Lennox Signature CB31MV User manual

04/08 505,341M
*2P0408* *P505341M*
Page 1
E2008 Lennox Industries Inc.
Dallas, Texas, USA
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, 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 indoor coil as
specified in Lennox Engineering Handbook. Coils
previously charged with HCFC−22 must be
flushed.
INSTALLATION
INSTRUCTIONS
Dave Lennox Signature®
Collection CB31MV Units
MULTI−POSITION AIR HANDLER
505,341M
04/08
Supersedes 07/07
Table of Contents
CB31MV Up−flow/Down−flow Unit Dimensions 2. . . .
CB31MV Horizontal LH/RH Unit Dimensions 3. . . . . .
General Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . .
Requirements 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the Unit 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brazing Connections 8. . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the Condensate Drain 9. . . . . . . . . . . . . . . . .
Inspecting and Replacing Filters 9. . . . . . . . . . . . . . . . .
Sealing the Unit 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting the BDC3 Blower Control Board 9. . . . . . . .
Adjusting the Blower Speed 9. . . . . . . . . . . . . . . . . . . .
Making Electrical Connections 11. . . . . . . . . . . . . . . . . .
Repairing or Replacing Cabinet Insulation 20. . . . . . . . .
RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE
AB
D
C
E
MOTOR SHIPPING BOLT
TOP CAP SHIPPING BRACKET (REPLACE
SCREWS IN TOP CAP AFTER REMOVAL)
HORIZONTAL DRAIN PAN (SEE UP−FLOW
APPLICATIONS ON PAGE 4 AND
DOWN−FLOW APPLICATIONS ON PAGE 6 )
MOTOR SHIPPING BRACKET
HOUSING SUPPORT PAD
IMPORTANT INFORMATION TO INSTALLER
CHECK FOR AND REMOVE THE FOLLOWING ITEMS BEFORE OPERATING UNIT.
F
REFRIGERANT LINE CAPS [SEE
BRAZING CONNECTION ON PAGE 8]
G
CONFIGURATION JUMPERS (IF NECESSARY) (SEE
ADJUSTING THE BDC3 BLOWER CONTROL BOARD
ON PAGE 11.
Litho U.S.A.

Page 2
505341M 04/08
CB31MV Up−flow and Down−flow Unit Dimensions − Inches (mm)
DIMENSION A B C D E F G H
CB31MV−041 inches (mm) 51 (1295) 21-1/4 (540) 22-5/8 (502) 19-3/4 (575) 21 (533) 20 (508) 26-3/8 (670) 24-5/8 (625)
CB31MV−051, −065 inches (mm) 58-1/2 (1486) 21-1/4 (540) 24-5/8 (625) 19-3/4 (502) 23 (584) 20 (508) 27-7/8 (708) 30-5/8 (778)
OPTIONAL
ELECTRIC
HEAT
(FIELD
INSTALLED)
AIR FLOW
LIQUID
LINE
SUCTION
LINE
SUPPLY AIR
OPENING
RETURN AIR
FILTER
LOW VOLTAGE
INLETS
(TOP AND
RIGHT SIDE)
LINE VOLTAGE
INLETS
(TOP AND LEFT
SIDE)
RETURN AIR
TOP VIEW
A
BC
11-1/16 (281)
D
FE
COIL
PIPING
PLATE (SEE
DETAIL
BELOW)
3/4
(19)
3/4
(19)
3/4
(19)
5/8 (16)
5/8
(16)
1
(25)
5/8
(16)
5/8
(16)
FILTER ACCESS
H
G
AIR FLOW
LIQUID
LINE
SUCTION
LINE
RETURN
AIR
OPENING
SUPPLY
AIR
FILTER
SUPPLY
AIR
11-1/16
(281)
COIL
5/8
(16)
5/8
(16)
5/8
(16)
5/8
(16)
5/8
(16)
5/8
(16)
5/8
(16)
1
(25)
FILTER
ACCESS
TOP VIEW
FRONT VIEW
A
BC
D
F
E
H
G
OPTIONAL ELECTRIC
HEAT (FIELD INSTALLED)
LOW VOLTAGE
(RIGHT SIDE)
LINE VOLTAGE
(LEFT SIDE) SIDE VIEWFRONT VIEW SIDE VIEW
5/8
(16)
UP−FLOW POSITION DOWN−FLOW POSITION
PIPING
PLATE
(SEE
DETAIL
BELOW
LEFT)
BLOWER
BLOWER
DETAIL OF PIPING PLATE
LIQUID
LINE
SUCTION
LINE
1-3/4
(44)
2
(51)
1-1/8 (29)
4-3/8
(111)
2-3/4
(70)
5-3/8
(137)
3-1/2
(89)
CONDENSATE
DRAINS (2)

