Lennox CB26UH series User manual

07/11 505,059M (65937170)
*2P0711* *P505059M*
Page 1
E2011 Lennox Industries Inc.
Dallas, Texas, USA
TXV RFC
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a qualified installer or service agency.
CAUTION
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.
IMPORTANT
The Clean Air Act of 1990 bans the intentional venting of
refrigerant (CFCs and 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.
IMPORTANT
This unit must be matched with an outdoor unit as spe-
cified in Lennox Engineering Handbook.
INSTALLATION
INSTRUCTIONS
CB(X)26UH(−R) Series Units
AIR HANDLERS
505,059M (65937170)
07/11
Supersedes 05/11
Table of Contents
Shipping and Packing List 1. . . . . . . . . . . . . . . . . . . . . .
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CB(X)26UH Series Units 3. . . . . . . . . . . . . . . . . . . . . . .
Requirements 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation Clearances 4. . . . . . . . . . . . . . . . . . . . . . . . .
Installation 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Condensate Drain 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System and Filters 8. . . . . . . . . . . . . . . . . . . . . . . .
Connecting Refrigerant Lines 9. . . . . . . . . . . . . . . . . . .
Sealing the Unit 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Connections 9. . . . . . . . . . . . . . . . . . . . . . . . .
Airflow − Cooling Blower Speed 12. . . . . . . . . . . . . . . . . .
Check−Out Procedures 15. . . . . . . . . . . . . . . . . . . . . . . . .
Operation 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cabinet Insulation 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List
Package 1 of 1 contains the following:
1 − Assembled air handler unit for upflow or horizontal air
discharge application (includes upflow and horizontal
drain pans)
NOTE  For downflow application, order kit 12W61
(0658731−75).
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.
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during installa-
tion, maintenance, or repair will expose you to fiberglass
wool. Breathing this may cause lung cancer. (Fiberglass
wool is known to the State of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin, and
eye irritation.
To reduce exposure to this substance or for further infor-
mation, consult material safety data sheets available
from address shown below, or contact your supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
Litho U.S.A.

Page 2
505059M 0511
CB(X)26UH Unit Dimensions − inches (mm)
A
BC
D
E
F
FRONT VIEW SIDE VIEW
LINE VOLTAGE RIGHT,
LEFT AND TOP
LOW VOLTAGE
RIGHT SIDE ONLY
SUCTION
LINE
LIQUID
LINE
FILTER ACCESS
CONDENSATE DRAIN
PIPING PLATE (4) (2−1/4 X 3−3/4)
1 (25)
AIR FLOW
H
2-1/2 (64)
2-1/2 (64) 1-1/2 (38)
1-1/2 (38)
(OPENING) (OPENING)
OPTIONAL DUCT ADAPTOR KIT (KIT ALLOWS DIRECT
CONNECTION OF THE DUCTWORK TO THE RETURN AIR
OPENING OF THE AIR HANDLER, NOT REQUIRED IF AN
EXTERNAL FILTER IS USED.)
G
3/4 (19)
CB(X)26UH Dimensions (for Upflow and LH/RH Horizontal Air Discharge Applications)
Dimension
−018, −024 −030, −036 −037*, −042, −048* −060
inches mm inches mm inches mm inches mm
A46−3/4 1187 51 1295 54 1372 60 1524
B18−1/2 470 21−1/4 540 21-1/4 540 21-1/4 540
C22 559 22 559 26 660 26 660
D11 279 12−1/2 318 12 305 11−3/4 298
E16 406 18−1/2 470 16−3/4 425 17 432
F5−1/2 140 6 152 4 102 4 102
G13−1/2 343 16 406 16 406 16 406
H19 483 19 483 23 584 23 584
Supply Air
Opening
Depth 17 432 17 432 21 533 21 533
Width 16−1/2 419 19−1/4 489 19−1/4 489 19−1/4 489
Return Air
Opening
Depth 18−1/4 464 18−1/4 464 22−1/4 565 22−1/4 565
Width 13−1/2 343 16−1/4 413 16−1/4 413 16−1/4 413
* −037 and −048 units not available in RFC model.

