
E
W
W1 OUT  
Emergency Heat  
Emergency Heat  
Emergency Heat  
Modulating Heat  
First Stage Heat  
W2  
W2 OUT  
Third Stage Heat  
Second Stage Heat  
R
Y/Y2  
Y2 OUT  
Second  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
24 – Volt Hot  
(Cool XFMR)  
Second or Full  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
LO COMP  
Single Stage  
Compressor (OUT)  
HI COMP  
O
O
O/B  
Reversing Valve  
Energized in Cool  
Reversing Valve  
Energized in Cool  
Reversing Valve  
L
L
L
X/L  
Malfunction Light  
Malfunction Light  
Malfunction Light  
Malfunction Light  
Y2  
Y2  
Y2  
Y2  
Second  
Stage Compressor  
Second  
Stage Compressor  
Second  
Stage Compressor  
Second Stage  
Compressor (OUT)  
Second  
Stage Compressor  
AUX  
W2  
W1  
W
Auxiliary Heat  
Second Stage Heat  
Second Stage Aux. Heat  
Auxiliary Heat  
DHUM  
Dehumidification-  
Open on Humidity Rise  
BSG  
Bonnet Sensor  
Bonnet Sensor  
(Optional)  
External Humidistat  
(Optional)  
Open on Humidity Rise  
3
BS  
Bonnet Sensor  
Step 1 of Thermostat  
Installer / Configuration  
Menu must be set to  
Heat Pump 1  
Thermostat Installer Setup  
1-System Type-must be set  
to 5 – 2 Heat/1 Heat Pump  
Move HUMIDISTAT  
jumper to “YES”  
if humidistat is to be used.  
Change FFuel jumper  
on the heat pump control  
to “ON”  
Change Hot Heat Pump  
jumper on the heat  
pump control to “ON” if  
Hot Heat Pump  
B/O Switch on Thermostat  
must be in the O position  
Thermostat Installer Setup  
2-Changeover Valve-must  
be set to 0 – O/B terminal  
Energized in Cooling  
Operation is desired.  
Part Numbers:  
3
Part Number:  
S1-2HU16700124  
Part Numbers:  
2
1
SAP  
=
Legacy  
SAP  
=
Legacy  
126768 = 031-09137  
18395 = 031-01996  
340512 = 031-09178  
FIGURE 24: Thermostat Chart - Single Stage Heat Pump – Variable Speed or PSC Modulating Furnace  
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ID MODELS  
OD MODELS  
YZE  
TM(8,L)M  
YZH  
H*5  
H*8  
YM(8,L)M  
CM(8,L)M  
LM(8,L)M  
THERMOSTAT  
THERMOSTAT  
*DN22H00124  
*DP22U70124  
MODULATING  
FURNACE  
TWO STAGE  
HEAT PUMP  
*PP32U70124  
YORKGUARD VI  
CONTROL  
MODULATING  
FURNACE CONTROL  
2
1
C
C
C
C
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
24 – Volt Common  
Y1  
Single  
Stage Compressor  
Y1  
Single  
Stage Compressor  
Y
Y1  
First Stage Compressor First Stage Compressor  
R
R
R
R
24 – Volt Hot  
24 – Volt Hot  
(Heat XFMR)  
24 – Volt Hot  
24 – Volt Hot  
G
G
G
Fan  
Fan  
Fan  
E
W
W1 OUT  
Emergency Heat  
Modulating Heat  
First Stage Heat  
W2  
W2 OUT  
Second Stage Aux. Heat  
Second Stage Heat  
RC  
Y/Y2  
Y2 OUT  
Second  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
24 – Volt Hot  
(Cool XFMR)  
Second or Full  
Stage Compressor  
O
Reversing Valve  
Energized in Cool  
LO COMP  
Single Stage  
Compressor (OUT)  
HI COMP  
O
O/B  
Reversing Valve  
Energized in Cool  
Reversing Valve  
L
L
X/L  
Malfunction Light  
Malfunction Light  
Malfunction Light  
Y2  
Y2  
Y2  
Second  
Stage Compressor  
Second  
Stage Compressor  
Second Stage  
Compressor (OUT)  
Second  
Stage Compressor  
AUX  
E/W1  
W
Auxiliary Heat  
First Stage Aux. Heat  
Auxiliary Heat  
DHUM  
Dehumidification-  
Open on Humidity Rise  
BSG  
Bonnet Sensor  
Bonnet Sensor  
(Optional)  
External Humidistat  
(Optional)  
3
BS  
Open on Humidity Rise  
Bonnet Sensor  
Thermostat Installer Setup  
0170-System Type-  
must be set to 12  
3 Heat/2 Heat Pump  
Thermostat Installer Setup  
0190-Changeover Valve-  
must be set to 0  
Step 1 of Thermostat  
Installer/Configuration  
Menu must be set to “HP2”  
Selection of GAS/ELEC  
switch on thermostat  
not necessary  
Move HUMIDISTAT  
jumper to “YES”  
if humidistat is to be used.  
Change FFuel jumper  
on the heat pump control  
to “ON”  
Change Hot Heat Pump  
jumper on the heat  
pump control to “ON” if  
Hot Heat Pump  
O/B terminal  
Operation is desired.  
Energized in Cooling  
Thermostat Installer Setup  
0200-Backup Heat Source-  
must be set to 1  
Heat Pump Backup Heat  
Source is Fossil Fuel  
Thermostat Installer Setup  
0210-External Fossil Fuel  
Kit- must be set to 1  
Heat Pump Control  
Part Numbers:  
Part Numbers:  
2
1
SAP  
=
Legacy  
SAP  
=
Legacy  
126768 = 031-09137  
18395 = 031-01996  
340512 = 031-09178  
is Controlling Heat Pump  
Backup Heat  
FIGURE 25: Thermostat Chart - Two Stage Heat Pump – Variable Speed or PSC Modulating Furnace  
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The furnace shall be connected to a type B vent connector, and  
shall be connected to a type B vent only. The furnace shall not be  
ACCESSORY CONNECTIONS  
The furnace control will allow power-switching control of various acces-  
sories.  
connected to  
a
chimney flue serving  
a
separate appliance  
designed to burn solid fuel. Single-wall vent pipe is not allowed.  