Page 3
CB31MV SERIES
CB31MV Horizontal Left− and Right−Hand Unit Dimensions − Inches (mm)
DIMENSION A B C D E F G H
CB31MV−041 inches (mm) 51 (1295) 21-1/4 (540) 22-5/8 (502) 19-3/4 (575) 21 (533) 20 (508) 26-3/8 (670) 24-5/8 (625)
CB31MV−051, −065 inches (mm) 58-1/2 (1486) 21-1/4 (540) 24-5/8 (625) 19-3/4 (502) 23 (584) 20 (508) 27-7/8 (708) 30-5/8 (778)
LIQUID
LINE
SUCTION LINE
SUPPLY
AIR
OPENING
FILTER
LOW VOLTAGE INLETS
(BOTTOM AND RIGHT SIDE)
TOP VIEW
FRONT VIEW
DETAIL OF PIPING PLATE
D
LIQUID
LINE
SUCTION
LINE
CONDENSATE
DRAINS (2) COIL
3/4
(19)
3/4
(19)
3/4
(19)
1-1/2
(38)
1-3/4
(44)
5-3/4
(146)
2
(51)
1-1/8 (29)
RETURN
AIR
OPENING
E
5/8 (16)
5/8 (16)
AIR
FLO
W
OPTIONAL ELECTRIC
HEAT
(FIELD INSTALLED)
11-1/16
(281)
LINE VOLTAGE INLETS
(TOP AND RIGHT SIDE)
5-3/8
(137)
4-3/8
(111)
LIQUID
LINE
SUCTION LINE
SUPPLY
AIR
OPENING
FILTER
LOW VOLTAGE INLETS
(TOP AND LEFT SIDE)
DETAIL OF PIPING PLATE
B
LIQUID
LINE
SUCTION
LINE
COIL
3/4
(19)
3/4
(19)
3/4
(19)
2
(51)
1-1/8 (29)
RETURN
AIR
OPENING
5/8 (16)
5/8 (16)
5/8 (16)
AIR
FLOW
OPTIONAL ELECTRIC HEAT
(FIELD INSTALLED)
LINE VOLTAGE INLETS
(BOTTOM AND LEFT SIDE)
5-3/8
(137)
4-3/8
(111)
HORIZONTAL POSITION (LEFT-HAND AIR DISCHARGE)
HORIZONTAL POSITION (RIGHT-HAND AIR DISCHARGE)
FILTER
ACCESS
FILTER
ACCESS
5-3/4
(146)
1-1/2
(38)
1-3/4
(44)
CONDENSATE
DRAINS (2)
5/8
(16)
5/8 (16)
1 (25)
1 (25)
11-1/16
(281)
BLOWER
BLOWER
END VIEWEND VIEW
END VIEWEND VIEW
TOP VIEW
FRONT VIEW
F
A
GH
A
GH
D
B
C
C
E
F
5/8 (16)

Page 4
505341M 04/08
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, 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
information, 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
General Information
The CB31MV air handler units are designed for installation
with optional field−installed electric heat and a matched
remote outdoor unit. These units are for indoor installation
only. The units are designed for multi−positional
installations and are shipped (completely assembled) from
the factory for installation in up−flow or horizontal
right−hand air discharge applications.
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. Check
equipment for shipping damage; if found, immediately
report damage to the last carrier.
Shipping and Packing List
Package 1 of 1 contains the following:
1Assembled air handler unit
2Drip shields (for down−flow application only)
Requirements
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 the following National Fire
Protection Association (NFPA) standards:
SNFPA No. 90A − Standard for Installation of Air
Conditioning and Ventilation Systems
SNFPA No. 90B − Standard for Installation of Residence
Type Warm Air Heating and Air Conditioning Systems
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.
Installing the Unit
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.
CB31MV units are factory−configured for installation in
up−flow or horizontal right−hand air discharge applications.
The units must be field−modified for installation in either
down−flow or horizontal left−hand air discharge
applications.
DISASSEMBLE AND REASSEMBLE AIR HANDLER
UNIT
The CB31MV air handler unit consists of two sections
which are shipped assembled from the factory. If
necessary, the unit may be disassembled to facilitate
setting the unit. Follow the steps below:
To disassemble:
Step 1. Remove access panels.
Step 2. Remove both blower and coil assemblies. This
will lighten the cabinet for lifting.
Step 3. Remove one screw from the left and right posts
inside the unit. Remove one screw from each
side on the back of the unit. Unit sections will
now separate.
To reassemble:
Step 1. Align cabinet sections together.
Step 2. Reinstall screws.
Step 3. Replace blower and coil assemblies.
Step 4. Replace access panel.
UP−FLOW AIR DISCHARGE APPLICATION
Use the following procedures to configure the unit for
up−flow operations:
Step 1. Remove access panels.
Step 2. Remove corrugated padding from the space
between the blower and coil assemblies.
Step 3. Discard drip shields which are shipped inside
corner post packaging. The shields are used in
down−flow applications only.
Step 4. The horizontal drain pan must be removed when
the coil blower is installed in the up−flow position.
Removing horizontal drain pain will allow proper
airflow and increase efficiency.

Page 5
CB31MV SERIES
Step 5. Place unit in desired location. Unit must be level.
Connect return and supply air plenums as
required using sheet metal screws.
Step 6. If the application will not include a return air
plenum, install the unit on a raised stand at least
14" from the floor to ensure proper air return.
Lennox offers an optional up−flow unit stand as
listed in table 1.
HORIZONTAL DRAIN PAN
(MUST BE REMOVED)
UP−FLOW/
DOWN−FLOW
DRAIN PAN
Figure 1. Up−flow Configuration
Table 1. Optional Unit Side Stand (Up−Flow Only)
Model Kit Number
−21, −26, and −31 45K31
−41 through −65. 45K32
HORIZONTAL RIGHT−HAND AIR DISCHARGE
APPLICATION
Use the following procedures to configure the unit for
horizontal right−hand discharge operations:
NOTE − For horizontal applications, a secondary drain pan
is recommended. Refer to local codes.
Step 1. Remove access panels and the horizontal drip
shield (−068 model) and the corrugated padding
between the blower and coil assembly. Discard
the corrugated padding and the down−flow drip
shields from the foam pads on top of the unit.
Step 2. Install the horizontal shield on the front edge of
the horizontal drain pan as illustrated in figure 2.
Step 3. No further adjustment is necessary. Set unit so
that it is sloped 1/4 inch towards the drain pan end
of the unit.
Step 4. If suspending the unit, it must be supported
along the entire length of the cabinet. If using
chain or strap, use a piece of angle iron or sheet
metal attached to the unit (either above or below)
so that the full length of the cabinet is supported.
Use securing screws no longer than 1/2 inch to
avoid damage to coil or filter as illustrated in
figure 3. Connect return and supply air plenums
as required using sheet metal screws.
NO ADJUSTMENT IS NECESSARY
HORIZONTAL DRIP SHIELD (−068
MODELS)
UP−LOAD / DOWN−FLOW
DRAIN PAN
HORIZONTAL DRAIN
PAN
DOWN−FLOW RAIL
Figure 2. Right−hand Discharge Configuration
HORIZONTAL RIGHT−HAND DISCHARGE
APPLICATION IN HIGH HUMIDITY AREAS
For horizontal applications in high humidity areas remove
the down−flow rail closest to the drain pan.
To remove rail:
Step 1. Remove the screws from the rail at the back of
unit and at the cabinet support rail.
Step 2. Remove the down−flow rail then replace screws.
Step 3. Seal around the exiting drain pipe, liquid line,
and suction line to prevent humid air from
infiltrating into the unit.
FRONT VIEW END VIEW
ANGLE IRON OR
SHEET METAL
ELECTRICAL INLET
CLEARANCE 4 IN. (102 MM)
1/2 IN. SCREWS MAXIMUM
Figure 3. Suspending Horizontal Unit
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.
HORIZONTAL LEFT−HAND AIR DISCHARGE
APPLICATION
HORIZONTAL
DRIP SHIELD
HORIZONTAL
DRAIN PAN
SECURING TAB ON
CABINET SUPPORT RAIL
DOWNFLOW
RAIL
Figure 4. Left−hand Air Discharge Configuration