Page 3
CB(X)26UH SERIES
CB(X)26UH Series Air Handlers
All CB(X)26UH air handlers are designed for indoor
installation only. As shipped, the units are ready for
installation in either upflow or horizontal left−hand air
discharge applications. All units may be installed with
optional field−installed electric heat and a matched remote
outdoor unit.
SCBX26UH air handlers may be installed with a
matched HFC−410A remote outdoor unit. These units
are completely assembled, including a factory
installed check/expansion valve.
SCB26UH air handlers may be installed with a matched
HCFC−22 remote outdoor unit. These units are
completely assembled, including a factory installed
check/expansion valve.
Table 1. Orifice (RFC) Part Number (Sizes − in.)
Model
HCFC−22 NOTE 1HFC−410A NOTE 2
13HPD / HP13 XC13 / XP13
018 100484−08 (0.057)
Refer to orifice table in
outdoor unit installation
manual
024 100484−11 (0.061)
030 100484−21 (0.072)
036 100484−23 (0.074)
042 100484−30 (0.082)
037, 048 not supported
060 100484−44 (0.098)
Note 1 − Orifice ships
with Air Handler.
Note 2 − Orifice ships with
outdoor units.
SCB26UH−R (RFC) units may be installed with a
matched remote 13HPD/ HP13 outdoor unit. These
units are equipped with an HCFC−22 refrigerant flow
control device (see orifice table 1). Also, these units
can be used with HCFC−22 (13ACD/AC13), or
HFC−410A refrigerant provided the RFC shipped with
the outdoor unit is installed in place of the RFC device
shipped with the CB26UH−R unit.
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.
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).
IMPORTANT
The CB(X)26UH 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)
or refrigerant flow control (RFC) device to provide opti-
mum refrigerant control and system performance with a
variety of different capacities of outdoor units.
TXV unitsIn some cases, the rating of the outdoor unit
may require that the coil assembly installed TXV be
changed to obtain rated performance.
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 (not
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. The unit is provided with flanges for the
connection of the duct system.
Do not remove the cabinet knockouts until it has been
determined which knockouts will need to be removed for
the installation.
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.
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.
NOTES 
During cooling operation, excessive sweating may occur if
the air handler is installed in a very 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.
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.

Page 4
505059M 0511
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.
The air handler must be installed so that free access is
allowed to the coil/filter compartment and blower/control
compartment.
Horizontal applications of the air handler must be installed
sloped (approximately 5/8 inch) toward the drain pan
openings to ensure proper condensate drainage.
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 CB(X)26UH unit is installed in a closet with a
louvered return opening, the minimum open area for the
louvers will be:
S320 square inches for −018 and −024 models;
S360 square inches for −030 and −036 models;
S450 square inches for −042 thru −060 models.
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
GENERAL INFORMATION
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal inju-
ry or loss of life. Installation and service must be per-
formed by a qualified installer or service agency.
CB(X)26UH units are factory−assembled and configured
for installation in upflow or horizontal left−hand air
discharge applications.
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.
For ease in installation, it is best to make any necessary
coil configuration changes before setting air handler in
place.
If a filter is to be installed at the air handler, early models
require a filter rack be formed using factory−supplied
flanges. Lay the unit on its back and pry out the filter rack
tabs as shown in figure 1. Repeat procedure on opposite
side.
Figure 1. Filter Rack Tabs (Pre April 2006)
Later models are equipped with rails in which the filter
slides. Two screws and a bracket must be removed to
insert and remove the filter (see figure 2).
FILTER RAILS
SCREWS
BRACKET (DUCT ADAPTER AND
SELF TAPPING SCREWS
− OPTIONAL FOR AT-
TACHING RETURN AIR
DUCT)
Figure 2. Filter Rails (April 2006 and Later)
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.
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.
3. Place the unit in the desired location and level it.
Connect return and supply air plenums as required
using sheet metal screws.