ELECTRONIC AIR CLEANER CONNECTION  
It is recommended that the appliance is installed in a location where the  
space temperature is 32 °F (0°C) or higher. If the appliance is installed  
in a location where the ambient temperature is below 32 °F (0°C), the  
combustion byproducts could condense causing damage to the appli-  
ance heat exchanger.  
Two 1/4” (0.64 cm) spade terminals (EAC and NEUTRAL) for electronic  
air cleaner connections are located on the control board. The terminals  
provide 115 VAC (1.0 amp maximum) during circulating blower opera-  
tion.  
This appliance may be common vented with another gas appliance for  
residential installations as allowed by the codes and standards listed in  
these instructions.  
HUMIDIFIER CONNECTION  
Two 1/4” (0.64 cm) spade terminals (HUM and NEUTRAL) for humidi-  
fier connections are located on the control board. The terminals provide  
115 VAC (1.0 amp maximum) during heating system operation.  
VENTING  
A mounting hole is provided on the control panel next to the furnace  
control board for mounting a humidifier transformer if required.  
Category I venting consists of vertically venting one or more appliances  
in B-vent or B-vent connectors. Type B-vent system extends in a gen-  
eral vertical direction and does not contain offsets exceeding 45°. A  
vent system having not more than one 60° offset is permitted.  
HUMIDISTAT CONNECTION  
For better humidity control during cooling operation, an external humi-  
distat may be used. When using a external humidistat, put the HUMI-  
DISTAT jumper in the “YES” position. Connect the low voltage wiring as  
shown in Figures 20-25, Thermostat Charts.  
VENTING INTO AN EXISTING CHIMNEY  
This furnace may not be connected to any masonry chimney. However,  
an existing masonry chimney may be used on as a chase through  
which the metal vent pipe passes.  
SECTION VI: TWINNING AND STAGING  
FAN-ASSISTED COMBUSTION SYSTEM  
Twinning and staging is NOT allowed for modulating furnaces.  
This appliance is equipped with an integral mechanical means to draw  
products of combustion through the heat exchanger.  
SECTION VII: VENT SYSTEM  
Ambient Combustion Air Supply  
VENT CONNECTIONS  
This type installation will draw the air required for combustion from  
within the space surrounding the appliance and from areas or rooms  
adjacent to the space surrounding the appliance. This may be from  
within the space in a non-confined location or it may be brought into the  
furnace area from outdoors through permanent openings or ducts. A  
single, properly sized pipe from the furnace vent connector to the out-  
doors must be provided. For upflow models combustion air is brought  
into the furnace through the unit top panel opening.  
Figure 26, "Combustion Air Inducer" shows the furnace as it is shipped  
from the factory. To convert to a horizontal or downflow position, remove  
the four screws that secure the inducer assembly and rotate 90° being  
careful not to damage the gasket. Reinstall screws. Remove cap from  
appropriate vent outlet location on the cabinet cut insulation in cabinet  
to same size as the hole provided and reinstall cap in the hole in the top  
panel.  
COMBUSTION  
AIR  
In downflow applications, do not block the combustion air inlet. The  
furnace must be installed on a coil cabinet or subbase to allow com-  
bustionair to enter the burner compartment.  
COMBUSTION AIR INDUCER  
90°  
Mounting Screw  
(Remove)  
90°  
FIGURE 27: Combustion Airflow Path Through The Furnace Casing to  
Flue Transition  
(Do Not Remove)  
Pressure Switch  
Tube Routing  
the Burner Compartment  
Pressure  
Switch  
This type of installation requires that the supply air to the appli-  
ance(s) be of a sufficient amount to support all of the appliance(s)  
in the area. Operation of a mechanical exhaust, such as an exhaust  
fan, kitchen ventilation system, clothes dryer or fireplace may cre-  
ate conditions requiring special attention to avoid unsatisfactory  
operation of gas appliances. A venting problem or a lack of supply  
air will result in a hazardous condition, which can cause the appli-  
ance to soot and generate dangerous levels of CARBON MONOX-  
IDE, which can lead to serious injury, property damage and / or  
death.  
Mounting Screw  
(Remove)  
FIGURE 26: Combustion Air Inducer  
CATEGORY 1 - 450 F. MAX. VENT TEMP.  
The venting system must be installed in accordance with Section 5.3,  
Air for Combustion and Ventilation, of the National Fuel Gas Code  
Z223.1/NFPA 54 (latest edition), or Sections 7.2, 7.3 or 7.4 of CSA  
B149.1, National Gas and Propane Codes (latest edition) or applicable  
provisions of the local building code and these instructions.  
18  
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An unconfined space is not less than 50 cu.ft (1.42 m3) per 1,000 Btu/  
hr (0.2928 kW) input rating for all of the appliances installed in that  
area.  
When a Category I furnace is removed or replaced, the original  
venting system may no longer be correctly sized to properly vent  
the attached appliances.  
Rooms communicating directly with the space containing the appli-  
ances are considered part of the unconfined space, if openings are fur-  
nished with openings or louvers.  
An improperly sized vent system can cause CARBON MONOXIDE  
to spill into the living space causing personal injury, and or death.  
A confined space is an area with less than 50 cu.ft (1.42 m3) per 1,000  
Btu/hr (0.2928 kW) input rating for all of the appliances installed in that  
area. The following must be considered to obtain proper air for combus-  
tion and ventilation in confined spaces.  
Table 8: Unconfined Space Minimum Area in Square Inch  
Minimum Free Area in Square Feet  
BTUH Input Rating  
Combustion Air Source From Outdoors  
Required for Each Opening  
60 (387 cm2)  
The blocking effects of louvers, grilles and screens must be given con-  
sideration in calculating free area. If the free area of a specific louver or  
grille is not known, refer to Table 7, to estimate free area.  
60,000  
80 (516 cm2)  
80,000  
100 (645 cm2)  
100,000  
Table 7: Estimated Free Area  
120 (742 cm2)  
120,000  
Wood or Metal  
Louvers or Grilles  
Wood 20-25%*  
Metal 60-70% *  
Table 9: Free Area  
1/4” (0.635 cm)  
mesh or larger 100%  
Minimum Free Area Required for Each Opening  
Screens+  
BTUH Input  
Rating  
Vertical Duct or  
Opening to Outside  
(4,000 BTUH)  
Horizontal Duct  
(2,000 BTUH)  
Round Duct  
(4,000 BTUH)  
* Do not use less than 1/4”(0.635 cm) mesh  
+ Free area of louvers and grille varies widely; the installer should follow  
louver or grille manufacturer’s instructions.  