Page 6
505341M 04/08
NOTE − For horizontal applications, a secondary drain pan
is recommended. Refer to local codes.
Use the following procedures to configure the unit for
horizontal left−hand discharge operations:
Step 1. Remove access panels. Remove corrugated
padding from space between the blower and coil
assemblies. Discard drip shields which are
shipped inside corner post packaging. The
shields are used in down−flow applications only.
Step 2. Slide coil assembly from unit. Remove the
horizontal drain pan.
Step 3. Remove drain plugs from back drain holes on
horizontal drain pan. Reinstall plugs on front
holes.
Step 4. Rotate drain pan 180° front to back and install it
on the opposite side of coil.
Step 5. Remove screws from top cap. Remove
horizontal drip shield screw located in the center
of the back coil end seal as illustrated in figure 5
on page 6.
Step 6. Rotate horizontal drip shield 180° front to back.
Step 7. Remove plastic plug from left hole on coil front
end seal and re-install plug in back hole.
Step 8. Reinstall horizontal drip shield screw in front coil
end seal. Drip shield should drain downward into
horizontal drain pan inside coil.
90º
BEND
CABINET
SUPPORT
COIL SHOWN IN UPLOAD POSITION FOR EASY CONVERSION
TOP CAP SCREWS
DRAIN PAN
REINSTALLED
HERE
DRIP
SHIELD
DRAIN PAN
SHIPPING
LOCATION
TOP CAP ROTATED TO
CORRECT POSITION
 DRAIN PLUGS 
REINSTALLED HERE REMOVED FROM HERE
BACK COIL
END SEAL
TOP
CAP
90º
BEND
ALIGN HOLES
WITH HOLES
IN COIL END
PLATE.
Figure 5. Field Modification (left−hand air discharge)
Step 9. Rotate top cap 180° front to back and align with
unused screw holes. Holes must align with front
and back coil end plates. Note that top cap has
a 45° bend on one side and 90° bend on the
other. The 90° bend must be on the same side
as the horizontal drain pan as illustrated in figure
figure 5.
NOTE − Use extreme care when reinstalling screws into
coil end plate engaging holes. Coil damage could result by
misalignment.
Step 10. From the up−flow position, flip cabinet 90° to the
left and set into place. Replace coil assembly.
Secure coil in place by bending down tab on
cabinet support rail as illustrated in figures 4 and
5.
NOTE − For horizontal applications in high humidity
areas, remove the down−flow rail closest to the drain pan.
To remove rail, remove screw from rail at back of unit and
at cabinet support rail. Remove down−flow rail then replace
screws. Also, seal around the exiting drain pipe, liquid and
suction lines to prevent infiltration of humid air.
Step 11. Knock out drain seal plate from access door.
Secure plate to cabinet front flange using the
provided screw.
Step 12. Flip access door and replace it on the unit.
Step 13. Set unit so that it is sloped 1/4 inch towards the
drain pan end of the unit as illustrated in figure
6. Connect return and supply air plenums as
required using sheet metal screws.
Step 14. If suspending the unit, it must be supported
along the entire length of the cabinet. If using
chain or strap, use a piece of angle iron or sheet
metal attached to the unit (either above or below)
so that the full length of the cabinet is supported.
Use securing screws no longer than 1/2 inch to
avoid damage to coil or filter as illustrated in
figure 3 on page 5. Connect return and supply
air plenums as required using sheet metal
screws.
THIS CORNER
SHOULD BE
1/4" HIGHER
THAN DRAIN
CORNER
DRAIN CORNER
THIS CORNER
SHOULD BE
1/4" HIGHER
THAN DRAIN
CORNER
LEFT−HAND AIR DISCHARGE
SHOWN; TYPICAL FOR
RIGHT−HAND DISCHARGE
Figure 6. Sloping for Proper Drainage
DOWN−FLOW AIR DISCHARGE APPLICATIONS
Use the following procedures to configure the unit for
down−flow operations:

Page 7
CB31MV SERIES
CAUTION
If electric heat section with circuit breakers
(ECB29/ECB31) is applied to down−flow CB31MV
unit, the circuit breakers must be rotated 180° to the
UP position. See ECB29/ECB31 installation instruc-
tions for more details.
The following table lists the sizes of the available drip
shields.
Table 1. Down−flow Drip Shields
Unit Part No. Length Width
CB31MV−41 LB−74272 17.875 4.6718
CB31MV−051, 065 LB−89864 19.875 4.6718
Step 1. Remove the access panels. If necessary,
remove the corrugated padding from the space
between the blower and coil assemblies.
Remove the drip shields from the inside of the
cornerpost packaging.
Step 2. Remove the coil assembly from the unit.
Step 3. Remove the horizontal drain pan to ensure peak
operating efficiency and proper air flow in the
down−flow position as illustrated in figure 7.
HORIZONTAL DRAIN
PAN (REMOVE FOR
DOWN−FLOW
APPLICATION)
UP−FLOW/DOWN−FLOW
DRAIN PAN
Figure 7. Down−flow Air Discharge Position
Step 4. Rotate cabinet 180° from the upright position. It
may be necessary to remove the blower
assembly to lighten the cabinet for lifting.
Step 5. Apply precut foam tape to the drip shields as
illustrated in figure 9. The foam tape creates a
seal between the drip shield and the coil to
prevent water from entering into the air stream.
Step 6. From the underside of the coil, install the
down−flow drip shield firmly in place as illustrated
in figure 10.
Step 7. Replace the coil assembly and blower (if it was
removed). Replace the coil access panel.
Step 8. Make sure the air handler unit is level. Connect
the return and supply air plenums as required
using sheet metal screws.
COMBUSTIBLE FLOOR
ADDITIVE BASE
PROPERLY SIZED
FLOOR OPENING
BLOWER
COIL UNIT FOR DOWN−FLOW
APPLICATIONS
Figure 8. Install Unit on Combustible Flooring
SIDE VIEW
APPLY TWO PIECES OF FOAM TAPE (PROVIDED) DOWN BOTH ENDS OF EACH
SHIELD. THE TAPE SHOULD MEASURE 4−3/4" X 2" (120 X 25 MM). ENSURE THAT
THE TAPE COVERS BOTH SIDES OF THE SHIELD EQUALLY.
APPLY THE LONGER PIECE OF FOAM TAPE BETWEEN THE PIECES ON EACH END.
THIS PIECE OF TAPE IS 1" WIDE.
Figure 9. Applying Foam Tape to Drip Shields
COIL
DRIP PAN
DRIP SHIELD WITHOUT
FOAM TAPE
COIL
DRIP PAN
DRIP SHIELD
WITH FOAM
TAPE
Figure 10. Down−flow Drip Shields
NOTE − For down−flow application, metal or class I supply
and return air plenums must be used.
For down−flow installation on combustible flooring, an
additive base must be used as illustrated in figure 8.

Page 8
505341M 04/08
Cut an opening appropriately sized for combustible base.
Base dimensions are illustrated in figure 11.
TOP VIEW
OPENING
1-5/8
(41)
SIDE VIEW
1-5/8
(41)
11-3/8
(289)
2 (51)
1-5/8
(41)
22-1/8 (562)
5/8
(16)
13-3/8 (340)
SUPPLY
AIR
OPENING
Inches
(mm)
23−1/4
(591)
20 (508)
FOR DOWN−FLOW
APPLICATIONS
Figure 11. Combustible Base Dimensions
After opening has been cut, set the additive base into
opening. Connect outlet air plenum to the additive base.
Set the unit on the additive base so flanges of the unit drop
into the base opening and seal against the insulation strips.
The unit is now locked in place. Install return air plenum
and secure with sheet metal screws.
Brazing Connections
WARNING
Danger of explosion!
Can cause equipment damage, injury,
or death.
When using a high pressure gas such
as dry nitrogen to pressurize a refrig-
eration or air conditioning system, use
a regulator that can control the pres-
sure down to 1 or 2 psig (6.9 to 13.8
kPa).
IMPORTANT
To prevent the build up of high levels of nitrogen
when purging, be sure it is done in a well ventilated
area. Purge low pressure nitrogen (1 to 2 psig)
through the refrigerant piping during brazing. This
will help to prevent oxidation and the introduction
of moisture into a system.
All CB31MV air handlers are equipped with a
factory−installed, internally mounted check/expansion
valve, which is suitable for use in R410−A applications. Use
Lennox L15 (sweat) series line sets as listed in table 2 on
page 9, or use field−fabricated refrigerant lines. L10 (flare)
line sets may be used by cutting off flare nut. Refer to the
piping section of the Lennox Unit Information Service
Manual for proper size, type and application of
field−fabricated lines.
AIR HANDLER UNIT
SUCTION LINE
LIQUID LINE
Figure 12. Brazing Connections
NOTE: CB31MV series evaporators use nitrogen or dry
air as a holding charge. If there is no pressure when the
rubber plugs are removed, check the coil or line set for
leaks before installing. After installation, pull a vacuum
on the line set and coil before releasing the unit charge
into the system.
NOTE: See outdoor unit instructions on how to flow
nitrogen through line sets.
Step 1. Remove access panel.
Step 2. Remove the refrigerant line caps from the
refrigerant lines.
Step 3. Use a wet rag to protect TXV sensing bulb (or
remove it) when brazing suction line
connections.
Step 4. Place a wet rag against piping plate and around
the suction line connection. The wet rag must be
in place to guard against damage to the paint.
Step 5. With the wet rag in place, position field provided
elbow fitting to air handler’s suction line and line
set. Start nitrogen flow before brazing.
Step 6. After the procedure is completed then remove
the wet rag.
Step 7. Place wet rag against piping plate and around
the liquid line connection. Position liquid line
elbow to air handler’s suction line and to line set.
Start nitrogen flow and begin brazing both
connections and after procedure is completed
then remove both wet rags.
Step 8. Refer to instructions provided with outdoor unit
for leak testing, evacuating and charging
procedures.
Step 9. Install access panel.

