Lennox International Inc Air Conditioner Lennox Air Handler User Manual

INSTALLATION  
INSTRUCTIONS  
E2012 Lennox Industries Inc.  
Dallas, Texas, USA  
Merit® CBX25UH Series  
Units  
AIR HANDLERS  
506757-01 (0659371-80)  
10/2012  
Litho U.S.A.  
Table of Contents  
Shipping and Packing List . . . . . . . . . . . . . . . . . . . . . .  
CBX25UH Series Units . . . . . . . . . . . . . . . . . . . . . . . . .  
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Installation Clearances . . . . . . . . . . . . . . . . . . . . . . . . .  
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Condensate Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Duct System and Filters . . . . . . . . . . . . . . . . . . . . . . . .  
Connecting Refrigerant Lines . . . . . . . . . . . . . . . . . . .  
Sealing the Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . .  
THIS MANUAL MUST BE LEFT WITH THE  
HOMEOWNER FOR FUTURE REFERENCE  
Airflow - Cooling Blower Speed . . . . . . . . . . . . . . . . . . 10  
Check-Out Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 12  
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12  
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
Cabinet Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
WARNING  
Improper installation, adjustment, alteration, service or  
maintenance can cause personal injury, loss of life, or  
damage to property.  
Shipping and Packing List  
Package 1 of 1 contains the following:  
Installation and service must be performed by a licensed  
professional installer (or equivalent) or a service agency.  
1 - Assembled air handler unit for upflow or horizontal air  
discharge application (includes upflow and horizontal  
drain pans and pre-installed air filter).  
Check equipment for shipping damage. If found,  
immediately report damage to the last carrier. Check the  
unit rating plate to confirm that delivered unit matches  
order.  
IMPORTANT  
The Clean Air Act of 1990 bans the intentional venting of  
refrigerant (CFCs, HCFCs and HFCs) as of July 1, 1992.  
Approved methods of recovery, recycling or reclaiming  
must be followed. Fines and/or incarceration may be  
levied for noncompliance.  
General  
The CBX25UH air handler is designed for indoor  
installation only. As shipped, the unit is ready for  
installation in either upflow, horizontal left-hand and  
right-hand air discharge applications. Electric heat, down  
flow air discharge application kits, air filters and other  
various accessories are available and listed in the  
CBX25UH Product Specification bulletin for ordering.  
WARNING  
The State of California has determined that this product  
may contain or produce a chemical or chemicals, in very  
low doses, which may cause serious illness or death. It  
may also cause cancer, birth defects, or reproductive  
harm.  
All units come with a factory installed check/expansion  
valve.  
10/2012  
506757-01 (0659371-80)  
Page 1  
*2P102012*  
*P506757-01*  
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Do not remove the cabinet knockouts until it has been  
determined which knockouts will need to be removed for  
the installation.  
Requirements  
WARNING  
Excessive Weight Hazard - Use two or more people  
when moving and installing the unit. Failure to do so can  
result in back or other type of injury.  
Select the final air discharge position which best suits the  
site conditions. Consider required clearances, space,  
routing requirements for refrigerant line, condensate  
disposal, filters, duct system, wiring, and accessibility for  
service. Refer to the air handler rating plate on the air  
handler for specific information.  
IMPORTANT  
WARNING  
The CBX25UH units are designed to match, and must be  
used with, outdoor units as rated. The indoor sections  
are manufactured with a check/expansion valve (TXV)  
to provide optimum refrigerant control and system  
performance with a variety of different capacities of out-  
door units.  
Danger of explosion. Keep flammable ma-  
terials and vapors, such as gasoline, away  
from air handler. Place air handler so that  
heating elements are at least 18 inches (46  
cm) above the floor for a garage installa-  
tion. Failure to follow these instructions  
can result in death, explosion, or fire.  
CAUTION  
NOTES —  
Physical contact with metal edges and corners while  
applying excessive force or rapid motion can result in  
personal injury. Be aware of, and use caution when  
working near these areas during installation or while  
servicing this equipment.  
During cooling operation, excessive sweating may occur if  
the air handler is installed in a warm and humid space.  
If installed in an unconditioned space, sealant should be  
applied around the electrical wires, refrigerant tubing, and  
condensate lines where they enter the cabinet.  
These instructions are intended as a general guide and do  
not supersede local or national codes in any way. Consult  
authorities having jurisdiction before installation.  
Electrical wires should be sealed on the inside where they  
exit the conduit opening. Sealant is required to prevent air  
leakage into, and condensate from forming inside of, the  
air handler, the control box, and on the electrical controls.  
Compliance with all local, state, or national codes  
pertaining to this type of equipment should be determined  
prior to installation. Read this instruction manual, as well  
as the instructions supplied in separate equipment, before  
starting the installation.  
This unit is approved for installation clearance to  
combustible material as stated on the unit rating plate.  
Accessibility and service clearances must take  
precedence over combustible material clearances.  
In addition to conforming to manufacturer's installation  
instructions and local municipal building codes, installation  
of Lennox air handler units (with or without optional electric  
heat), MUST conform with National Fire Protection  
Association (NFPA) standards: “Standard for Installation  
of Air Conditioning and Ventilation Systems” (NFPA No.  
90A) and “Standard for Installation of Residence Type  
Warm Air Heating and Air Conditioning Systems” (NFPA  
No. 90B).  
The air handler must be installed so that free access is  
allowed to the coil/filter compartment and blower/control  
compartment.  