Page 5
CB(X)26UH SERIES
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.
HORIZONTAL DRAIN PAN
IMPORTANT! REMOVE PAN
FOR BEST EFFICIENCY
AND AIR FLOW.
UPFLOW
DRAIN PAN
UPFLOW DRAIN CON-
NECTIONS (BOTH
SIDES; USE ONE SIDE
OR OTHER)
HORIZONTAL DRAIN
CONNECTIONS
(BOTH SIDES; NOT
USED)
Figure 3. Upflow Configuration
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.
FRONT VIEW END VIEW
ANGLE IRON OR SHEET
METAL
ELECTRICAL INLET CLEAR-
ANCE 4 IN. (102 MM)
1/2 IN. SCREWS
MAX.
AIR FLOW
Figure 4. Suspending Horizontal Unit
NOTE  When the unit is installed in horizontal
applications, a secondary drain pan is recommended.
Refer to local codes.
NOTE  For applications where return air ducting is to be
connected to the bottom of the coil blower, Lennox offers a
duct adapter kit which mounts on the filter door side of the
end of the unit (shown in figure 2). This provides a metal
edge for attaching the return air duct. One duct adapter
and two self−tapping screws are needed for each
installation. Packages of 10 adapters/20 screws are
available: 0658731−85 (Catalog No. X8103) for the
−018/−024 size units; 0658731−86 (Catalog No. X8104) for
the −030 to −060 size units.
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.
1. Determine whether left-hand or right-hand air
discharge is required. If right-hand is required, perform
Right−Hand Discharge Modification on page 6.
2. Determine knockouts required for drain line
connections.
3. With access door removed, knock out drain line
opening for installing drain lines.
4. Set unit so that it is sloped toward the drain pan end of
the unit (see figure 10 on page 7).
5. The horizontal configuration is shown in figure 5.
6. 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 4. Use
sheet metal screws to connect the return and supply
air plenums as required.
Drains
AIR FLOW
KNOCKOUT LEFT-HAND DRAINS
Figure 5. Left-Hand Discharge Configuration
RIGHT−HAND AIR DISCHARGE MODIFICATION
For horizontal right−hand air discharge, the following field
modifications are required.
1. Remove and set aside blower and coil access covers.
2. Remove the coil support bracket (detail A, figure 7).
3. Remove coil assembly, bottom drain pan and
horizontal drain pan as one assembly from the air
handler.
4. Remove two screws, blow off prevention bracket
(where used; see table 2), and horizontal drip shield.
Rotate the brackets 180º and reinstall using the same
screws.
5. Move the horizontal drain pan to the opposite side of
the coil. Be sure drain holes toward the back of the unit
are plugged (see figure 8). Remove the plugs from the
front drain pan ports.
6. Re−install modified coil/drain pan assembly in air
handler in the same orientation as before.

Page 6
505059M 0511
7. Install the coil support bracket on the opposite side of
the air handler (figure 7, detail B).
RIGHT-HAND DRAINS
KNOCKOUT
Drains
AIR FLOW
Figure 6. Right-Hand Discharge Configuration
Table 2. Blow Off Prevention Bracket
Model Front Rear
−018 None None
−024 None None
−030 Yes Ye s
−036 Yes Ye s
−037 None None
−042 None None
−048* Yes None
−060 Yes None
* −048 model supported in TXV units only.
REMOVE DRAIN PAN FROM HERE
THEN...
DETAIL A
BRACKET SHOWN AS SHIPPED
BRACKET SHOWN FOR RIGHT HAND DISCHARGE
DETAIL B
REMOVE COIL SUPPORT BRACKET FROM HERE
THEN...
ROTATE SHIELD AND BRACKET AND REINSTALL
REMOVE 2 SCREWS, BLOW OFF PREVENTION
BRACKET(S), AND DRIP SHIELD FROM HERE
THEN...
REINSTALL PAN HERE
REINSTALL BRACKET HERE
NOTE − EXPANSION VALVE SHOWN ON
COIL IS NOT ON CB26UH−R (RFC)
EQUIPPED UNITS.
Figure 7. Field Modification for Right−Hand Discharge
OPEN END FOR CONDENSATION
DRAIN
COIL ASSEMBLY
PLUGGED
END
Figure 8. Right-Hand Drain Plug Location
REFRIGERANT METERING DEVICE
NOTE  See the outdoor unit installation instructions and
the Lennox Engineering Handbook for approved fixed
orifice match−ups and application information.
CB26UH−R units are equipped with a factory−installed
refrigerant flow control (RFC) device (see table 1 on
Page 3).
IMPORTANT
If a unit equipped with an RFC device is used in an ap-
plication which requires conversion to an expansion
valve, the fixed orifice must be removed before the ex-
pansion valve is installed.