30 in2 (193 cm2)  
40 in2 (258 cm2)  
50 in2 (322 cm2)  
60 in2 (387 cm2)  
15 in2 (97 cm2)  
20 in2 (129 cm2)  
25 in2 (161 cm2)  
30 in2 (193 cm2)  
60,000  
80,000  
5” (13 cm)  
5” (13 cm)  
6” (15 cm)  
7” (18 cm)  
Dampers, Louvers and Grilles (Canada Only)  
1. The free area of a supply air opening shall be calculated by sub-  
tracting the blockage area of all fixed louvers grilles or screens  
from the gross area of the opening.  
100,000  
120,000  
2. Apertures in a fixed louver, a grille, or screen shall have no dimen-  
sion smaller than 0.25” (0.64 cm).  
EXAMPLE: Determining Free Area.  
Appliance 1 Appliance  
2 Total Input  
3. A manually operated damper or manually adjustable louvers are  
not permitted for use.  
100,000 + 30,000 = (130,000 ÷ 4,000) = 32.5 Sq. In. Vertical  
Appliance 1 Appliance 2 Total Input  
100,000 + 30,000 = (130,000 ÷ 2,000) = 65 Sq. In. Horizontal  
4. A automatically operated damper or automatically adjustable lou-  
vers shall be interlocked so that the main burner cannot operate  
unless either the damper or the louver is in the fully open position.  
Gas  
Vent  
Gas  
Vent  
Gas  
Vent  
Gable  
Vent  
Gable  
Vent  
Ventilated  
Attic  
Ventilated  
Attic  
Optional  
Inlet (a)  
Top Above  
Insulation  
Top Above  
Insulation  
Outlet  
Air (a)  
Soffit  
Vent  
Soffit  
Vent  
Outlet  
Air (b)  
Outlet  
Air (a)  
Gas  
Water  
Heater  
Gas  
Water  
Heater  
Gas  
Water  
Heater  
Inlet  
Air (b)  
Inlet  
Air (b)  
Inlet  
Air (a)  
Inlet  
Air (a)  
Ventilated  
Crawl Space  
FIGURE 28: Outside and Ambient Combustion Air  
5. A square or rectangular shaped duct shall only be used when the  
Air Supply Openings and Ducts  
required free area of the supply opening is 9 in2 (58.06 cm2) or  
larger. When a square or rectangular duct is used, its small dimen-  
sionshall not be less than 3 in (7.6 cm).  
1. An opening may be used in lieu of a duct to provide to provide the  
outside air supply to an appliance unless otherwise permitted by  
the authority having jurisdiction. The opening shall be located  
within 12” (30.5 cm) horizontally from, the burner level of the appli-  
ance. Refer to “COMBUSTION AIR SOURCE FROM OUTDOORS  
and VENT AND SUPPLY AIR SAFETY CHECK” in these instruc-  
tions for additional information and safety check procedure.  
6. An air inlet supply from outdoors shall be equipped with a means  
to prevent the direct entry of rain and wind. Such means shall not  
reduce the required free area of the air supply opening.  
7. An air supply inlet opening from the outdoors shall be located not  
less than 12” (30.5 cm) above the outside grade level.  
2. The duct shall be either metal, or a material meeting the class 1  
requirements of CAN4-S110 Standard for Air Ducts.  
Combustion Air Source from Outdoors  
3. The duct shall be least the same cross-sectional area as the free  
area of the air supply inlet opening to which it connects.  
1. Two permanent openings, one within 12 in (30.5 mm) of the top  
and one within 12 in (30.5 mm) of bottom of the confined space,  
Two permanent openings, shall communicate directly or by means  
of ducts with the outdoors, crawl spaces or attic spaces.  
4. The duct shall terminate within 12 in (30.5 cm) above, and within  
24 in (61 cm) horizontally from, the burner level of the appliance  
having the largest input.  
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2. One permanent openings, commencing within 12 in (30.5 mm)of  
the top of the enclosure shall be permitted where the equipment  
has clearances of at least 1 in (2.54 cm) from the sides and back  
and 6 in (15.24 cm) from the front of the appliance. The opening  
shall communicate directly with the outdoors and shall have a min-  
imum free area of:  
Vent and Supply (Outside) Air Safety Check Procedure  
For Category I furnaces, vent installations shall be in accordance with  
Parts 7 and 11 of the National Fuel Gas Code, ANSI Z223.1/NFPA 54,  
and or Section 7 and Appendix B of the CSA B149.1, Natural Gas and  
Propane Installation Codes, the local building codes, furnace and vent  
manufacture's instructions.  
a. 1 square in per 3000 Btu per hour (6.45 cm3 per 0.879 kW) of  
the total input rating of all equipment located in the enclosure.  
Multi-story or common venting systems are permitted and must be  
installed in accordance with the National Fuel Gas Code, ANSI Z223.1/  
NFPA 54 and / or the CSA B149.1, Natural Gas and Propane Installa-  
tion Codes, local codes, and the manufacture's instructions.  
b. Not less than the sum of all vent connectors in the confined  
space.  
3. The duct shall be least the same cross-sectional area as the free  
area of the air supply inlet opening to which it connects.  
Vent connectors serving Category I furnaces shall not be connected  
into any portion of mechanical draft systems operating under positive  
pressure.  
4. The blocking effects of louvers, grilles and screens must be given  
consideration in calculating free area. If the free area of a specific  
louver or a grille is not known. Refer to Table 7, "Estimated Free  
Area" to estimate free area.  
Horizontal portions of the venting system shall be supported to prevent  
sagging using hangers or perforated straps and must slope upwards  
not less than 1/4" per foot (0.635 cm/m) from the furnace to the vent ter-  
minal.  
Ventilated Combustion Air  
The ventilated attic space or a crawl space from which the combustion  
air is taken must comply with the requirements specified in “AIR  
SOURCE FROM OUTDOORS” in this instruction or in Section 5.3, Air  
for Combustion and Ventilation of the National Fuel Gas Code, ANSI  
Z223.1 (latest edition). This type installation requires two properly sized  
pipes. One brings combustion air from a properly ventilated attic space  
or crawl space and a second pipe that extends from the furnace vent  
connection (top right of unit) to the exterior of the building.  