Installation Clearances  
NON-DUCTED RETURN CLOSET INSTALLATION  
The air handler can be installed in a closet with a false  
bottom to form a return air plenum. It may also be installed  
with a return air plenum under the air handler.  
All models are designed for indoor installation only. The  
installation of the air handler, field wiring, duct system, etc.  
must conform to the requirements of the National Electrical  
Code, ANSI/NFPA No. 70 (latest edition) in the United  
States, and any state laws, and local ordinances (including  
plumbing or wastewater codes). Local authorities having  
jurisdiction should be consulted before installation is  
made. Such applicable regulations or requirements take  
precedence over the general instructions in this manual.  
Louvers or return air grilles are field‐supplied. Local codes  
may limit application of systems without a ducted return to  
single story buildings.  
When a CBX25UH unit is installed in a closet with a  
louvered return opening, the minimum open area for the  
louvers will be:  
S
S
S
320 square inches for -018 and -024 models;  
360 square inches for -030 and -036 models;  
450 square inches for -042 thru -060 models.  
Install the conditioned air plenum, ducts and air filters  
(provided) in accordance with NFPA 90B Standard for the  
Installation of Warm Air Heating and Air-Conditioning  
Systems (latest edition).  
If the free area is not known, assume a 25% free area for  
wood or a 75% free area for metal louvers or grilles. Using  
the louver dimensions and the 25% or 75% assumption,  
determine if the open area meets the minimum open area  
listed above.  
The air handler is shipped from the factory completely  
assembled. The unit is provided with flanges for the  
connection of the duct system.  
Page 3  
CBX25UH SERIES  
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If a return air plenum is used, the return air grille should be  
immediately in front of the opening in the plenum to allow  
for the free flow of return air. When not installed in front of  
the opening, there must be adequate clearance around the  
air handler to allow for the free flow of return air.  
HORIZONTAL APPLICATIONS  
IMPORTANT  
When removing the coil, there is possible danger of  
equipment damage and personal injury. Be careful when  
removing the coil assembly from a unit installed in right-  
or left-hand applications. The coil may tip into the drain  
pan once it is clear of the cabinet. Support the coil when  
removing it.  
Installation  
Each unit consists of a blower assembly, refrigerant coil,  
and controls, in an insulated galvanized steel factory  
finished enclosure. Knockouts are provided for electrical  
wiring entrance.  
ANGLE IRON OR SHEET  
METAL  
ELECTRICAL INLET CLEAR-  
ANCE 4 IN. (102 MM)  
For ease in installation, it is best to make any necessary  
coil configuration changes before setting air handler in  
place.  
MAXIMUM 1/2”  
LONG SCREW  
REFRIGERANT METERING DEVICE  
CB25UH units are equipped with a factory-installed check  
expansion valve.  
AIR FLOW  
UPFLOW APPLICATION  
1. The air handler must be supported on the bottom only  
and set on solid floor or field‐supplied support frame.  
Securely attach the air handler to the floor or support  
frame.  
FRONT VIEW  
END VIEW  
Figure 2. Suspending Horizontal Unit  
2. If installing a unit in an upflow application, remove the  
horizontal drain pan. IMPORTANT - The horizontal drain pan  
is not required in upflow air discharge installations; its removal  
provides the best efficiency and air flow.  
NOTE — When the unit is installed in horizontal  
applications, a secondary drain pan is recommended.  
Refer to local codes.  
NOTE — This unit may be installed in left-hand or  
right-hand air discharge horizontal applications. Adequate  
support must be provided to ensure cabinet integrity.  
Ensure that there is adequate room to remove service and  
access panels if installing in the horizontal position.  
3. Place the unit in the desired location and slope unit as  
previously mentioned. Connect return and supply air  
plenums as required using sheet metal screws.  
4. Install units that have no return air plenum on a stand  
that is at least 14” from the floor. This will allow proper  
air return.  
LEFT-HAND DISCHARGE  
1. Determine knockouts required for drain line  
connections.  
HORIZONTAL DRAIN PAN  
IMPORTANT! REMOVE PAN  
FOR BEST EFFICIENCY  
AND AIR FLOW.  
2. With access door removed, knock out drain line  
opening for installing drain lines.  
3. Set unit so that it is sloped toward the drain pan end of  
the unit (see figure 10).  
HORIZONTAL DRAIN  
CONNECTIONS  
UPFLOW  
(BOTH SIDES; NOT  
DRAIN PAN  
USED)  
AIR FLOW  
UPFLOW DRAIN CON-  
NECTIONS (BOTH  
SIDES; USE ONE SIDE  
OR OTHER)  
Drains  
LEFT‐HAND DRAINS  
KNOCKOUT  
Figure 1. Upflow Configuration  
Figure 3. Left‐Hand Discharge Configuration  
Page 4  
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5. If the unit is suspended, the entire length of the cabinet  
must be supported. If you use a chain or strap, use a  
piece of angle iron or sheet metal attached to the unit  
(either above or below) to support the length of the  
cabinet. Use securing screws no longer than 1/2 inch  
to avoid damaging the coil or filter. See figure 2. Use  
sheet metal screws to connect the return and supply  
air plenums as required.  
3. Remove coil assembly, bottom drain pan and  
horizontal drain pan as one assembly from the air  
handler.  
4. Move the horizontal drain pan to the opposite side of  
the coil. Be sure drain holes toward the back of the unit  
are plugged. Remove the plugs from the front drain  
pan ports.  