Page 9
CB31MV SERIES
Table 2. Refrigerant Line Kits
CB31MV
Units
Liquid
Line
Vapor/
Suction
Line
L10
Line Sets
L15
Line Sets
−41 3/8 in
(10 mm)
3/4 in.
(19 mm)
L10−41
20 ft. − 50 ft.
(6 m − 15 m)
L15−41
20 ft. − 50 ft.
(6 m − 15 m)
−51 3/8 in
(10 mm)
7/8 in.
(22 mm)
L10−65
30 ft. − 50 ft.
(9 m − 15 m)
L15−65
30 ft. − 50 ft.
(9 m − 15 m)
−65 3/8 in
(10 mm)
1−1/8 in.
(29 mm)
Field
Fabricated
Field
Fabricated
Installing the Condensate Drain
Connect main condensate drain and route downward to an
open drain or sump. Do not connect drain to a closed waste
system. Refer to figure 13 for typical condensate trap
configuration.
TO APPROVED DRAIN
TRAP MUST BE DEEP ENOUGH TO OFFSET
MAXIMUM STATIC DIFFERENCE (GENERALLY,
2 INCHES [51MM]).
DRAIN LINE SHOULD SLOPE A MINIMUM 1 INCH PER
10 FEET (25 MM PER 3 M)
TRAP (49P66)
VENT MUST EXTEND ABOVE THE HEIGHT OF THE COIL
DRAIN PAN BY 2 INCHES (51 MM). VENT
DRAIN PAN
Figure 13. Condensate Drain Connection
It is recommended that the auxiliary drain be connected to
a drain line for all units. If auxiliary drain is not connected, it
must be plugged with provided cap. For down−flow units,
the auxiliary drain MUST be connected and routed to a
drain. See figure 14 on page 9 for main and auxiliary
drain locations.
LEFT−HAND
DISCHARGE
MAIN DRAIN ON RIGHT
AUXILIARY DRAIN ON LEFT
UP−FLOW OR
DOWN−FLOW
RIGHT−HAND
DISCHARGE
Figure 14. Main and Auxiliary Drain Locations
The following practices are recommended to ensure
condensate removal:
SDrain piping should not be smaller than the drain
connections at drain pan.
SInstall a trap in the main drain line. The trap must be
deep enough to offset the difference in static pressure
between drain pan and atmosphere. Generally, two
inches is satisfactory for medium static applications.
SSlope horizontal runs 1 inch per 10 feet of drain line to
offset friction.
SLeave an open vent in the drain line, as shown in figure
13 to overcome line length, friction and static pressure.
SConstruct drains in a manner which will facilitate future
cleaning. Drains must not interfere with filter access as
illustrated in figure 13 on page 9 .
SRoute auxiliary drain to an area where homeowner will
notice it draining. The auxillary drain line does not
required venting or a trap. Refer to local codes.
Inspecting and Replacing Filters
IMPORTANT
Filter access panel must be in place during unit
operation. Excessive warm air entering the unit may
result in water blow−off problems.
Filters may be duct−mounted or installed in cabinet. A filter
is factory−installed. Note that filter access door fits over
access panel. Air leakage will occur if access panel is
placed over filter door.
Filters should be inspected monthly and must be cleaned
or replaced when dirty to assure proper furnace operation.
Units are equipped with standard throw−away type filters
which should be replaced when dirty.
To replace filter:
Step 1. Loosen the thumbscrews holding the filter panel
in place.
Step 2. Slide the filter out of the guides on either side of
cabinet.
Step 3. Insert new filter.
Step 4. Replace panel.
See table 3 for replacement filter sizes.
Table 3. Filter Dimensions
Unit Model No. Filter Size inches (mm)
CB31MV−41 20 x 22 (508 x 559)
CB31MV−51, −65 20 x 24 (508 x 610)
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.
Make sure the liquid line and suction line entry points are
sealed with either the provided flexible elastomeric thermal
insulation, or field provided material (e.g. Armaflex,
Permagum or equivalent). Any of the previously mention
materials may be used to seal around the main and
auxiliary drains, and around open areas of electrical inlets.
Adjusting the BDC3 Blower Control Board
CB31MV units are equipped with a variable speed motor
that is capable of maintaining a specified CFM throughout
the external static range. A particular CFM can be obtained
by positioning jumpers (COOL, HEAT, and ADJUST) on

Page 10
505341M 04/08
the BDC3 control board. The jumpers are labeled 1, 2, 3,
and 4. Each of the numbers corresponds with an air
volume (CFM) setting. The ADJUST jumper is labeled
Test, −, +, and Norm. The + and − pin settings are used to
add or subtract a percentage of the CFM selected. The
Test jumper is used to operate the motor in the test mode.
The delay jumper controls the timing for the fan delay.
Table 4. Blower Speed Tap Selection
CB31MV
Air Handler
RECOMMENDED SPEED TAP SELECTION
COOL HEAT
Condensing Unit Heat Pump
Condensing Unit With
Electric Heat Only Heat Pump With Electric Heat
−041 COOL PIN #3 COOL PIN #3 HEAT PIN #4 HEAT PIN #4
−051 COOL PIN #2 COOL PIN #2 HEAT PIN #1 HEAT PIN #1
−065 COOL PIN #3 COOL PIN #3 HEAT PIN #1 HEAT PIN #1
* Minimum setting for heat.
Figure 15 on page 10 provides an illustration of the BDC3
control board. Use tables 5 and 6 on page 12 to determine
the correct air volume for heat and cool speed taps.
JP1 15 PIN PLUG
(BOARD TO MOTOR)
ACCESSORY RELAY CONTACTS (DRIVES
OPTIONAL ACCESSORY RELAY)
OPERATIONAL SELECTOR PINS (AFFECTS
BOTH HEATING AND COOLING MODES)
DIAGNOSTIC
LEDS
HEATING SPEED
SELECTOR PINS
COOLING SPEED
SELECTOR PINS
FAN DELAY
SELECTOR PINS
Figure 15. BDC3 Variable Speed Control Board
Selections
Diagnostic LEDs located on the BDC3 control board are
provided to aid in identifying the unit’s mode of operation.
Certain scenarios will arise depending on the jumper
positions. Read through the jumper settings sections
before adjusting Blower speed. Refer to figure 15 for
identification.
Adjusting Blower Speed
DIAGNOSTIC LEDS
Step 1. RUN LED indicates there is a demand for the
Blower motor to run.
Step 2. CFM LED indicates the CFM at which the unit is
operating. The light flashes once for
approximately every 100 CFM. For example, if
the unit is operating at 1000 CFM, CFM LED will
flash 10 times. If the CFM is 1150, CFM LED will
flash 11 full times plus one fast or half flash.
At times the light may appear to flicker or glow. This takes
place when the control is communicating with the motor
between cycles. This is normal operation.
The appropriate speed according to application and CFM
need is selected by moving jumper pins.
IMPORTANT
Before changing jumper setting, make sure the
motor has completely stopped. Any jumper setting
change will not take place while the motor is
running.
Table 4 lists the recommended factory Blower speed tap
selections for CB31MV series units. These settings are for
nominal tonnage match−ups with the CB31MV. When
matched with other sizes, it is recommended that the CFM
be adjusted to approximately 400 CFM per ton.
To change jumper positions, gently pull the jumper off the
pins and place it on the desired set of pins. The following
section outlines the different jumper selections available
and conditions associated with each one as illustrated in
figure 15.
After the CFM for each application has been determined,
the jumper settings must be adjusted to reflect those given
in tables 5 and 6. From the tables, determine which row of
CFM volumes most closely matches the desired CFM.
Once a specific row has been chosen (+, NORMAL, or −),
CFM volumes from other rows cannot be used. Below are
descriptions of the jumper selections.
ADJUST JUMPERS
The ADJUST pins allow the motor to run at normal speed,
approximately 10% higher, or approximately 10% lower than
normal speed. Table 5 gives three rows (+, NORMAL, and −)
with their respective CFM volumes. Notice that the normal
adjustment setting for heat speed position #3 is 1315 CFM.
The + adjustment setting for that position is 1445 CFM and
for the − adjustment setting is 1185 CFM. After the
adjustment setting has been determined, chose the
remainder speed jumper settings from those offered in the
table in that row.
The TEST pin is available to bypass the BDC3 control and
run the motor at approximately 70% to test that the motor is
operational. This is beneficial primarily in troubleshooting.
G must be energized for motor to run.