It is recommended that you follow the venting safety procedure below.  
This procedure is designed to detect an inadequate ventilation system  
that can cause the appliances in the area to operate improperly causing  
unsafe levels of Carbon Monoxide or an unsafe condition to occur.  
CARBON MONOXIDE POISONING HAZARD  
Failure to follow the steps outlined below for each appliance connected to the venting system being placed into operation could result in carbon-  
monxide poisoning or death.  
The following steps shall be followed for each appliance connected to the venting system being placed into operation, while all other appliances  
connected to the venting system are not in operation:  
1. Inspect the venting system for proper size and horizontal pitch. Determine that there is no blockage, restriction, leakage, corrosion or other  
deficiencies, which could cause an unsafe condition  
2. Close all building doors and windows and all doors.  
3. Turn on clothes dryers and TURN ON any exhaust fans, such as range hoods and bathroom exhausts, so they shall operate at maximum  
speed. Open the fireplace dampers. Do not operate a summer exhaust fan.  
4. Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so the appliance shall operate contin-  
uously.  
5. Test each appliance (such as a water heater) equipped with a draft hood for spillage (down-draft or no draft) at the draft hood relief opening  
after 5 minutes of main burner operation. Appliances that do not have draft hoods need to be checked at the vent pipe as close to the  
appliance as possible. Use a combustion analyzer to check the CO2 and CO levels of each appliance. Use a draft gauge to check for a  
downdraft or inadequate draft condition.  
6. After it has been determined that each appliance properly vents when tested as outlined above, return doors, windows, exhaust fans, fire-  
place dampers and any other gas burning appliance to their normal condition.  
7. If improper venting is observed during any of the above tests, a problem exists with either the venting system or the appliance does not  
have enough combustion air (Supply Air from outside) to complete combustion. This condition must be corrected before the appliance can  
function safely.  
NOTE: An unsafe condition exists when the CO reading exceeds 40 ppm and the draft reading is not in excess of - 0.1 in. W.C. (-25 kPa) with  
all of the appliance(s) operating at the same time.  
8. Any corrections to the venting system and / or to the supply (outside) air system must be in accordance with the National Fuel Gas Code  
Z223.1 or CAN/CGA B149.1 Natural Gas and Propane Installation Code (latest editions). If the vent system must be resized, follow the  
appropriate tables in Appendix G of the above codes or for this appliance.  
2. Remove the blower compartment and burner compartment access  
SECTION VIII: START-UP AND  
doors.  
ADJUSTMENTS  
3. Disconnect the gas supply piping at the union to permit removal of  
NOTE: In order that this furnace will operate properly, it is required that  
the entire burner and gas control assembly from the vestibule  
all of the startup procedures in this section be followed.  
panel. Use the wrench boss on the gas valve when removing or  
NOx SCREEN REMOVAL (Lo-NOx Models Only)  
If the furnace is equipped with NOx screens and is to be used with LP  
(propane) gas, the screens must be removed prior to start-up.  
installing the piping.  
4. Unplug the igniter from the wire harness. Disconnect the flame  
sensor wires located on top of the air shield. Unplug the gas valve  
from the wiring harness.  
1. Make sure that the electrical power to the unit is turned off and that  
the gas supply is turned off at the shut-off valve.  
5. Remove the screws holding the burner assembly to the vestibule  
panel.  
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6. Remove the burner assembly. It should be possible to swing the  
burner assembly out of the way without disconnecting the remain-  
ing wires.  
5. To run the furnace at minimum rate (50%), press the ERROR but-  
ton once. The LED will flash one green flash to confirm.  
6. To run the furnace at a middle rate (70%), press the ERROR but-  
ton twice within a five-second period. The LED will flash green two  
times to confirm.  
7. With the burner assembly out of the way, simply slide the NOx  
screens out of the heat exchanger tubes and discard the screens.  
7. To again operate the furnace at maximum (100%) rate, press the  
ERROR button three times within a five-second period. The LED  
will flash green three times to confirm.  
8. Replace all components in reverse order. Reconnect all wiring.  
GAS PIPING LEAK CHECK  
8. If the thermostat call for heat is removed, the LED will flash a rapid  
green signal, indicating that the furnace is still in TEST MODE.  
9. When startup tests are completed, turning off power to the board  
will take the furnace out of TEST MODE and will restore normal  
operation. The furnace will automatically return to normal opera-  
tion after 150 minutes if power is not cycled.  
FIRE OR EXPLOSION HAZARD  
Failure to follow the safety warnings exactly could result in serious  
injury, death or property damage.  
Never test for gas leaks with an open flame. Use a commercially  
available soap solution made specifically for the detection of leaks  
to check all connections. A fire or explosion may result causing  
property damage, personal injury or loss of life.  
CALCULATING THE FURNACE INPUT  
(NATURAL GAS)  
NOTE: Burner orifices are sized to provide proper input rate using natu-  
ral gas with a heating value of 1030 BTU/Ft3 (38.4 MJ/m3). If the heat-  
ing value of your gas is significantly different, it may be necessary to  
replace the orifices.  
NOTE: DO NOT set manifold pressure less than 3.2 in wc or more than  
3.8 in wc for natural gas at sea level. If manifold pressure is outside this  
range, change main burner orifices.  
Burner ignition may not be satisfactory on first startup due to resid-  
ual air in the gas line or until gas manifold pressure is adjusted. The  
ignition control will make three attempts to light before locking out.  
It is recommended that when the gas supply is first connected to the  
furnace, the ground union be loosened until the odor of gas is detected.  
When gas is detected, immediately tighten the union and check for gas  
leaks. Allow five minutes for any gas to dissipate before continuing with  
the startup procedure. Be sure that proper ventilation is available to  
dilute and carry away any vented gas.  
DO NOT bottom out gas valve regulator adjusting screw. This can  
result in unregulated manifold pressure and result in excess over-  
fire 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 sqaurely aligned orifice hole is  
essential for proper flame characteristics.  
With furnace in operation, check all of the pipe joints, gas valve connec-  
tions and manual valve connections for leakage using an approved gas  
detector, a non-corrosive leak detection fluid or other leak detection  
methods. Take appropriate action to stop any leak. If a leak persists,  
replace the faulty component.  