RIGHT-HAND AIR DISCHARGE  
5. Re-install modified coil/drain pan assembly in air  
handler in the same orientation as before (figures 6  
and 7).  
For horizontal right-hand air discharge, the following field  
modifications are required.  
1. Remove and set aside blower and coil access covers.  
2. Remove bracket(s) securing pan(s) to unit as  
INSTALL BRACKET  
SECURING MAIN  
DRAIN PAN TO UNIT.  
Figure 6. Install Main Drain Pan Mounting Bracket  
(-018 through -036)  
REMOVE BRACKET  
SECURING MAIN  
DRAIN PAN TO UNIT.  
Figure 4. Remove Main Drain Pan Mounting Bracket  
(-018 through -036)  
REMOVE BRACKETS  
SECURING BOTH  
DRAIN PANS TO UNIT.  
REMOVE BRACKETS  
SECURING BOTH  
DRAIN PANS TO UNIT.  
Figure 7. Install both Horizontal and Main Drain Pan  
Brackets (-042 through -060)  
6. Remove two screws securing the blow-off prevention  
bracket. Rotate the brackets 180º and reinstall using  
Figure 5. Remove Horizontal and Main Drain Pan  
Mounting Brackets (-042 through -060)  
Page 5  
CBX25UH SERIES  
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HORIZONTAL RIGHT  
REMOVE 2 SCREWS  
SECURING BLOW OFF  
PREVENTION BRACKET  
HORIZONTAL LEFT  
(FACTORY DEFAULT)  
ROTATE BRACKET TO THIS  
POSITION AND REINSTALL  
Figure 8. Blow-Off Prevention Plate  
Condensate Drain  
IMPORTANT  
On units of this type, where the blower “draws” rather than “blows” air through the coil, traps must be installed in the con-  
densate drain lines (primary and auxiliary, if used). Traps prevent the blower from drawing air through the drain lines into  
the air supply.  
OVERFLOW DRAIN LINE  
ABOVE  
FINISHED  
ALWAYS RUN AN OVERFLOW DRAIN LINE. IF NOT POSSIBLE TO  
ROUTE OVERFLOW DRAIN LINE, INSTALL LOW VOLTAGE  
SPACE?  
VENT MUST EXTEND  
ABOVE HEIGHT OF  
COIL DRAIN PAN BY  
TWO INCHES (51MM)  
OVERFLOW SWITCH KIT. WIRE KIT TO SHUT DOWN  
COMPRESSOR PER INSTRUCTIONS.  
VENT  
LENNOX #  
X3169  
CLEAN OUT  
PRESS IN  
(DO NOT GLUE)  
COMPACT OVERFLOW SWITCH WITH 3/4” FEMALE SLIP INLET  
AND MALE ADAPTER, TWO PART DESIGN FOR USE WHERE  
OBSTRUCTIONS PREVENT DIRECT THREADING  
NO  
MAIN  
DRAIN  
1” X 3/4” X 3/4”  
REDUCING  
TEE WITH  
PLUG  
AIR HANDLER DRAIN PAN  
OVERFLOW  
DRAIN  
YES  
NOTE — WHEN A AIR HANDLER IS LOCATED  
ABOVE A FINISHED SPACE THE SECONDARY  
DRAIN PAN MUST HAVE A LARGER FOOTPRINT  
THAN THE AIR HANDLER.  
WHEN A COIL IS LOCATED ABOVE A FINISHED  
SPACE, A 3/4” (19.1MM) SECONDARY DRAIN LINE  
MUST BE:  
1
LENNOX P-TRAP  
S
S
CONNECTED TO SECONDARY DRAIN PAN  
OR  
49P66, J-TRAP #  
91P90 OR ANY  
PVC SCH 40 P- OR  
J-TRAP 3/4”  
SECONDARY  
DRAIN PAN  
2”  
(51MM)  
CONNECTED TO THE OVERFLOW DRAIN  
OUTLET OF THE AIR HANDLER DRAIN PAN.  
TRAPS MUST BE DEEP ENOUGH TO OFFSET MAXIMUM STATIC DIFFERENCES  
GENERALLY, TWO INCHES (51MM).  
TRAP DEPTH  
TO APPROVED  
DRAIN  
1
LENNOX P-TRAP 49P66 REQUIRES A LARGER INSTALLATION SPACE THAN THE J-TRAP 91P90.  
PIPE NIPPLE PROVIDED IN BAG ASSEMBLY - SCH 80, 3/4” I. D. X 5” - 34K7401 (1): CUT THE PIPE  
IN HALF AND USE IT TO ROUTE THE MAIN DRAIN.  
FOR NEGATIVE PRESSURE COILS (BLOWER  
AFTER COIL) TRAPS ARE REQUIRED ON ALL  
DRAIN LINES CONNECTED TO COIL.  
2
DRAIN LINE SHOULD  
SLOPE A MINIMUM OF  
ONE INCH PER 10  
FEET (25MM PER  
METERS)  
3
Figure 9. Typical Main and Overflow Drain  
Page 6  
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5. Make sure drain ports and drain pan are free of all  
debris.  
IMPORTANT  
6. Plug and check any unused drain pan openings for  
tightness. Torque plugs to 30 in. lb. to prevent water  
leaks or seepage from the drain pan.  
A field-fabricated secondary drain pan, with a drain pipe  
to the outside of the building, is required in all installa-  
tions over a finished living space or in any area that may  
be damaged by overflow from the main drain pan. In  
some localities, local codes may require a secondary  
drain pan for any horizontal installation.  