Page 11
CB31MV SERIES
COOL JUMPERS
The COOL jumper is used to determine the CFM during
either 1) cooling or 2) heat pump operation without a call for
electric heat. These jumper selections are activated for
cooling when Y2 and DS terminals in the CB31MV are
energized and for heating when Y2 is energized.
Applications without the SignatureStatthumidity control
will provide either 70% of the COOL CFM during first−stage
cooling for two−speed outdoor units. 100% of COOL CFM
is provided for systems with a single−speed outdoor unit.
Applications with the SignatureStatthumidity control
create different CFM volumes. For example, during a
first−stage cooling call (two−speed outdoor unit) with
demand from the SignatureStattthermostat, the air
volume is 40% of the COOL jumper selection. For a normal
COOL (Pin #2 setting for CB31MV−41), the CFM is 1125;
the reduced speed is 450 CFM (1125 x 40% = 450). This
arrangement provides for additional dehumidification
during standard first stage cooling. See tables 7 and 8 for
various scenarios concerning use of the SignatureStatt
humidity control and the CB31MV series unit.
For applications with Harmony IIRzone control, the Blower
CFM volume is determined by the Harmony II control
center. The minimum air handler speed is predetermined
at 650 CFM for −41 series units and 850 CFM for −51 and
−65 series units. This speed is not adjustable. See
footnotes in tables 5 and 6.
With the thermostat set for Continuous Fan" and without a
call for heating or cooling, the CB31MV will provided 50%
of the COOL CFM selected.
NOTE − For two−speed heat pumps, air handler will operate
at 70% of the COOL selection until supplemental electric
heat is demanded. At that time, the air handler will operate
at the HEAT speed selected. This arrangement provides
for warmer supply air during second−stage heating.
HEAT" JUMPERS
The HEAT jumper is used to determine CFM during
electric heat operation only. These jumper selections are
activated only when W1 is energized.
DELAY JUMPERS
The DELAY jumper is used to set the specific motor fan
operation during cooling mode. Depending on the
application, one of four options may be chosen by moving
the jumper to the appropriate set of pins.
#1 Pins Jumpered 
AMotor runs at 100% until demand is satisfied.
OFFOFF
A B
BOnce demand is met, motor ramps down to stop.
#2 Pins Jumpered 
AMotor runs at 100% until demand is satisfied.
OFF
OFF
ABC
BOnce demand is met, motor runs at 100% for 45
seconds. Then,
Cramps down to stop.
NOTE − Blower OFF DELAY also applies during heat
pump operation
#3 Pins Jumpered 
AMotor runs at 82% for approximately 7−1/2
minutes. If demand has not been satisfied after
7−1/2 minutes,
Bmotor runs at 100% until demand is satisfied.
OFFOFF
AB C
COnce demand is met, motor ramps down to stop.
#4 Pins Jumpered 
AMotor runs at 50% for 30 seconds.
BMotor then runs at 82% for approximately 7−1/2
minutes. If demand has not been satisfied after
7−1/2 minutes.
CMotor runs at 100% until demand is satisfied.
DOnce demand is met, motor runs at 50% for 30
seconds. Then,
AB
OFFOFF
C D
E
Eramps down to stop.
Making Electrical Connections
Wiring must conform to the current National Electric Code
ANSI/NFPA No. 70, or Canadian Electric Code Part I, CSA
Standard C22.1, and local building codes. Refer to
following wiring diagrams. See unit nameplate for
minimum circuit ampacity and maximum overcurrent
protection size.
Select the proper supply circuit conductors in
accordance with tables 310−16 and 310−17 in the
National Electric Code, ANSI/NFPA No. 70 or tables 1
through 4 in the Canadian Electric Code, Part I, CSA
Standard C22.1.
WARNING
USE COPPER CONDUCTORS ONLY!
This unit is provided with knockouts for conduit. Refer to
figure 16 for unit schematic wiring diagram. Refer to
figures 17, 19, 20 and 21 for typical field wiring.
Separate openings have been provided for 24V low
voltage and line voltage. Refer to the dimension illustration
of specific location.
WARNING
Run 24V Class II wiring only through specified low
voltage opening. Run line voltage wiring only
through specified high voltage opening. Do not
combine voltage in one opening.