The furnace and its equipment shutoff valve must be disconnected from  
the gas supply during any pressure testing of that system at test pres-  
sures in excess of 1/2 PSI (3.45 kPa).  
DO NOT bottom out gas valve regulator adjusting screw. This can  
result in unregulated manifold pressure and result in excess over-  
fire and heat exchanger failures.  
The furnace must be isolated from the gas supply piping system by  
closing the equipment shutoff valve during any pressure testing of the  
gas supply system.  
Verify natural gas input rate by clocking meter.  
1. Turn off all other gas appliances and pilots.  
SETUP TEST MODE  
2. Run furnace for a minimum of 3 minutes in heating operation.  
During normal operation, the furnace input rate can vary between 50%  
and 100% of full nameplate input, making it difficult to check for proper  
operation. To help with the furnace startup process, the control has a  
TEST MODE available that allows the furnace input rate to stay at a  
constant input rate. To access this TEST MODE perform the following  
sequence:  
3. Measure time (in sec) for gas meter to complete 1 revolution and  
note reading. The 2 cubic feet dial provides a more accurate mea-  
surement of gas flow.  
4. Refer to Table 10, "Gas Rate (CU FT/HR) at Full Input" for cubic  
feet of gas per hour.  
5. Multiply cubic feet per hour by heating valve (BTU/cu ft) to obtain  
input.  
1. With power to the board on and with no thermostat calls (no call for  
heating, cooling or continuous fan), push and hold the TEST but-  
ton on the board for one second. The LED on the board will glow  
red.  
If clocked rate does not match the input rate from the unit nameplate.  
follow steps in next section to adjust the manifold pressure. Repeat  
steps 2 - 5 until correct input is achieved.  
2. Release the TEST button. The LED on the board will flash a rapid  
green signal, indicating that TEST MODE is activated.  
3. Turn the thermostat to call for heat (R & W signal).  
4. The furnace will light and operate at high (100%) firing rate. The  
furnace firing rate should be checked at this level to confirm that  
the furnace is not overfired or underfired.  
Be sure to relight any gas appliances that were turned off at the  
start of this input check.  
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Table 10: Gas Rate (CU FT/HR) at Full Input  
Size of Test Dial  
Size of Test Dial  
Seconds For  
1 Revolution  
Seconds For  
1 Revolution  
1 Cu Ft  
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  
2 Cu Ft  
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  
144  
141  
138  
136  
133  
5 Cu Ft  
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  
360  
355  
346  
340  
333  
1 Cu Ft  
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  
29  
28  
27  
26  
25  
24  
23  
22  
21  
20  
2 Cu Ft  
131  
129  
126  
124  
122  
120  
116  
112  
109  
106  
103  
100  
97  
5 Cu Ft  
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  
145  
141  
135  
130  
125  
120  
115  
110  
105  
100  
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  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
62  
64  
66  
68  
70  
72  
74  
76  
95  
78  
92  
80  
90  
82  
88  
84  
86  
86  
84  
88  
82  
90  
80  
92  
78  
94  
76  
96  
75  
98  
74  
100  
102  
104  
106  
108  
110  
112  
116  
120  
124  
128  
133  
138  
144  
150  
157  
164  
171  
180  
72  
71  
69  
95  
68  
92  
67  
90  
65  
88  
64  
86  
62  
84  
60  
82  
58  
80  
56  
78  
54  
76  
52  
75  
50  
73  
48  
72  
46  
71  
44  
69  
42  
68  
40  
67  
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ADJUSTMENT OF MANIFOLD GAS PRESSURE  
Be sure to relight any gas appliances that were turned off at the  
start of this input check.  
Main  
Regulator  
Adjustment  
On/Off  
Knob  
Table 11: Inlet Gas Pressure Range  
INLET GAS PRESSURE RANGE  
Outlet  
Pressure  
Tap  
Inlet  
Pressure  
Tap  
Natural Gas  
Propane (LP)  
Minimum*  
Maximum  
4.5” W.C. (1.12 kPa)  
10.5” W.C. (2.61 kPa)  
8.0” W.C. (1.99 kPa)  
13.0” (3.24 kPa) W.C.  
FIGURE 29: Gas Valve  
* The gas line pressure MUST BE  
7” W.C. (1.74 kPA) for Natural Gas  
11” W.C. (2.74 kPA) for Propane (LP) Gas  
If gas valve regulator is turned in (clockwise), manifold pressure is  
increased. If screw is turned out (counterclockwise), manifold pres-  
sure will decrease.  
in order to obtain the BTU input specified on the rating plate and/or the  
nominal manifold pressure specified in these instructions and on the  
rating plate.  
7. After the manifold pressure has been adjusted, re-calculate the  
furnace input to make sure you have not exceeded the specified  
input on the rating plate. Refer to "CALCULATING THE FURNACE  
INPUT (NATURAL GAS)".  
The inlet gas pressure operating range table specifies what the  
minimum and maximum gas line pressures must be for the furnace  
to operate safely.  
8. Once the correct BTU (kW) input has been established, turn the  
gas valve to OFF and turn the electrical supply switch to OFF; then  
remove the flexible tubing and fittings from the gas valve pressure  
tap and the pressure reference hose from the burner box and  
replace the pressure tap plugs. Replace the burner box front cover  
(if it was removed) and place the pressure reference hose back on  
the gas valve.  
Follow the appropriate section in the instructions below. Refer to Figure  
29, "Gas Valve" for a drawing of the locations of the pressure ports on  
the gas valve.  
Turn gas off at the ball valve or gas cock on gas supply line  
before the gas valve.  
9. Turn the electrical and gas supplies back on, and with the burners  
in operation, check for gas leakage around the gas valve pressure  
port for leakage using an approved gas detector, a non-corrosive  
leak detection fluid, or other leak detection methods.  
1. The manifold pressure must be taken at the port marked OUT  
PRESS TAP.  
2. The inlet gas line pressure must be taken at the port marked IN  
PRESS TAP.  
ADJUSTMENT OF TEMPERATURE RISE  
3. Using a 3/16” allen wrench, remove the plugs from the inlet and  
outlet pressure ports. Connect a 1/8” UPT barbed hose fitting to  
each pressure port.  