7. Install a 2” trap in the primary drain lines as close to the  
unit as practical (see figure 9). Make sure the top of the  
trap is below the connection to the drain pan to allow  
complete drainage of the pan.  
The air handler is provided with ¾” NPT condensate drain  
connections.  
NOTE — Horizontal runs must have an anti-siphon air vent  
(standpipe) installed ahead of the horizontal run (See  
figure 9). An extremely long horizontal run may require an  
oversized drain line to eliminate air trapping.  
SLOPING THE DRAIN  
Make sure the unit is sloped (similar to the slope shown in  
figure 10) (horizontal or upflow) so that the drain pan will  
empty completely without water standing in the pan.  
NOTE — Do not operate air handler without a drain trap.  
The condensate drain is on the negative pressure side of  
the blower; therefore, air being pulled through the  
condensate line will prevent positive drainage without a  
proper trap.  
THIS CORNER SHOULD BE 5/8” (+/- 1/8”) HIGHER  
THAN DRAIN CORNER  
8. Route the drain line to the outside or to an appropriate  
drain. Drain lines must be installed so they do not block  
service access to the front of the air handler. A 24”  
clearance is required for filter, coil, or blower removal  
and service access.  
THIS CORNER SHOULD BE  
5/8” (+/- 1/8”) HIGHER THAN  
DRAIN CORNER  
NOTE — Check local codes before connecting the drain  
line to an existing drainage system.  
Insulate the drain lines where sweating could cause water  
damage.  
DRAIN CORNER  
TEST CONDENSATE DRAIN  
Test the drain pan and drain line after installation:  
1. Pour several quarts of water into drain pan, enough to  
fill drain trap and line.  
Figure 10. Sloping the Drain  
2. Check to make sure the drain pan is draining  
completely, no leaks are found in drain line fittings, and  
water is draining from the end of the primary drain line.  
INSTALL CONDENSATE DRAIN  
1. Remove the appropriate drain knockouts. If  
necessary, remove the indoor coil assembly from the  
cabinet.  
3. Correct any leaks found.  
Duct System and Filters  
2. Connect primary drain line connection to the primary  
drain pan connection. The primary drain connection is  
flush with the bottom of the inside of the pan.  
Secondary connection is raised above the bottom of  
the inside of the pan.  
DUCT SYSTEM  
The air handler is provided with flanges for the connection  
of the plenum and ducts. The air handler is equipped with  
flanges that can form a filter rack for the installation of the  
air filter, or the filter may be installed as part of the return air  
duct system.  
NOTE — When making drain fitting connections to the  
drain pan, hand tighten the fitting and use a thread sealant.  
Over-tightening the fittings can split connections on the  
drain pan.  
Supply and return duct system must be adequately sized  
to meet the system's air requirements and static pressure  
capabilities. The duct system should be insulated with a  
minimum of 1” thick insulation with a vapor barrier in  
conditioned areas or 2” minimum in unconditioned areas.  
3. If the auxiliary drain line is to be used, remove the plug  
and route the drain line so that water draining from the  
outlet will be easily noticed by the homeowner. The  
auxiliary drain line does not require venting or a trap.  
Refer to local codes.  
Table 1. Unit Air Filter Size Chart  
Model  
Filter Size  
Actual Minimum  
Filter Size  
4. After removal of drain pan plugs, check the drain port  
to see if holes have been drilled. If not drilled, use a  
19/32” bit to drill out the primary drain hole; use a 3/8”  
drill bit for the secondary drain hole. Remove all drill  
shavings.  
-018  
12” x 20” x 1 11.50” x 19.50” x .75”  
15” x 20” x 1 14.50” x 19.50” x .75”  
18” x 20” x 1 17.50” x 19.50” x .75”  
18” x 24” x 1 17.50” x 23.50” x .75”  
-024 and -030  
-036  
-042, -048 and -060  
Page 7  
CBX25UH SERIES  
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2. Make sure that the suction line is insulated over the  
entire exposed length and that neither suction nor  
liquid lines are in direct contact with floors, walls, duct  
system, floor joists, or other piping.  
IMPORTANT  
If a high-efficiency filter is being installed as part of this  
system to ensure better indoor air quality, the filter must  
be properly sized. High-efficiency filters have a higher  
static pressure drop than standard-efficiency glass/foam  
filters. If the pressure drop is too great, system capacity  
and performance may be reduced. The pressure drop  
may also cause the limit to trip more frequently during the  
winter and the indoor coil to freeze in the summer, result-  
ing in an increase in the number of service calls.  
3. Connect the suction and liquid lines to the evaporator  
coil.  
4. To avoid damaging the rubber grommets in the cabinet  
while brazing, slide the rubber grommets over the  
refrigerant lines until they are away from the heat  
source.  
5. Braze using an alloy of silver or copper and  
phosphorus with a melting point above 1,100°F  
(593°C).  
Before using any filter with this system, check the spe-  
cifications provided by the filter manufacturer against the  
data given in the appropriate Lennox Product Specifica-  
tions bulletin. Additional information is provided in Ser-  
vice and Application Note ACC-00-2 (August 2000).  
NOTE — Do not use soft solder.  
6. Reinstall the rubber grommets after brazing is  
finished.  
7. Make sure outdoor unit has been put in place  
according to the Installation Instructions and is  
connected to the refrigerant lines.  