Page 7
CB(X)26UH SERIES
The coil has a fixed orifice in the liquid line (see figure 9).
Remove the rubber plug from the vapor line of the coil.
STRAINER
LIQUID LINE STUB
DISTRIBUTOR
O−RING FIXED ORIFICE
Figure 9. Metering Device Installation
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 condensate drain lines (primary and auxiliary, if
used). Traps prevent the blower from drawing air through
the drain lines into the air supply.
IMPORTANT
A field−fabricated secondary drain pan, with a drain pipe
to the outside of the building, is required in all installations
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 an secondary drain
pan for any horizontal installation.
The air handler is provided with ¾" NPT condensate drain
connections.
SLOPING THE DRAIN
Make sure the unit is sloped (similar to the slope shown in
figure 10) 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
DRAIN CORNER
THIS CORNER SHOULD BE
5/8" (+/− 1/8") HIGHER THAN
DRAIN CORNER
Figure 10. Sloping the Drain
INSTALL CONDENSATE DRAIN
1. Remove the appropriate drain knockouts. If
necessary, remove the indoor coil assembly from the
cabinet.
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.
NOTE  When making drain fitting connections to the
drain pan, hand tighten the fitting and use a sealant.
Over−tightening the fittings can split connections on the
drain pan.
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.
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.
5. Make sure drain ports and drain pan are free of all
debris.
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.
7. Install a 2" trap in the primary drain lines as close to the
unit as practical (see figure 11). Make sure the top of
the trap is below the connection to the drain pan to
allow complete drainage of the pan.
NOTE  Horizontal runs must have an anti−siphon air vent
(standpipe) installed ahead of the horizontal run (See
figure 11). An extremely long horizontal run may require an
oversized drain line to eliminate air trapping.
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.
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.
NOTE  Check local codes before connecting the drain
line to an existing drainage system.
Insulate the drain lines where sweating could cause water
damage.

Page 8
505059M 0511
ABOVE
FINISHED
SPACE?
OVERFLOW DRAIN LINE
ALWAYS RUN AN OVERFLOW DRAIN LINE. IF NOT POSSIBLE TO
ROUTE OVERFLOW DRAIN LINE, INSTALL LOW VOLTAGE
OVERFLOW SWITCH KIT. WIRE KIT TO SHUT DOWN
COMPRESSOR PER INSTRUCTIONS.
NO
YES
LENNOX #
X3169 CLEAN OUT
VENT
PRESS IN
(DO NOT GLUE)
VENT MUST EXTEND
ABOVE HEIGHT OF
COIL DRAIN PAN BY
TWO INCHES (51MM)
1" X 3/4" X 3/4"
REDUCING
TEE WITH
PLUG
LENNOX* P−TRAP
49P66, J−TRAP #
91P90 OR ANY
PVC SCH 40 P− OR
J−TRAP 3/4"
OVERFLOW
DRAIN
OPTIONAL
SAFETY
PAN
AIR HANDLER DRAIN PAN
WHEN A COIL IS LOCATED ABOVE A FINISHED SPACE, A 3/4" (19.1MM) SECONDARY DRAIN
LINE MUST BE:
SCONNECTED TO SECONDARY DRAIN PAN
OR
SCONNECTED TO THE OVERFLOW DRAIN OUTLET OF THE AIR HANDLER DRAIN PAN.
PRIMARY AND SECONDARY TRAPS MUST BE DEEP ENOUGH TO OFFSET MAXIMUM STATIC
DIFFERENCES  GENERALLY, TWO INCHES (51MM).
DRAIN LINE SHOULD
SLOPE A MINIMUM OF
ONE INCH PER 10
FEET (25MM PER 3
METERS)
NOTE  WHEN A AIR HANDLER IS LOCATED ABOVE A FINISHED SPACE THE SECONDARY
DRAIN PAN MUST HAVE A LARGER FOOTPRINT THAN THE AIR HANDLER.
MAIN
DRAIN
TO APPROVED
DRAIN
FOR NEGATIVE PRESSURE COILS (BLOWER
AFTER COIL) TRAPS ARE REQUIRED ON ALL
DRAIN LINES CONNECTED TO COIL.
COMPACT OVERFLOW SWITCH WITH 3/4" FEMALE SLIP INLET
AND MALE ADAPTER, TWO PART DESIGN FOR USE WHERE
OBSTRUCTIONS PREVENT DIRECT THREADING
SECONDARY
DRAIN PAN
2"
(51MM)
TRAP DEPTH
*LENNOX P−TRAP 49P66 REQUIRES A LARGER INSTALLATION SPACE THAN THE J−TRAP 91P90.
Figure 11. Typical Main and Overflow Drain
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.
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.
3. Correct any leaks found.
Duct System and Filters
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.
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.
Table 3. Unit Air Filter Size Chart
Model Filter Size
−018 / −024 15" x 20" (Effective 22 Mar 11)
−030 / −036 18" x 20"
−037 through −060 18" x 25"
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.
INSTALLING DUCT SYSTEM
Install the conditioned air plenum, ducts and air filters (not
provided) in accordance with NFPA 90B Standard for the
Installation of Warm Air Heating and Air−Conditioning
Systems (latest edition).
Connect supply air duct to the flange on top of the air
handler. If an isolation connector is used, it must be
nonflammable.