The temperature rise, or temperature difference between the return  
air and the supply (heated) air from the furnace, must be within the  
range shown on the furnace rating plate and within the application  
limitations shown in Table 6, "Ratings & Physical / Electrical Data"  
The supply air temperature cannot exceed the “Maximum Supply  
Air Temperature” specified in these instructions and on the fur-  
nace rating plate. Under NO circumstances can the furnace be  
allowed to operate above the Maximum Supply Air Temperature.  
Operating the furnace above the Maximum Supply Air Temperature  
will cause premature heat exchanger failure, high levels of Carbon  
Monoxide, a fire hazard, personal injury, property damage, and/or  
death.  
The cap for the pressure regulator must be removed entirely to gain  
access to the adjustment screw. Loosening or tightening the cap  
does not adjust the flow of gas.  
4. Refer to Figure 29, "Gas Valve" for location of pressure regulator  
adjustment cap and adjustment screws on main gas valve.  
5. Turn gas and electrical supplies on and follow the operating  
instructions to place the unit back in operation.  
6. Adjust manifold pressure by adjusting gas valve regulator screw  
for the appropriate gas per the following:  
After about 5 minutes of operation, determine the furnace temperature  
rise. Take temperature readings of both the return air and the heated air  
in the ducts about six feet away from the furnace, where they will not be  
affected by radiant heat. Increase or decrease the temperature rise by  
changing the ATR jumper on the furnace control board. The jumper is  
factory-set to deliver an air temperature rise near the midpoint of the  
nameplate temperature rise range. If more air is desired (lower temper-  
ature rise), move the jumper to the -10 position. If less air is desired  
(higher temperature rise), move the jumper to the +10 position.  
TABLE 12: Nominal Manifold Pressure  
NOMINAL MANIFOLD PRESSURE  
Natural Gas (Max)  
Natural Gas (Min)  
3.5" w.c. (0.87 kPa)  
0.9" w.c. (0.22 kPa)  
10.0" w.c. (2.49 kPa)  
2.5" w.c. (0.62 kPa)  
Propane (LP) Gas (Max)  
Propane (LP) Gas (Min)  
Do not move the motor wires to different positions on the  
furnace control board!  
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Continuous Fan Operation - The airflow delivered by the furnace dur-  
ing continuous fan operation can be adjusted as desired. This is done  
my moving the FAN jumper on the control board to give the desired air-  
flow.  
ADJUSTMENT OF FAN CONTROL SETTINGS  
Cooling - The airflow delivered by the furnace during cooling operation  
can be adjusted to match the cooling capacity of the A/C condensing  
unit. This is done by moving the COOL jumper on the control board to  
give the desired airflow.  
Do not move the motor wires to different positions on the  
furnace control board!  
Do not move the motor wires to different positions on the  
furnace control board!  
The jumper has three positions. The "A" position delivers maximum air-  
flow, 100% of the blower capacity. Position "B" delivers approximately  
70% of the blower capacity. And Position "C" delivers minimum airflow,  
approximately 40% of the blower capacity.  
The jumper has four positions, which will deliver sufficient airflow in  
cooling mode for the cooling capacities shown in the table below. The  
CFM delivery on each jumper position is shown in Table 13.  
TABLE 13: Cooling Airflow - A/C Capacity in Tons  
Jumper Position  
Models  
A
3
3
4
4
5
5
B
C
2
D
60/1200  
80/1200  
80/1600  
100/1600  
100/2000  
120/2000  
2-1/2  
2-1/2  
3-1/2  
3-1/2  
4
1-1/2  
1-1/2  
2-1/2  
2-1/2  
3
2
3
3
3-1/2  
3-1/2  
4
3
HUMIDIFIER  
TERMINALS  
EAC  
TERMINALS  
ZONING  
JUMPER  
A T G E V O L  
F L A M E  
HEAT PUMP  
JUMPER  
COOLING  
SPEED  
JUMPER  
CONTINUOUS  
FAN SPEED  
JUMPER  
+ 1 0 F  
N O M  
- 1 0 F  
PRIMARY  
LIMIT  
AUX  
LIMIT  
TEMP  
SENSOR  
TEST  
BUTTON  
SW  
AIR  
O N B U T T E R R O R  
LOW  
VOLTAGE  
TERMINALS  
DIAGNOSTIC  
LIGHT  
LAST ERROR  
BUTTON  
HUMIDISTAT  
JUMPER  
FIGURE 30: Furnace Control Board  
SECTION IX: SAFETY CONTROLS  
CONTROL CIRCUIT FUSE  
A 3-amp fuse is provided on the control circuit board to protect the 24-  
volt transformer from overload caused by control circuit wiring errors.  
This is an ATO 3, automotive type fuse and is located on the control  
board.  
Main power to the unit must still be interrupted at the main power  
disconnect switch before any service or repair work is to be done to  
the unit. Do not rely upon the interlock switch as a main power dis-  
connect.  
Blower and burner must never be operated without the blower  
panel in place.  
BLOWER DOOR SAFETY SWITCH  
This unit is equipped with an electrical interlock switch mounted in the  
burner compartment. This switch interrupts all power at the unit when  
the panel covering the blower compartment is removed.  
ROLLOUT SWITCH CONTROLS  
These controls are mounted on the burner assembly. If the temperature  
in the burner area exceeds its set point, the ignition control and the gas  
valve are de-energized. The operation of this control indicates a mal-  
function in the combustion air blower, heat exchanger or a blocked vent  
pipe connection. Corrective action is required. These are manual reset  
controls that must be reset before operation can continue.  
Electrical supply to this unit is dependent upon the panel that covers the  
blower compartment being in place and properly positioned.  
24  
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5. The furnace fires at 70% of full rate for 30-45 seconds, then drops  
to the minimum (50%) firing rate.  
PRESSURE CONTROLS  
Pressure Sensor - This furnace is equipped with a pressure sensor in  
the burner compartment near the combustion blower. This sensor mon-  
itors combustion airflow through furnace and piping systems. If any of  
the conditions listed below are detected by the pressure sensor, the  
control board will prevent a hazardous condition from occurring by  
speeding up the combustion blower motor in order to maintain ade-  
quate combustion airflow. If the combustion blower is already turning at  
full speed, the furnace control will then start reducing the input to the  
furnace in order to maintain proper combustion with the amount of com-  
bustion airflow available. If there is not enough combustion air available  
to give proper combustion even at the minimum input rate (50%), the  
control will close the gas valve and shut off the burners. The sensor will  
detect the following conditions.  