Supply plenum should be the same size as the flanged  
opening provided around the blower outlet and should  
extend at least 3 ft. from the air handler before turning or  
branching off plenum into duct runs. The plenum forms an  
extension of the blower housing and minimizes air  
expansion losses from the blower.  
Sealing the Unit  
Seal the unit so that warm air is not allowed into the  
cabinet. Warm air introduces moisture, which results in  
water blow-off problems. This is especially important when  
the unit is installed in an unconditioned area.  
INSTALLING DUCT SYSTEM  
Connect supply air duct to the flange on top of the air  
handler. If an isolation connector is used, it must be  
nonflammable.  
If installed in an unconditioned space, sealant should be  
applied around the electrical wires, refrigerant tubing, and  
condensate lines where they enter the cabinet.  
A return air duct system is recommended. If the unit is  
installed in a confined space or closet, a return connection  
must be run, full size, to a location outside the closet.  
WARNING  
There must be an airtight seal between the bottom of the  
air handler and the return air plenum. Use fiberglass  
sealing strips, caulking, or equivalent sealing method  
between the plenum and the air handler cabinet to  
ensure a tight seal. Return air must not be drawn from a  
room where this air handler or any gas-fueled appliance  
(i.e., water heater), or carbon monoxide-producing  
device (i.e., wood fireplace) is installed.  
Connecting Refrigerant Lines  
Refrigerant lines must be connected by a qualified  
technician in accordance with established procedures.  
IMPORTANT  
Refrigerant lines must be clean, dehydrated, refrig-  
erant-grade copper lines. Air handler coils should be  
installed only with specified line sizes for approved sys-  
tem combinations.  
IMPORTANT  
When sealing the cabinet, be sure to seal closed any  
space around the holes where the drain lines exit the  
cabinet using duct tape and/or Permagum. Warm air  
must not be allowed to enter through any gaps or holes  
in the cabinet.  
Handle the refrigerant lines gently during the installation  
process. Sharp bends or possible kinking in the lines will  
cause a restriction.  
Do not remove the caps from the lines or system connec-  
tion points until connections are ready to be completed.  
Make sure the liquid line and suction line entry points are  
sealed with either ARMAFLEX material or with  
Permagum. Permagum may also be used to seal around  
the main and auxiliary drains and around open areas of  
electrical inlets.  
1. Route the suction and liquid lines from the fittings on  
the indoor coil to the fittings on the outdoor unit. Run  
the lines in as direct a path as possible avoiding  
unnecessary turns and bends.  
Page 8  
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1. Disconnect all power supplies.  
Electrical Connections  
2. Remove the air handler access panel.  
3. Route the field supply wires to the air handler electrical  
connection box.  
WARNING  
Electric shock hazard! - Disconnect all  
power supplies before servicing.  
4. Use UL-listed wire nuts to connect the field supply  
conductors to the unit black and yellow leads, and the  
ground wire to ground terminal marked GND.  
Replace all parts and panels before op-  
erating.  
5. Replace the air handler access panel.  
Failure to do so can result in death or elec-  
trical shock.  
WARNING  
Electric Shock Hazard.  
Can cause injury or death.  
Foil‐faced insulation has conductive characteristics sim-  
ilar to metal. Be sure there are no electrical connections  
within a ½” of the insulation. If the foil‐faced insulation  
comes in contact with electrical voltage, the foil could  
provide a path for current to pass through to the outer  
metal cabinet. While the current produced may not be  
enough to trip existing electrical safety devices (e.g.  
fuses or circuit breakers), the current can be enough to  
cause an electric shock hazard that could cause person-  
al injury or death.  
CONNECT BLACK AND  
YELLOW WIRES TO  
FIELD-PROVIDED  
CONDUCTORS.  
CONNECT GROUND  
WIRE TO GROUND  
TERMINAL MARKED  
“GND”  
S
All field wiring must be done in accordance with  
National Electrical Code, applicable requirements of  
UL and local codes, where applicable.  
S
Electrical wiring, disconnect means and over-current  
protection are to be supplied by the installer. Refer to  
the air handler rating plate for maximum over-current  
protection, minimum circuit ampacity, as well as  
operating voltage.  
Figure 11. Making Electrical Connections  
208 VOLT CONVERSION  
1. Disconnect all power supplies.  
2. Remove the air handler access panel.  
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The power supply must be sized and protected  
according to the specifications supplied on the  
product.  
3. Using the wiring diagram located on the unit access  
panel as a reference, move the 2 connected black  
transformer leads from the 240 volt terminal on the  
transformer to the 208 volt terminal on the transformer.  
This air handler is factory-configured for 240 volt,  
single phase, 60 cycles. For 208-volt applications, see  
“208 Volt Conversion” later in this section.  
For optional field‐installed electric heat applications,  
refer to the instructions provided with the accessory  
for proper installation.  
WARNING  
Electrically ground air handler. Connect  
ground wire to ground terminal marked  
“GND”.  
WARNING  
USE COPPER CONDUCTORS ONLY  
Failure to do so can result in death or elec-  
trical shock.  