Page 9
CB(X)26UH SERIES
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Electrical Connections
WARNING
Electric shock hazard! − Disconnect all
power supplies before servicing.
Replace all parts and panels before
operating.
Failure to do so can result in death or
electrical 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.
SAll field wiring must be done in accordance with
National Electrical Code, applicable requirements of
UL and local codes, where applicable.
SElectrical 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

Page 10
505059M 0511
protection, minimum circuit ampacity, as well as
operating voltage.
SThe power supply must be sized and protected
according to the specifications supplied on the
product.
SThis air handler is factory−configured for 240 volt,
single phase, 60 cycles. For 208−volt applications, see
208 Volt Conversion" later in this section.
SFor optional field-installed electric heat applications,
refer to the instructions provided with the accessory
for proper installation.
WARNING
USE COPPER CONDUCTORS ONLY
1. Disconnect all power supplies.
2. Remove the air handler access panel.
3. Route the field supply wires to the air handler electrical
connection box.
WARNING
Electrically ground air handler. Connect
ground wire to ground terminal marked
GND".
Failure to do so can result in death or elec-
trical shock.
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."
5. Replace the air handler access panel.
GND
CONNECT BLACK
TO BLACK
CONNECT UNIT ’S
YELLOW CONDUC-
TOR TO WHITE
FIELD SUPPLY
CONDUCTOR
CONNECT
GROUND WIRE TO
GROUND TERMI-
NAL MARKED GND"
Figure 12. Making Electrical Connections
208 VOLT CONVERSION
WARNING
Electric shock hazard! − Disconnect all
power supplies before servicing.
Replace all parts and panels before op-
erating. Failure to do so can result in death
or electrical shock.
1. Disconnect all power supplies.
2. Remove the air handler access panel.
3. Using the wiring diagram in figure 13 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.

Page 11
CB(X)26UH SERIES
WARNING
USE COPPER
CONDUCTORS
ONLY
Figure 13. Wiring Diagram

Page 12
505059M 0511
R
G
CONDENSING
UNIT
R
R
R
G
G
G
BU
BU
W
W
W
BK
BK
COOLING-ONLY APPLICATION
AIR HANDLERTHERMOSTAT
HEAT-ONLY APPLICATION
AIR HANDLERTHERMOSTAT
CONDENSING
UNIT
COOLING APPLICATION WITH
ELECTRIC HEAT
AIR HANDLERTHERMOSTAT
HEAT PUMP APPLICATION WITH ELECTRIC HEAT
AIR HANDLERTHERMOSTAT HEAT PUMP UNIT
NOTE − Connect common wire only if required (Refer to the appropriate thermostat installation instructions)
BU
BU
SEE
NOTE
SEE
NOTE
SEE
NOTE
SEE
NOTE
Figure 14. Low Voltage Connections
Airflow  Cooling Blower Speed
The cooling blower speed is factory configured to provide
correct airflow for an outdoor unit that matches the
maximum cooling capacity rating of the air handler.
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
Chart, table 4.
CHANGE BLOWER SPEED
NOTE  Refer to wiring diagram (figure 13) and blower
performance (table 4).
WARNING
Electric shock hazard! − Disconnect all
power supplies before servicing.
Replace all parts and panels before op-
erating.
Failure to do so can result in death or elec-
trical shock.
1. Disconnect all power supplies.
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.
4. Remove the wire going to the 4−pin blower motor
connector from the splice.
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.
6. Replace all panels.
7. Reconnect power.
NOTES FOR TABLE 4 − All air data measured external to unit with 1
inch non−pleated air filter in place.
Electric heaters have no appreciable air resistance.
All factory settings are high−speed.
All data given while air handler is operating with a dry dx coil.