Page 12
505341M 04/08
Table 5. CB31MV-041 Air Handler Performance
0 through 0.80 in. w.g. (0 Through 200 Pa) External Static Pressure Range
ADJUST
Jumper
Setting
BDC3 Jumper Speed Position
HEAT Speed COOL Speed*
12341234
cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s
[phone] 1445 680 1545 730 1090 515 1225 580 1380 650 1545 730
NORM 1120 530 1215 575 1315 620 1400 660 975 460 1125 530 1275 600 1400 660
1010 475 1200 565 1185 560 1265 595 900 425 1000 470 1135 535 1265 595
* First−stage (two−stage units only) cooling is approximately 70% of the COOL speed rating.
Continuous fan speed is approximately 50% of COOL speed rating.
Lennox Harmony IIRZone Control Applications − Minimum air handler speed is approximately 380 cfm (180 L/s).
NOTE − The effect of static pressure, filter and electric heater resistance is included in the air volumes listed.
Table 6. CB31MV-051, −065 Air Handler Performance
0 through 0.80 in. w.g. (0 Through 200 Pa) External Static Pressure Range
ADJUST
Jumper
Setting
BDC3 Jumper Speed Position
HEAT Speed COOL Speed*
12341234
cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s
[phone] 2090 985 2150 1015 1625 765 1820 860 2055 970 2145 1010
NORM 1705 805 1800 850 1900 895 2005 945 1425 670 1625 765 1805 850 2005 945
1560 735 1625 765 1720 810 1770 835 1205 570 1375 650 1555 735 1725 815
* First−stage (two−stage units only) cooling is approximately 70% of the COOL speed rating.
Continuous fan speed is approximately 50% of COOL speed rating.
Lennox Harmony IIRZone Control Applications − Minimum air handler speed is approximately 400 cfm (190 L/s).
NOTE − The effect of static pressure, filter and electric heater resistance is included in the air volumes listed.
Table 7. CB31MV SignatureStattand Single Stage Outdoor Unit
Operating
Sequence System Demand System Response
System
Condition Step
Thermostat Demand Relative Humidity
Compressor
Air
Handler
CFM
(COOL) Comments
Y1 O G W1 Status D
NO CALL FOR DEHUMIDIFICATION
Normal
Operation 1 On On On Acceptable 24 VAC High 100%
Compressor and indoor air
handler follow thermostat de-
mand
BASIC MODE (only active on a Y1 thermostat demand)
Normal
Operation 1 On On On Acceptable 24 VAC High 100% SignatureStattenergizes Y1
and de−energizes D on a call
for dehumidification
Dehumidification
Call 2 On On On Demand 0 VAC High 60%/65%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal
Operation 1 On On On Acceptable 24 VAC High 100% Dehumidification mode begins
when humidity is greater than
set point
Dehumidification
call 2 On On On Demand 0 VAC High 60%/65%*
Dehumidification
call ONLY 1 On On On Demand 0 VAC High 60%/65%* SignatureStattwill try to
maintain room humidity set-
point by allowing the room
space to maintain a cooler
room thermostat setpoint**
Jumpers at indoor unit with a single stage outdoor unit
With Condensing unit − Y1 to Y2 and R to O
With Heat Pump − Y1 to Y2
Lennox SignatureStattused for these applications are 51M26 − 1 heat / 1 cool or 51M28 − 2 heat / 2 cool heat pump
* During dehumidification, cooling air handler speed is as follows: 65% of COOL cfm for −41units, 60% COOL cfm for −51 and −61 units
** In Precision mode, SignatureStattthermostat built BEFORE October 2003 will maintain room temperature up to 3°F (1.8°C) cooler than room
thermostat setting. Precision thermostat built AFTER October 2003 will maintain room temperature up to 2°F (1.2°C) cooler than the room thermo-
stat setting.

Page 13
CB31MV SERIES
Table 8. CB31MV, SignatureStattand Two−Stage Outdoor Unit
Operating
Sequence System Demand System Response
System
Condition Step
Thermostat Demand Relative Humidity
Compressor
Air Handler
CFM
(COOL) Comments
Y1 Y2 O G W1 W2 Status D
NO CALL FOR DEHUMIDIFICATION
Normal
Operation − Y1 1 On On On Acceptable 24 VAC Low 70% Compressor and in-
door air handler fol-
low thermostat de-
mand
Normal
Operation − Y2 2 On On On On Acceptable 24 VAC High 100%
ROOM THERMOSTAT CALLS FOR FIRST STAGE COOLING
BASIC MODE (only active on a Y1 thermostat demand)
Normal
Operation 1 On On On Acceptable 24 VAC Low 70% SignatureStat ener-
gizes Y2 and de−en-
ergizes D on a call
for dehumidification
Dehumidificatio
n Call 2 On On On On Demand 24 VAC High 60%/65%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal
Operation 1 On On On Acceptable 24 VAC Low 70% Dehumidification
mode begins when
humidity is greater
than set point
Dehumidificatio
n call 2 On On On On Demand 0 VAC High 60%/65%*
Dehumidificatio
n call ONLY 1 On On On On Demand 0 VAC High 60%/65%*
**SignatureStatt
will try to maintain
room humidity set-
point by allowing the
room space to
maintain a cooler
room thermostat
setpoint
ROOM THERMOSTAT CALLS FOR FIRST AND SECOND STAGE COOLING
BASIC MODE (only active on a Y1 thermostat demand)
Normal
Operation 1 On On On On Acceptable 24 VAC High 100% SignatureStat ener-
gizes Y2 and de−en-
ergizes D on a call
for dehumidification
Dehumidificatio
n Call 2 On On On On Demand 0 VAC High 60%/65%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal
Operation 1 On On On On Acceptable 24 VAC High 100% Dehumidification
mode begins when
humidity is greater
than set point
Dehumidificatio
n call 2 On On On On Demand 0 VAC High 60%/65%*
Dehumidificatio
n call ONLY 1 On On On On Demand 0 VAC High 60%/65%*
**SignatureStatt
will try to maintain
room humidity set-
point by allowing the
room space to
maintain a cooler
room thermostat
setpoint
Jumpers at indoor unit with a two stage outdoor unit
With Condensing unit − R to O
With Heat Pump − none
Lennox SignatureStattused for these applications are 51M27 − 2 heat / 2 cool or 51M28 − 2 heat / 2 cool heat pump.
* During dehumidification, cooling air handler speed is as follows: 65% of COOL cfm for −41units, 60% COOL cfm for −51 and −61 units
** In Precision mode, SignatureStattthermostat built BEFORE October 2003 will maintain the room temperature up to 3°F (1.8°C) cooler than room
thermostat setting. Precision thermostat built AFTER October 2003 will maintain the room temperature up to 2°F (1.2°C) cooler than the room ther-
mostat setting.

