Lennox Merit CBX25UHV, CBX25UHV-018, CBX25UHV-036, CBX25UHV-048, CBX25UHV-024 Installation Instructions Manual
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INSTALLATION
©2018 Lennox Industries Inc.
Dallas, Texas, USA
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.
Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.
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.
INSTRUCTIONS
Merit® CBX25UHV (-10) Series
Units
AIR HANDLERS
507616-02
7/2018
Shipping and Packing List
Package 1 of 1 contains the following:
1 - Assembled air handler unit factory-equipped for up-flow or
horizontal air discharge application (includes up-flow 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.
General
The Merit® CBX25UHV air handler is designed for indoor
installation only. As shipped, the unit is ready for installation in
either up-flow or horizontal left-hand air discharge applications.
Horizontal drain pan may be repositioned in the field to allow
installation in the horizontal right-hand air discharge position.
Various accessories are listed in the CBX25UHV Product
Specification bulletin.
All units are equipped with a factory-installed check/expansion
valve.
Page 1
Merit® CBX25UHV Unit Dimensions – Up-flow – inches (mm)
NOTE - Unit is shipped configured for horizontal left-hand air discharge. Unit may be converted to horizontal right-
hand air discharge by repositioning horizontal drain pan.
Dimensions remain the same in all configurations.
Page 2
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.
Do not remove the cabinet knockouts until it has been
determined which knockouts will need to be removed for
the installation.
Select the 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 rating plate on the air handler for specific
information.
IMPORTANT
Merit® CBX25UHV units include a factory-installed
check/expansion valve which provides optimal refriger
ant control and system performance with outdoor units
of varying capacities. These units must be installed as
part of a matched system as outlined in the CBX25UHV
Product Specification bulletin.
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
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.
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.
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).
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.
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).
The air handler is shipped from the factory completely
assembled. This unit is provided with flanges for
connecting the supply plenum.
WARNING
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.
IMPORTANT
Excessive condensation may occur if the unit is installed
in a warm, humid place. When the unit is installed in an
unconditioned space, apply sealant around electrical
wires, refrigerant piping and condensate lines at the
point where they enter the cabinet.
Apply sealant on the inside of the cabinet at the point
where the electrical wires exit through the conduit open
ing. Sealing the cabinet in this way prevents warm,
moist, unconditioned air from entering the cabinet.
Warm, moist air in the cabinet forms condensate on the
cooler control box and electrical controls.
IMPORTANT
This unit is approved for installation clearance to com
bustible material as stated on the unit rating plate. Ac
cessibility and service clearances must take precedence
over combustible material clearances.
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.
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 Merit® CBX25UHV unit is installed in a closet with
a louvered return opening, the minimum open area for the
louvers will be:
● 320 square inches for -018 and -024 models;
● 360 square inches for -030 and -036 models;
● 450 square inches for -042 thru -060 models.
Page 3
MERIT® CBX25UHV SERIES
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.
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.
Installation
Each unit consists of a blower assembly, refrigerant coil
and controls in an insulated, galvanized steel factoryfinished enclosure. Knockouts are provided for electrical
wiring entrance.
For ease in installation, it is best to make any necessary
coil configuration changes before setting air handler in
place.
REFRIGERANT METERING DEVICE
CBX25UHV units are equipped with a check/expansion
valve, which is factory-installed internal to the cabinet.
UP-FLOW APPLICATION
1 - The air handler must be supported on the bottom only
and set on a solid floor or a field‐supplied support
frame. Securely attach the air handler to the floor or
support frame.
2 - If installing a unit in an up-flow application, remove the
horizontal drain pan.
IMPORTANT - The horizontal drain pan is not required in
up-flow air discharge installations. It must be removed
to provide the best efficiency and air flow.
3 - Place the unit in the desired location and properly
slope the unit (see page 8). Connect the return and
supply air plenums as required using sheet metal
screws.
4 - In applications that do not include a return air plenum,
install units on a stand that is raised at least 14” above
the floor. This ensures proper air return.
HORIZONTAL APPLICATIONS
IMPORTANT
When removing the coil, there is a possibility of equip
ment damage and personal injury. Be careful when re
moving 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 re
moving it.
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.
LEFT-HAND DISCHARGE
1 - Determine which plugs are required for drain line
connections.
2 - With access door removed, remove drain line plugs to
install drain lines.
3 - Set unit so that it is sloped toward the end of the unit with
the drain pan (see figure 14).
4 - A typical horizontal configuration is shown in figure 2.
AIR FLOW
Drains
PLUGS
Figure 2. Left‐Hand Discharge Configuration
LEFT‐HAND DRAINS
HORIZONTAL DRAIN PAN
IMPORTANT - REMOVE PAN
FOR BEST EFFICIENCY
AND AIR FLOW.
UP-FLOW
DRAIN PAN
UP-FLOW DRAIN
CONNECTIONS (BOTH
SIDES; USE ONE SIDE
OR OTHER)
Figure 1. Up-flow Configuration
HORIZONTAL DRAIN
CONNECTIONS
(BOTH SIDES; NOT
USED)
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
to avoid damaging the coil or filter. See figure 3. 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 unit from the air handler.
