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
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*
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
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
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
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
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
illustrated in figures 4 and 5.
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
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
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
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
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
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.
S
S
S
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
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
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).
S
S
S
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
S
S
S
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
CBX25UH SERIES
S
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.
S
S
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.
S
S
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
S
S
S
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)
S
S
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.
S
Have all unused parts and packaging been disposed
of?
S
S
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.)
S
S
Is the unit properly grounded and protected (fused)?
Is the thermostat correctly wired and in a good
location?
S
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
S
S
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
S
Set thermostat to force
a
call for cooling
(approximately 5ºF lower than the indoor ambient
temperature).
S
S
S
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
S
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
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.
S
S
S
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.
S
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
CBX25UH SERIES
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 Start−Up & Performance Check Completed__________
Figure 16. Start-Up and Performance Checklist (Upflow Configuration)
Page 14
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 Start−Up & Performance Check Completed__________
Figure 17. Start-Up and Performance Checklist (Horizontal Configuration)
Page 15
CBX25UH SERIES
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