Page 9  
CBX25UH SERIES  
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THERMOSTAT  
AIR HANDLER  
THERMOSTAT  
AIR HANDLER  
R
G
R
G
BU  
W
SEE  
NOTE  
BU  
SEE  
NOTE  
Y
HEAT‐ONLY APPLICATION  
AIR  
CONDITIONER  
UNIT  
THERMOSTAT  
HEAT PUMP  
UNIT  
AIR HANDLER  
R
COOLING‐ONLY APPLICATION  
THERMOSTAT  
AIR HANDLER  
G
R
G
CONNECT COMMON  
WIRE ONLY IF  
REQUIRED  
BU  
(REFER TO THE  
APPROPRIATE  
THERMOSTAT  
INSTALLATION  
INSTRUCTIONS)  
W
BK  
W
BK  
SEE  
NOTE  
BU  
Y
HEAT PUMP APPLICATION WITH  
ELECTRIC HEAT  
AIR CONDITIONER  
UNIT  
COOLING APPLICATION WITH  
ELECTRIC HEAT  
NOTE - Connect common wire only if required (Refer to the appropriate thermostat installation instructions)  
Figure 12. Low Voltage Connections (3-Speed PSC Motor) - Field Wiring  
CHANGE BLOWER SPEED  
Airflow — Cooling Blower Speed  
1. Disconnect all power supplies.  
The cooling blower speed is factory configured to provide  
correct airflow for an outdoor unit that matches the cooling  
capacity rating of the air handler.  
2. Remove the air handler access panel.  
3. Locate pin number 2 on the blower relay. Two black  
wires are connected to this terminal pin. One connects  
to pin number 5 on the blower relay, one connects to  
an in-line splice connecting to a red wire.  
If the outdoor unit is smaller than the maximum cooling  
capacity rating for the air handler, the cooling blower speed  
may need to be changed. Refer to blower performance  
4. Remove the wire going to the 4-pin blower motor  
connector from the splice.  
WARNING  
Electric shock hazard! - Disconnect all  
power supplies before servicing.  
5. Connect the blower lead [Red (LO), Black (HI)] onto  
the splice from the 4-pin blower motor connector.  
NOTE — Reuse the factory-installed plastic cap on  
whichever wire is not used.  
Replace all parts and panels before op-  
erating.  
6. Replace all panels.  
7. Reconnect power.  
Failure to do so can result in death or elec-  
trical shock.  
Page 10  
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BLOWER RELAY  
CHANGING BLOWER SPEED  
PLASTIC CAPS  
5
BLOWER RELAY  
HARNESS  
BLUE (MED)  
RED (L0)  
2
BLACK (HI)  
YELLOW (COM)  
4-PIN  
BLOWER CONNECTOR  
Figure 13. Changing Blower Speed  
NOTE — Refer to wiring diagram located on the unit access panel (or figure 13 above) and blower performance (table 2).  
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All air data measured external to unit with 1 inch non-pleated air filter in place.  
All factory settings are medium speed except the -48 which is set to low speed from the factory.  
All data given while air handler is operating with a dry DX coil.  
Table 2. CBX25UH Blower Performance (3-Speed PSC) - 240V (CFM @ ESP. - in. W. C.)  
Air Handler  
Model  
Blower Speed  
.10” WC  
.20” WC  
.30” WC  
.40” WC  
.50” WC  
Low (Red)  
Med (Blue)  
High (Black)  
510  
670  
905  
495  
650  
865  
475  
630  
820  
420  
595  
770  
325  
505  
705  
18  
Low (Red)  
Med (Blue)  
High (Black)  
630  
885  
1130  
625  
875  
1100  
615  
850  
1070  
610  
820  
1010  
580  
780  
950  
24  
30  
36  
42  
48  
60  
Low (Red)  
Med (Blue)  
High (Black)  
900  
1075  
1240  
865  
1060  
1210  
830  
1030  
1170  
780  
985  
1135  
740  
940  
1085  
Low (Red)  
Med (Blue)  
High (Black)  
1160  
1500  
1660  
1140  
1445  
1575  
1115  
1385  
1495  
1085  
1300  
1405  
990  
1200  
1390  
Low (Red)  
Med (Blue)  
High (Black)  
1325  
1490  
1820  
1315  
1465  
1770  
1300  
1440  
1690  
1275  
1395  
1600  
1225  
1315  
1500  
Low (Red)  
Med (Blue)  
High (Black)  
1775  
1995  
2070  
1710  
1895  
1970  
1645  
1800  
1850  
1565  
1685  
1719  
1470  
1560  
1595  
Low (Red)  
Med (Blue)  
High (Black)  
1675  
1965  
2140  
1630  
1925  
2085  
1580  
1875  
2000  
1520  
1800  
1895  
1450  
1695  
1795  
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Blower Performance (CFM vs. ESP inches H2O)  
Cooling speeds should not be reduced below factory setting.  
Units with electric heat approved at 0.5” maximum and medium blower speed minimum.  
Page 11  
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Set the thermostat so that it does not call for heat.  
Allow up to 5 minutes for all sequencers to cycle off.  
Check-out Procedures  
NOTE - Refer to outdoor unit installation instructions for  
system start-up instructions and refrigerant charging  
instructions.  
Operation  
TIME DELAY RELAY  
Blower time delay operation:  
PRE‐START‐UP CHECKS  
1. When cooling demand is initiated, there is a 1 second  
motor-on delay.  
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Is the air handler properly and securely installed?  
If horizontally configured, is the unit sloped up to 5/8  
inch toward drain lines?  
2. After the motor-on delay expires, motor ramps up to  
100% and runs at 100% until cooling demand is  
satisfied.  
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Will the unit be accessible for servicing?  