6. The firing rate is automatically adjusted to meet demand, increas-  
ing gradually to maximum (100%) firing rate if the thermostat is not  
satisfied within a defined time.  
7. When the thermostat R and W contacts open (thermostat is satis-  
fied) the furnace control recalculates the demand and a new firing  
rate.  
A. If demand exceeds the minimum firing rate, the burners will  
continue to fire at a recalculated reduced firing rate, decreas-  
ing if the thermostat remains off for a defined time.  
b. If demand does not exceed the minimum firing rate, the burn-  
ers will shut off immediately.  
8. After the burners shut off, the circulating blower will continue to run  
until the temperature sensor detects that the supply air tempera-  
ture has dropped to the desired level, which should take from 30 to  
90 seconds.  
1. Blockage of vent piping or vent terminal  
2. Failure of combustion air blower motor or blower wheel.  
Pressure Switch - This furnace is equipped with a pressure switch  
mounted on the furnace vestibule panel. This switch monitors the flow  
through the vent system. The switch will close at the beginning of each  
cycle when adequate combustion airflow is established. However, this  
switch may be open under certain conditions when the burners are lit.  
The pressure sensor is the primary flow sensor.  
FURNACE CONTROL DIAGNOSTICS  
This furnace has built-in self-diagnostic capability. If a system problem  
occurs, a flashing LED shows a fault code. The LED can flash red,  
green or amber to indicate various conditions. The LED is located on  
the furnace control board and can be seen through the clear view port  
in the lower door of the furnace. To indicate an error condition, the LED  
will turn on for 1/4 second and off for 1/4 second. The pattern will be  
repeated the number of times equal to the flash code. For instance, a  
"six flash code" will be indicated by the LED turning on and off six times.  
There will be a two second off period between each set of flashes. The  
flash codes and an indication of their likely causes are listed below:  
LIMIT CONTROLS  
Limit Switch - This furnace is equipped with a high temperature limit  
control mounted to the left side of the furnace vestibule panel. This limit  
switch will open and shut off gas to the burners if it detects excessive air  
temperature in the furnace, which can be caused by any of the following  
conditions:  
STEADY OFF - No 24V power to board. Check the 24 volt control cir-  
cuit fuse on the board. Check the circuit breaker or fuse on the 115 volt  
supply power to the furnace. Check that the 24 volt transformer.  
1. Dirty filter  
2. Failure of the circulating blower motor or wheel  
3. Too many supply or return registers closed or blocked.  
One Green Flash - Normal Operation with no call for heat.  
Temperature Sensor - This furnace is also equipped with a tempera-  
ture sensor mounted to the left side of the vestibule panel, near the limit  
switch. This sensor monitors the temperature of the air being supplied  
to the home. If the sensor detects air temperature higher than normal,  
the furnace control will first speed up the circulating blower motor in  
order to try to increase the amount of airflow being delivered, thereby  
reducing the air temperature. If the blower motor is already turning at  
full speed, the control will then start reducing the input to the furnace to  
try to reduce the air temperature. If the supply air temperature is too  
high even at the minimum input rate (50%), the control will close the  
gas valve and shut off the furnace.  
Two Green Flashes - Indicator for "No error codes in memory". See  
Diagnostic Fault Code Storage and Retrieval section below.  
Three Green Flashes - Indicator for "Error codes cleared from mem-  
ory". See Diagnostic Fault Code Storage and Retrieval section below.  
Rapid Green Flash - Control is in "Factory Speedup" mode. This mode  
is used only during factory run-testing of the furnace. To stop this mode,  
cycle power to the furnace off and then back on.  
One Amber Flash - Normal operation with call for cooling.  
Two Amber Flashes - Normal operation with call for heat.  
Three Amber flashes - Normal operation, burner is on at end of heat-  
ing cycle after wall thermostat has been satisfied.  
SECTION X: NORMAL OPERATION AND  
DIAGNOSTICS  
NORMAL OPERATION SEQUENCE  
The furnace control calculates the optimum firing rate each time the  
wall thermostat R and W contacts close or open (at the beginning and  
at the end of each call for heat) based on information from the thermo-  
stat and past demand. UNLIKE CONVENTIONAL SYSTEMS, THE  
WALL THERMOSTAT DOES NOT SIMPLY TURN THE FURNACE ON  
AND OFF. THE FURNACE CONTROL CALCULATES THE DEMAND  
AND MAY CONTINUE TO FIRE THE FURNACE DURING PORTIONS  
OF THE THERMOSTAT "OFF" CYCLE.  
Four Amber Flashes - Heating capacity is reduced due to restriction in  
the circulating air system. Check for dirty filter or closed registers.  
Five Amber Flashes - Heating capacity is reduced due to restriction in  
the combustion air or vent system. Check for blocked vent/air pipe or  
clogged condensate drain. Above 4,000 feet altitude, this may also indi-  
cate automatic, normal derating for altitude. See page 7 for additional  
high altitude information.  
Six Amber Flashes - (Heat Pump applications only) Normal operation  
with call for heat pump heating.  
Rapid Amber Flash - Low flame sense current. Check for dirty or mis-  
located flame sensor rod.  
When the wall thermostat R and W contacts close, indicating a call for  
heat, the following sequence occurs:  
One Red Flash - Flame is present with no power being supplied to gas  
valve. This can be caused by a gas valve that is slow to close or that  
leaks gas through to the burners.  
1. The inducer is energized and ramps up its speed until airflow is  
proven by the pressure switch and by the pressure sensor on the  
control board.  
Two Red Flashes - Stuck closed pressure switch. The control confirms  
that the pressure switch contacts are open at the beginning of each  
cycle. This could be caused by a faulty pressure switch or by mis-wiring  
of the pressure switch.  
2. The hot surface ignitor is energized.  
3. After a 17-20 second igniter heatup, the gas valve opens and the  
burners light.  
4. When the control senses that flame is present, the circulating  
blower starts at low speed.  
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Three Red Flashes - Stuck open pressure switch. This indicates that  
the pressure switch is open when it should be closed. This could be  
caused by a faulty combustion air blower, blocked vent pipe, blocked air  
intake pipe, blocked condensate drain, faulty pressure switch hose or a  
faulty pressure switch.  