Page 13
CB(X)26UH SERIES
Table 4. CB(X)26UH Blower Performance (2−Speed)
Model External Static Pressure Air Volume at Specific Blower Taps
High (Black) Low (Red)
in. w.g. Pa cfm L/s cfm L/s
−018
(LOW SPEED)
.10 25 1020 460 755 340
.20 50 960 435 715 325
.30 75 885 400 675 305
.40 100 800 365 625 285
.50 125 690 315 570 260
.60 150 525 250 500 235
−024
(MEDIUM
SPEED)
.10 25 1040 470 1000 455
.20 50 980 445 940 425
.30 75 905 410 870 395
.40 100 815 370 785 355
.50 125 705 320 680 310
.60 150 535 250 530 250
−030
(MEDIUM
SPEED)
.10 25 1350 610 1145 520
.20 50 1290 585 1090 495
.30 75 1225 555 1030 465
.40 100 1150 520 960 435
.50 125 1065 485 875 395
.60 150 965 455 775 365
−036
(LOW SPEED)
.10 25 1560 705 1405 635
.20 50 1480 670 1340 610
.30 75 1390 630 1270 575
.40 100 1290 585 1185 540
.50 125 1170 530 1090 495
.60 150 1015 480 975 460
−037
(LOW SPEED)
.10 25 1570 740 1330 625
.20 50 1520 715 1310 620
.30 75 1440 680 1250 590
.40 100 1300 615 1180 555
.50 125 1170 550 1070 505
.60 150 950 450 840 395
−042
(MEDIUM
SPEED)
.10 25 1940 880 1785 810
.20 50 1845 835 1705 775
.30 75 1745 790 1615 730
.40 100 1630 740 1515 685
.50 125 1495 680 1400 635
.60 150 1330 630 1265 595
−048
(supported in
TXV only)
(MEDIUM
SPEED)
.10 25 1945 880 1870 850
.20 50 1860 845 1790 810
.30 75 1765 800 1700 770
.40 100 1660 155 1600 725
.50 125 1540 700 1485 675
.60 150 1395 660 1350 635
−060
(MEDIUM
SPEED)
.10 25 2160 980 2075 940
.20 50 2065 935 1985 900
.30 75 1960 890 1885 855
.40 100 1845 835 1775 805
.50 125 1710 775 1645 745
.60 150 1550 730 1495 705

Page 14
505059M 0511
Table 5. CB(X)26UH Blower Performance (3−Speed)
Model Ext. Static Pressure Air Volume at Specific Blower Taps
Low (Red) Med (Blue) High (Black)
in. w.g. Pa cfm L/s cfm L/s cfm L/s
−018
(LOW SPEED)
0.10 25 655 309 794 375 1074 507
0.20 50 647 305 786 371 1000 472
0.30 75 628 296 747 353 913 431
0.40 100 578 273 672 317 809 382
0.50 125 480 227 555 262 672 317
0.60 150
−024
(MEDIUM
SPEED)
0.10 25 655 309 794 375 1074 507
0.20 50 647 305 786 371 1000 472
0.30 75 628 296 747 353 913 431
0.40 100 578 273 672 317 809 382
0.50 125 480 227 555 262 672 317
0.60 150
−030
(MEDIUM
SPEED)
0.10 25 860 406 1020 481 1199 566
0.20 50 851 402 1006 475 1195 564
0.30 75 842 397 1003 473 1182 558
0.40 100 813 384 963 454 1121 529
0.50 125 721 340 886 418 1033 487
0.60 150
−036
(LOW SPEED)
0.10 25 1135 536 1354 639 1494 705
0.20 50 1120 529 1345 635 1469 693
0.30 75 1112 525 1317 621 1417 669
0.40 100 1079 509 1260 595 1336 630
0.50 125 995 470 1090 514 1250 590
0.60 150
−042
(MEDIUM
SPEED)
0.10 25 1202 567 1404 663 1540 727
0.20 50 1192 563 1413 667 1530 722
0.30 75 1160 547 1386 654 1507 711
0.40 100 1116 527 1303 615 1386 654
0.50 125 998 471 1192 563 1254 592
0.60 150
−048
(MEDIUM
SPEED)
0.10 25 1593 752 1759 830 1886 890
0.20 50 1582 747 1709 806 1820 859
0.30 75 1526 720 1636 772 1742 822
0.40 100 1444 681 1538 726 1606 758
0.50 125 1318 622 1395 658 1446 682
0.60 150
−060
(MEDIUM
SPEED)
0.10 25 1782 841 2066 975 2109 995
0.20 50 1755 828 1960 925 2067 975
0.30 75 1672 789 1860 878 1949 920
0.40 100 1554 733 1714 809 1770 835
0.50 125 1393 657 1476 697 1586 748
0.60 150