Has an auxiliary pan been provided under the unit with  
separate drain for units installed above a finished  
ceiling or in any installation where condensate  
overflow could cause damage?  
3. Once demand is met, motor runs at 100% for 45  
seconds.  
4. Motor ramps down to stop.  
3
4
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Have ALL unused drain pan ports been properly  
plugged?  
100%  
CFM  
100%  
CFM  
2
1
Has the condensate line been properly sized, run,  
trapped, pitched, and tested?  
OFF  
1
SECOND  
DELAY  
COOLING  
DEMAND  
45  
SECS  
Is the duct system correctly sized, run, sealed, and  
insulated?  
Figure 14. Blower Time Delay  
COOLING (COOLING ONLY OR HEAT PUMP)  
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Have all cabinet openings and wiring been sealed?  
Is the indoor coil factory‐installed TXV properly sized  
for the outdoor unit being used?  
When the thermostat calls for cooling, 24 volts is put on the  
blower time-delay relay coil and then the indoor blower  
relay energizes. The normally open contacts close,  
causing the indoor blower motor to operate. The circuit  
between R and Y is completed, closing the circuit to the  
contactor in the outdoor unit, starting the compressor and  
outdoor fan motor.  
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Have all unused parts and packaging been disposed  
of?  
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Is the filter clean, in place, and of adequate size?  
Is the wiring neat, correct, and in accordance with the  
wiring diagram?  
On heat pumps, circuit R and O energizes the reversing  
valve, switching the valve to the cooling position. (The  
reversing valve remains energized as long as the  
thermostat selector switch is in the COOL position.)  
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Is the unit properly grounded and protected (fused)?  
Is the thermostat correctly wired and in a good  
location?  
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Are all access panels in place and secure?  
At the completion of the cooling demand the indoor blower  
and outdoor unit should cycle off. Air handler should cycle  
off 45 seconds after the outdoor unit shuts off.  
CHECK BLOWER OPERATION  
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Set thermostat to FAN ON.  
HEATING (ELECTRIC HEAT ONLY)  
The indoor blower should come on.  
When the thermostat calls for heat, the circuit between R  
and W is completed, and the heat sequencer is energized.  
A time delay follows before the heating elements and the  
indoor blower motor come on. Units with a second heat  
sequencer can be connected with the first sequencer to W  
on the thermostat subbase, or they may also be connected  
to a second stage on the subbase.  
CHECK COOLING OPERATION  
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Set thermostat to force  
a
call for cooling  
(approximately 5ºF lower than the indoor ambient  
temperature).  
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The outdoor and indoor units should come on  
immediately.  
HEATING (HEAT PUMP)  
Check the airflow from a register to confirm that the  
system is moving cooled air.  
When the thermostat calls for heating, 24 volts is put on the  
blower time-delay relay coil. Then normally open contacts  
close, causing the indoor blower motor to operate. The  
circuit between R and Y is completed, closing the circuit to  
the contactor in the outdoor unit, starting the compressor  
and outdoor fan motor.  
Set the thermostat 5ºF higher than the indoor  
temperature. The indoor blower and outdoor unit  
should cycle off. Air handler should cycle off 45  
seconds after the outdoor unit shuts off.  
CHECK ELECTRIC HEATER (IF USED)  
If the room temperature should continue to fall, the circuit  
between R and W1 is completed by the second‐stage heat  
room thermostat. Circuit R-W1 energizes a heat  
sequencer. The completed circuit will energize  
supplemental electric heat (if applicable). Units with a  
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Set thermostat to call for auxiliary heat (approximately  
5°F above ambient temperature). The indoor blower  
and auxiliary heat should come on together. Allow a  
minimum of 3 minutes for all sequencers to cycle on.  
Page 12  
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second heat sequencer can be connected with the first  
sequencer to W1 on the thermostat. They may also be  
connected to a second heating stage W2 on the  
thermostat subbase.  
Matt‐ or foil-faced insulation is installed in indoor  
equipment to provide a barrier between outside air  
conditions (surrounding ambient temperature and  
humidity) and the varying conditions inside the unit. If the  
insulation barrier is damaged (wet, ripped, torn or  
separated from the cabinet walls), the surrounding  
ambient air will affect the inside surface temperature of the  
cabinet. The temperature/humidity difference between the  
inside and outside of the cabinet can cause condensation  
on the inside or outside of the cabinet which leads to sheet  
metal corrosion and subsequently, component failure.  
EMERGENCY HEAT (HEATING HEAT PUMP)  
If the selector switch on the thermostat is set to the  
emergency heat position, the heat pump will be locked out  
of the heating circuit, and all heating will be electric heat (if  
applicable). A jumper should be placed between W2 and E  
on the thermostat subbase so that the electric heat control  
will transfer to the first‐stage heat on the thermostat. This  
will allow the indoor blower to cycle on and off with the  
electric heat when the fan switch is in the AUTO position.  
REPAIRING DAMAGED INSULATION  
Areas of condensation on the cabinet surface are an  
indication that the insulation is in need of repair.  
Maintenance  
IMPORTANT  
Do not operate system without a filter. A filter is required  
to protect the coil, blower, and internal parts from exces-  
sive dirt and dust. The filter is placed in the return duct  
by the installer.  
If the insulation in need of repair is otherwise in good  
condition, the insulation should be cut in an X pattern,  
peeled open, glued with an appropriate all-purpose glue  
and placed back against the cabinet surface, being careful  
to not overly compress the insulation so the insulation can  
retain its original thickness. If such repair is not possible,  
replace the insulation. If using foil‐faced insulation, any  
cut, tear, or separations in the insulation surface must be  
taped with a similar foil-faced tape.  