Twelve Red Flashes - ID plug is not present or not connected properly,  
check for loose plug or loose wires in plug.  
Steady On Red - Control fault has been detected or there is 24 volts  
present without 115 volts. Check that there is 24 volts and 115 volts  
being supplied to the board. If so, then the board should be replaced.  
Four Red Flashes - High limit switch open or 24 volt fuse is open. This  
may be caused by a dirty air filter, improperly sized duct system, faulty  
blower motor, restricted circulating airflow or an open fuse on the con-  
trol board.  
IGNITION CONTROL FLAME SENSE LEVELS  
Normal flame sense current is approximately  
3.7 microamps DC (µa)  
Low flame signal warning starts at 1.5 microamps.  
Low flame signal control lockout point is  
0.1 microamps DC (µa)  
Five Red Flashes - Rollout switch or auxiliary limit switch open. Check  
the rollout switch on the side of the burner box. It is a manual reset  
switch. To reset, push the small button in the center of the switch. If it  
cannot be reset or if the switch trips again, contact a qualified service-  
man. Check the limit switch mounted in the combustion air blower hous-  
ing.  
DIAGNOSTIC FAULT CODE STORAGE AND  
RETRIEVAL  
The control in this furnace is equipped with memory that will store up to  
five error codes to allow a service technician to diagnose problems  
more easily. This memory will be retained even if power to the furnace  
is lost. Only a qualified service technician should use this feature.  
Six Red Flashes - Current failure on modulating gas valve.  
Seven Red Flashes - Lockout due to no ignition. The control will try  
three times for ignition. If flame cannot be established in three tries, the  
control will lockout for one hour and then will try again to light. Check  
gas supply, ignitor, gas valve, flame sensor.  
The control stores up to five separate error codes. If more than five  
error codes have occurred since the last reset, only the five most recent  
will be retained. The furnace control board has a button, labeled "LAST  
ERROR" that is used to retrieve error codes. This function will only  
work if there are no active thermostat signals. So any call for heating,  
cooling or continuous fan must be terminated before attempting to  
retrieve error codes.  
Eight Red Flashes - Lockout due to too many flame recycles. This  
flash code occurs if flame is lost five times during a single heating cycle.  
This could be caused by a faulty gas valve, low gas pressure, or dirty  
flame sensor. The control will lock out for one hour and then will try  
again.  
To retrieve the error codes, push the LAST ERROR button. The LED on  
the control will then flash the error codes that are in memory, starting  
with the most recent. There will be a two-second pause between each  
flash code. After the error codes have all been displayed, the LED will  
resume the normal slow green flash after a five second pause. To  
repeat the series of error codes, push the button again.  
Nine Red Flashes - Reversed line polarity or improper grounding.  
Check polarity of the incoming power to the furnace. Check the ground-  
ing of the furnace, including the transformer ground and the L1 and  
neutral connections.  
Ten Red Flashes - Gas valve circuit shorted. Check gas valve wiring. If  
If there are no error codes in memory, the LED will flash two green  
flashes. To clear the memory, push the LAST ERROR button and hold it  
for more than five seconds. The LED will flash three green flashes  
when the memory has been cleared, then will resume the normal slow  
green flash after a five-second pause.  
correct, replace gas valve.  
Eleven Red Flashes - Main blower failure - This flash code occurs  
when the main limit opens and fails to reclose within five minutes, indi-  
cating that the blower motor or blower wheel has failed.  
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SECTION XI: REPLACEMENT PARTS LIST  
DESCRIPTION  
DESCRIPTION  
FABRICATED PARTS Continued  
BRACKET, BLOWER TRACK (2 Req’d)  
HEAT EXCHANGER ASS’Y  
MANIFOLD, GAS  
MOTOR  
MOTOR, DIRECT DRIVE BLOWER  
BLOWER, COMBUSTION  
ELECTRICAL  
PAN, BOTTOM  
CAPACITOR, RUN  
PANEL, TOP  
SWITCH, LIMIT  
PANEL, DOOR (2 Req’d)  
VENT PAN, COMBUSTION (w/Gasket)  
PANEL, BLOCKOFF  
CONTROL, FURNACE  
IGNITER  
SENSOR, FLAME  
LO-NOX SCREEN (L-Models Only)  
MISCELLANEOUS  
SWITCH, PRESSURE  
SWITCH, DOOR  
ORIFICE, BURNER (Natural #45)  
SIGHT GLASS, OVAL (2 Req’d)  
GASKET, FOAM (Door) (1.5 ft req’d)  
GASKET, INTAKE PAN  
PLUG, VENT HOLE  
TRANSFORMER  
VALVE, GAS  
CONTROL, TEMPERATURE  
SENSOR, PRESSURE  
SENSOR, THERMISTOR  
AIR MOVING  
BRACKET, DOOR  
WIRING HARNESS  
HOUSING, BLOWER  
WHEEL, BLOWER  
FERRULE (3 Req’d)  
GROMMET (3 Req’d)  
FABRICATED PARTS  
BAFFLE, FLUE  
MOTOR MOUNT  
HOSE ASSY, VACUUM  
PLUG, ID (Control Board)  
KNOB, QUARTER TURN (4 Req’d)  
UNION  
BURNER, MAIN GAS  
BRACKET, IGNITER  
SHELF, BLOWER  
RAIL, BLOWER (2 Req’d)  
DIAGRAM, WIRING  
REPLACEMENT PART CONTACT INFORMATION  
This is a generic parts list. To request a complete parts list, refer to the contact information below:  
1. Search for a part or browse the catalog.  
2. Find a dealer or distributor.  
3. Customer Service contact information.  
a. Click on the “Brand Links” button  
b. Click on the “Customer Service” button  
You can contact us by mail. Just send a written request to:  
Johnson Controls Unitary Products  
Consumer Relations  
5005 York Drive  
Norman, OK 73069  
Johnson Controls Unitary Products  
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SECTION XII: WIRING DIAGRAM  
FIGURE 31: Wiring Diagram  
Subject to change without notice. Printed in U.S.A.  
Copyright © 2008 by Johnson Controls, Inc. All rights reserved.  
368261-UIM-A-0508  
Supersedes: Nothing  
Johnson Controls Unitary Products  
5005 York Drive  
Norman, OK 73069  
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