Page 15
CB(X)26UH SERIES
Check−out Procedures
IMPORTANT
During installation, service or maintenance, make sure
that copper tubing does not rub against metal edges or
other copper tubing. Care should also be taken to ensure
that tubing does not become kinked. Use wire ties to se-
cure tubing to prevent movement.
Do not secure electrical wires to tubing that carries hot
refrigerant gas. Heat from the tubing may melt the wiring
insulation causing a short circuit.
NOTE − Refer to outdoor unit installation instructions for
system start−up instructions and refrigerant charging
instructions.
PRE-START-UP CHECKS
SIs the air handler properly and securely installed?
SIf horizontally configured, is the unit sloped up to 1/4
inch toward drain lines?
SWill the unit be accessible for servicing?
SHas 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?
SHave ALL unused drain pan ports been properly
plugged?
SHas the condensate line been properly sized, run,
trapped, pitched, and tested?
SIs the duct system correctly sized, run, sealed, and
insulated?
SHave all cabinet openings and wiring been sealed?
SIs the indoor coil factory-installed TXV properly sized
for the outdoor unit being used?
SHave all unused parts and packaging been disposed
of?
SIs the filter clean, in place, and of adequate size?
SIs the wiring neat, correct, and in accordance with the
wiring diagram?
SIs the unit properly grounded and protected (fused)?
SIs the thermostat correctly wired and in a good
location?
SAre all access panels in place and secure?
CHECK BLOWER OPERATION
SSet thermostat to FAN ON.
SThe indoor blower should come on.
CHECK COOLING OPERATION
SSet thermostat to force a call for cooling
(approximately 5ºF lower than the indoor ambient
temperature).
SThe outdoor unit should come on immediately and the
indoor blower should start between 30 − 60 seconds
later.
SCheck the airflow from a register to confirm that the
system is moving cooled air.
SSet the thermostat 5ºF higher than the indoor
temperature. The indoor blower and outdoor unit
should cycle off.
CHECK ELECTRIC HEATER (IF USED)
SSet 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.
SSet the thermostat so that it does not call for heat.
Allow up to 5 minutes for all sequencers to cycle off.
Operation
COOLING (COOLING ONLY OR HEAT PUMP)
When the thermostat calls for cooling, 24 volts is put on the
blower time−delay relay coil. After a delay, 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.
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.)
At the completion of the cooling demand and after the
relay’s time-delay, the compressor and outdoor fan will
cycle off.
HEATING (ELECTRIC HEAT ONLY)
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.
HEATING (HEAT PUMP)
When the thermostat calls for heating, 24 volts is put on the
blower time−delay relay coil. After a delay, 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. Circuit R and G
energizes the blower relay, starting the indoor blower
motor.
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
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.
TIME DELAY RELAY
On early production units, the indoor blower relay
energizes after a 30 second delay and it remains
energized for 30 seconds after the call is satisfied.
The indoor blower will remain on for approximately
30 seconds before cycling off.

Page 16
505059M 0511
In January 2006, the blower relay was changed to 1
second delay ON and 45 second delay OFF.
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.
Accessories
Contact your Lennox dealer for the following accessories:
SElectric Heat KitSee the accessory kit label on the
front panel of the air handler for the electric heat kit
options and accessories.
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.
SInspect 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.
SReplace disposable filters. Cleanable filters can be
cleaned by soaking in mild detergent and rinsing with
cold water.
SInstall 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.
SIf 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
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.
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.
REPAIRING DAMAGED INSULATION
Areas of condensation on the cabinet surface are an
indication that the insulation is in need of repair.
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.
1. CUT INSULATION IN X PATTERN
2. APPLY GLUE
3. PRESS GLUED TABS AGAINST CABINET
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.
Figure 15. Repairing Insulation