Page 14
505341M 04/08
Figure 16. CB31MV Blower Coil Unit Typical Wiring Diagram

Page 15
CB31MV SERIES
LINE VOLTAGE − FIELD-INSTALLED
CLASS 2 VOLTAGE − FIELD-INSTALLED NEC/CEC
NOTE − ALL REMAINING WIRES FACTORY-INSTALLED
TO EXTERNAL LOAD 24VAC AT .5 AMP MAXIMUM
NEC/CEC CLASS 2, 3 VA
FACTORY INSTALLED JUMPERS. − R" to O" USED ONLY IN CONDENSING UNIT APPLICATIONS. REMOVE IN HEAT
PUMP APPLICATIONS. REMOVE DS" TO Y1" JUMPER WHEN HUMIDITY CONTROL THERMOSTAT (SIGNATURES-
TATTIS USED. REMOVE Y1" TO Y2" JUMPER IN TWO−STAGE COOLING APPLICATIONS.
FACTORY INSTALLED JUMPER
NOTE − USE COPPER CONDUCTORS ONLY
Figure 17. Cooling Application

Page 16
505341M 04/08
LINE VOLTAGE − FIELD-INSTALLED
CLASS 2 VOLTAGE − FIELD-INSTALLED NEC/CEC
NOTE − ALL REMAINING WIRES FACTORY-INSTALLED
TO EXTERNAL LOAD 24VAC AT .5 AMP MAXIMUM
NEC/CEC CLASS 2, 3 VA
FACTORY INSTALLED JUMPERS. − R" to O" USED ONLY IN CONDENSING UNIT APPLICATIONS. REMOVE IN HEAT
PUMP APPLICATIONS. REMOVE DS" TO Y1" JUMPER WHEN HUMIDITY CONTROL THERMOSTAT (SIGNATURES-
TATTIS USED. REMOVE Y1" TO Y2" JUMPER IN TWO−STAGE COOLING APPLICATIONS.
FACTORY INSTALLED JUMPER
NOTE − USE COPPER CONDUCTORS ONLY
WHEN TWO-STAGE THERMOSTAT IS USED, CONNECT SECOND-STAGE HEAT BULB TO TERMINAL W2," REMOVE
JUMPER BETWEEN TERMINALS R" AND W2"
THERMOSTAT HEAT ANTICIPATION SETTING .4 AMP (ELECTRIC HEAT)
Figure 18. Cooling Application with Electric Heat

Page 17
CB31MV SERIES
3
FACTORY INSTALLED JUMPER
5
5
FUSE
1
4
7
3
6
9
CIRCUIT 1
FIELD−SUPPLIED
WIRE NUTS
6
6
7
7
K20 INDOOR
BLOWER RELAY
(Black)
(Orange)
FACTORY INSTALLED JUMPERS. − R" to O" used only in con-
densing unit applications. Remove in heat pump applications.
Remove DS" to Y1" jumper when humidity control (SignatureStatt) is
used.
Remove Y1" to Y2" jumper in two−stage cooling applications.
3
4
4
33
Figure 19. Cooling Application with Electric Heat

Page 18
505341M 04/08
2
2
3
3
RED (POWER)
2
FACTORY INSTALLED JUMPERS − R" to O" used only in condensing
unit applications. Remove in heat pump applications.
Remove DS" to Y1" jumper when CCB1 humidity control (A20) is used.
Remove Y1" to Y2" jumper in two−stage cooling applications.
FACTORY INSTALLED JUMPER
Remove R" to O" factory−installed jumper
in heat pump applications.
Figure 20. Heat Pump

Page 19
CB31MV SERIES
6
FACTORY INSTALLED JUMPER
S23
K22
RED (POWER)
1
2
Remove R" to O" factory−
installed jumper in heat
pump applications.
FACTORY INSTALLED JUMPERS. − R" TO O" USED ONLY IN CONDENSING UNIT
APPLICATIONS. REMOVE IN HEAT PUMP APPLICATIONS.
REMOVE DS" TO Y1" JUMPER WHEN CCB1 HUMIDITY CONTROL (A20) IS USED.
REMOVE Y1" TO Y2" JUMPER IN TWO−STAGE COOLING APPLICATIONS.
66
3
4
5
6
2
Figure 21. Heat Pump with Electric Heat

Page 20
505341M 04/08
Repairing or Replacing Cabinet Insulation
IMPORTANT
DAMAGED INSULATION MUST BE REPAIRED OR
REPLACED before the unit is put back into
operation. Insulation 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 22. Repairing Insulation
WARNING
Electric Shock Hazard.
Can cause injury or death.
Foil-faced insulation has conductive characteris-
tics similar 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 break-
ers), the current can be enough to cause an electric
shock hazard that could cause personal injury or
death.