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Inspect air filters at least once a month and replace or  
clean as required. Dirty filters are the most common  
cause of inadequate heating or cooling performance.  
Replace disposable filters. Cleanable filters can be  
cleaned by soaking in mild detergent and rinsing with  
cold water.  
Install new/clean filters with the arrows on the side  
pointing in the direction of airflow. Do not replace a  
cleanable (high velocity) filter with a disposable (low  
velocity) filter unless return air system is properly sized  
for it.  
GLUE -make sure there is  
full coverage of glue on the  
metal or insulation so there  
are no areas where air  
pockets may form which  
can lead to sweating.  
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If water should start coming from the secondary drain  
line, a problem exists which should be investigated  
and corrected. Contact a qualified service technician.  
Cabinet Insulation  
1. CUT INSULATION IN X PATTERN  
2. APPLY GLUE  
3. PRESS GLUED TABS AGAINST CABINET  
IMPORTANT  
DAMAGED INSULATION MUST BE REPAIRED OR  
REPLACED before the unit is put back into operation. In-  
sulation loses its insulating value when wet, damaged,  
separated or torn.  
Figure 15. Repairing Insulation  
Page 13  
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Installing Contractor’s Name_______________________  
Installing Date_______________________________  
Installing Contractor’s Phone_______________________ Air Handler Model #___________________________  
Job Address____________________________________  
Thermostat  
9
Line Voltage  
3
SUPPLY  
AIR  
Disconnect  
Switch  
8
2
Integrated Control  
Temperature  
5
1
Duct  
System  
Blower Motor Amps  
Electric Heat Amps  
6
7
Duct Static  
RETURN  
AIR  
Filter  
4
Drain Line  
DUCT SYSTEM  
SUPPLY AIR DUCT  
Sealed  
TOTAL EXTERNAL STATIC (dry coil)  
dry coil wet coil  
5
1
Supply External Static ______  
Return External Static ______  
Total External Static = ______  
______  
______  
______  
Insulated (if necessary)  
Registers Open and Unobstructed  
RETURN AIR DUCT  
6
7
ELECTRIC HEAT AMPS____________  
INDOOR BLOWER AMPS___________  
INDOOR BLOWER CFM____________  
Sealed  
Filter Installed and Clean  
Registers Open and Unobstructed  
INTEGRATED CONTROL  
Jumpers Configured Correctly (if applicable)  
Appropriate Links in Place (if applicable)  
VOLTAGE CHECK  
TEMPERATURE DROP (Cooling Mode)  
Return Duct Temperature ___________  
8
2
3
Supply Duct Temperature ___________  
Temperature Drop = ___________  
8
TEMPERATURE RISE (Heating Mode)  
Return Duct Temperature __________  
Supply Duct Temperature __________  
Supply Voltage ___________  
Low Voltage _____________  
Electrial Connections Tight  
DRAIN LINE  
Temperature Rise = __________  
THERMOSTAT  
9
4
Adjusted and Programmed  
Leak Free  
Operation Explained to Owner  
Explained Operation of System to Homeowner  
Technician’s Name:_______________________Date StartUp & Performance Check Completed__________  
Figure 16. Start-Up and Performance Checklist (Upflow Configuration)  
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Installing Contractor’s Name_______________________  
Installing Date_______________________________  
Installing Contractor’s Phone_______________________ Air Handler Model #___________________________  
Job Address____________________________________  
Line Voltage  
Disconnect  
Switch  
Thermostat  
2
Integrated  
Control  
9
3
1
Duct System  
1
Duct System  
Filter  
RETURN  
SUPPLY  
AIR  
AIR  
Electric Heat Amps  
Blower motor Amps  
6
7
5
4
Drain Line  
8
Duct Static  
Temperature  
DUCT SYSTEM  
TOTAL EXTERNAL STATIC (dry coil)  
dry coil wet coil  
5
1
SUPPLY AIR DUCT  
Sealed  
Supply External Static ______  
Return External Static ______  
Total External Static = ______  
______  
______  
______  
Insulated (if necessary)  
Registers Open and Unobstructed  
RETURN AIR DUCT  
Sealed  
6
7
ELECTRIC HEAT AMPS____________  
INDOOR BLOWER AMPS___________  
INDOOR BLOWER CFM____________  
Filter Installed and Clean  
Registers Open and Unobstructed  
INTEGRATED CONTROL  
TEMPERATURE DROP (Cooling Mode)  
Return Duct Temperature ___________  
8
2
3
Supply Duct Temperature ___________  
Temperature Drop = ___________  
Jumpers Configured Correctly (if applicable)  
Appropriate Links in Place (if applicable)  
VOLTAGE CHECK  
8
TEMPERATURE RISE (Heating Mode)  
Return Duct Temperature __________  
Supply Duct Temperature __________  
Supply Voltage ___________  
Low Voltage _____________  
Electrial Connections Tight  
DRAIN LINE  
Temperature Rise = __________  
THERMOSTAT  
9
4
Adjusted and Programmed  
Leak Free  
Operation Explained to Owner  
Explained Operation of System to Homeowner  
Technician’s Name:_______________________Date StartUp & Performance Check Completed__________  
Figure 17. Start-Up and Performance Checklist (Horizontal Configuration)  
Page 15  
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