ANGLE IRON OR SHEET METAL ELECTRICAL INLET CLEAR
MAXIMUM 1/2”
LONG SCREW
AIR FLOW
FRONT VIEW END VIEW
ANCE 4 IN. (102 MM)
Figure 3. Suspending Horizontal Unit
RIGHT-HAND AIR DISCHARGE
For horizontal right-hand air discharge, the following field
modifications are required.
1 - Remove and set aside blower and coil access panels.
2 - Remove brackets securing pans to unit. See figure 4.
Figure 5. Remove Coil Assembly, Bottom Drain Pan
and Horizontal Drain Pan As A Unit
Figure 4. Remove Main Drain Pan Mounting
Brackets
4 - Remove the blow-off prevention brackets, top cap and
drip pan between slabs. Move the horizontal drain pan
to the opposite side of the coil.
Figure 6. Remove Blow-Off Prevention Brackets,
Top Cap and Drip Pan
5 - Rotate drip pan 180º and reinstall on coil as shown by
the arrow above. Reinstall the top cap. Rotate the
blow-off prevention brackets 180º and reinstall using
the same screws. Use the correct mounting holes; the
brackets must cover the hairpins. See figure 7.
Page 5
MERIT® CBX25UHV SERIES
Figure 7. Reinstall the Top Cap. Brackets Must
Cover the Hairpins
6 - Slide coil assembly, bottom drain pan and horizontal
drain pan as one unit back into the air handler.
Figure 9. Reinstall Brackets that Hold the Coil and
Horizontal Drain Pan in Place
Repositioning Black Box on Motor Module – -018,
-024 and -030 Units
When the horizontal drain pan is moved to the right side of
the air handler, the black box on the back of the supply fan
motor will prevent the insertion of the blower assembly
back into the cabinet. The black box must be repositioned
to overcome this issue.
Tools and Material Required:
1" or 2" putty knife and 1" wide double-sided tape.
8 - Arrange the blower assembly on a stable surface with
the motor facing up.
MOTOR
MODULE
Figure 8. Slide Coil Assembly, Bottom Drain Pan
and Horizontal Drain Pan Back Into the Air Handler
as a Unit
7 - Reinstall the brackets that hold the coil and horizontal
drain pan in place. See figure 9.
BLACK
BOX
Figure 10. Black Box in Factory Position on Motor
Module
Page 6
9 - The black box is fastened to the motor module at each
end with a strip of black double-sided tape. Starting at
one end, slide the putty knife between the black box
and the motor module. Carefully separate the black
box from the motor module. Clean off any
double-sided tape remaining on the motor module.
Figure 11. Black Box Separated from Motor Module
11 - Slide the blower assembly into the cabinet to confirm
clearance between the horizontal drain pan and the
black box. Remove the blower assembly and relocate
the black box if necessary to achieve clearance. Make
note of the new position. Apply two new strips of
double-sided tape to the black box and affix it to the
module in the confirmed position.
12 -Slide the blower assembly back into the air handler
cabinet and install the two screws to secure the
assembly to the cabinet. Plug the motor wires back
into the motor and black box.
13 -Confirm that the black box is not touching the
horizontal drain pan.
10 - Cut a small piece of tape and apply it to the back of the
black box. This will be used to test the position of the
black box. The goal is to raise the position of the box
on the module. Position the black box onto the module
higher than the original position.
Figure 12. Black Box Repositioned on Motor Module
Figure 13. Blower Assembly Installed in Air Handler
Cabinet with Required Clearance Between
Horizontal Drain Pan and Motor Black Box
Page 7
MERIT® CBX25UHV SERIES
Condensate Drain
IMPORTANT
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.
The air handler is provided with ¾” NPT condensate drain
connections.
SLOPING THE UNIT
Make sure the unit is sloped (similar to the slope shown in
figure 14) (horizontal or up-flow) so that the drain pan will
empty completely without water standing in the pan.
THIS CORNER SHOULD BE 5/8” (+/- 1/8”) HIGHER
THAN DRAIN CORNER
THIS CORNER SHOULD BE
5/8” (+/- 1/8”) HIGHER THAN
DRAIN CORNER
INSTALL CONDENSATE DRAIN
The air handler is equipped with ¾” NPT condensate drain
connections.
IMPORTANT
On some pans, the primary and secondary drain holes
have knockouts.
Confirm primary and secondary drains are open.
1 - CB25UHV units are equipped with a drain pan, which
includes green (main drain) and red (secondary drain)
plugs. Unscrew the plugs to remove them before
inserting condensate drain fittings.
ALL CBX25UHV MODELS
UNSCREW PLUGS
AND CONNECT
PROPERLY SIZED
FIELD-PROVIDED
FITTINGS AND
DRAIN LINES.
DRAIN PAN
GREEN MAIN
DRAIN PLUG
RED SECONDARY
DRAIN PLUG
DRAIN CORNER
Figure 14. Sloping the Unit for Proper Drainage
Figure 15. Drain Line Connections
Page 8
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