Lennox XPG20 User manual

06/09 506238−01
*2P0609* *P506238-01*
Page 1
E2009 Lennox Industries Inc.
Dallas, Texas, USA
RETAIN THESE INSTRUCTIONS
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.
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 XPG20
SunSourcetComfort
System
SOLAR ASSIST HEAT PUMPS
506238−01
06/09
Supersedes 05/09
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Field Supplied Components 2. . . . . . . . . . . . . . . . . . . . .
Unit Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . . . . .
Control Panel Parts Arrangement 3. . . . . . . . . . . . . . . .
Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . .
System Overview 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Gauge Set 4. . . . . . . . . . . . . . . . . . . . . . . . . .
Recovering Refrigerant from Existing System 6. . . . .
Removing Existing Outdoor Unit 6. . . . . . . . . . . . . . . . .
Positioning New Outdoor Unit 7. . . . . . . . . . . . . . . . . . .
Removing and Installing Panels 8. . . . . . . . . . . . . . . . .
New or Replacement Line Set 9. . . . . . . . . . . . . . . . . . .
Brazing Connections 11. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing the System 13. . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing the System 15. . . . . . . . . . . . . . . . . . . . . . .
Evacuating the System 17. . . . . . . . . . . . . . . . . . . . . . . . .
Servicing Unit Delivered Void of Charge 18. . . . . . . . . .
Electrical 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Solar Module Setup and Connections 20. . . . . . . . . . . .
Unit Start−Up 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing Charge 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding or Removing Refrigerant 26. . . . . . . . . . . . . . . .
System Operations 29. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lennox System Operation Monitor (LSOM) 29. . . . . . .
LSOM Module and System Troubleshooting LEDs 30.
Defrost System 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrost Control Board Diagnostic LEDs 39. . . . . . . . . . .
Maintenance 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Homeowner Information 40. . . . . . . . . . . . . . . . . . . . . . . .
Field Operational Checklist 42. . . . . . . . . . . . . . . . . . . . .
Start−Up and Performance Checklist 43. . . . . . . . . . . . .
Litho U.S.A.

Page 2
506238−01 06/09
Unit Dimensions −− Inches (mm)
39−1/2
(1003)
1 (25)
LIQUID
LINE
INLET
SIDE VIEW ACCESS VIEW
DISCHARGE AIR
4−5/8
(117)
BASE
16−7/8
(429)
8−3/4
(222)
26−7/8
(683)
3−3/4 (95)
30−3/4
(781)
3−1/8
(79)
SUCTION
LINE
INLET
UNIT SUPPORT
FEET
35−1/2
(902)
18−1/2
(470)
8 (203)
4−1/2
(114)
ELECTRICAL INLET
(HIGH VOLTAGE)
37 (940)
SOLAR
MODULE
WIRING
ELECTRICAL INLET
(CONTROL WIRING
− LOW VOLTAGE)
Field Supplied Components
The followings items are field supplied (not included).
Parts Lennox Catalog Numbers
Solar Module (see Figure 17 for specifications) 48W00
Solar Module Mounting Kit − Roof applications 48W01
Solar Module Mounting Kit − Pole applications 48W02
DC rated disconnect (15A)
48W03
DC ground fault (if required)
DC surge arrestor
MC4 Cable 12 Gauge., 10 foot single wire (module leads to junction box) 48W04

Page 3
XPG20 SERIES
Unit Parts Arrangement
CONTACTOR
DEFROST
CONTROL
VAPOR VALVE AND GAUGE PORT
TWO−STAGE COMPRESSOR
OUTDOOR FAN
SOLAR ASSIST DC MOTOR
LENNOX SYSTEM OPERATION
MONITOR (LSOM)
RUN CAPACITOR
DISCHARGE LINE
REVERSING VALVE
SOLAR PANEL
TERMINAL BLOCK
BI−FLOW FILTER DRIER
FAN MOTOR
SOLAR ASSIST DC MOTOR
COUPLER
HIGH PRESSURE SWITCH
LOW PRESSURE
SWITCH
COMPRESSOR TERMINAL
PLUG
FAN MOTOR MOUNT
Control Panel Parts Arrangement
GROUND LUG
HIGH VOLTAGE FIELD
CONNECTIONS
CONTACTOR−1POLE,25A
(K1−1)
DEFROST CONTROL BOARD
(A108)
LOW VOLTAGE − CONTROL WIRE TIE
LSOM MODULE (A132) TERMINAL BLOCK − TWO POSITION
(SOLAR)
CAPACITOR
(C12)
DEFROST RELAY SOLAR FAN
(K227)
SOLAR FAN RELAY (24VAC) (K228)

Page 4
506238−01 06/09
WARNING
This product and/or the indoor unit it is matched
with may contain fiberglass wool.
Disturbing the insulation during installation,
maintenance, or repair will expose you to fiberglass
wool dust. 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
Shipping and Packing List
Check unit for shipping damage. Consult last carrier
immediately if damage is found.
1  Assembled outdoor unit.
1  Bag assembly that consist of the following:
1  Bushing (for low voltage wiring)
2  Isolation grommets for liquid and suction lines
System Overview
The SunSourcetComfort System heat pump, which will
also be referred to in this instruction as the outdoor unit,
uses HFC−410A refrigerant. This outdoor unit must be
installed with a matching indoor unit and line set as outlined
in the Lennox XPG20 Engineering Handbook.
This outdoor unit is designed for use in systems that use
check thermal expansion valve (CTXV) refrigerant
metering device.
Operating Gauge Set
This instruction is intended as a general guide and do not
supersede local codes in any way. Consult authorities who
have jurisdiction before installation.
TORQUE REQUIREMENTS
When servicing or repairing HVAC components, ensure
the fasteners are appropriately tightened. Table 1 list
torque values for fasteners.
IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and
fitted snugly over the cap before tightening.
IMPORTANT
Only use Allen wrenches of sufficient hardness
(50Rc − Rockwell Harness Scale minimum). Fully
insert the wrench into the valve stem recess.
Service valve stems are factory−torqued (from 9
ft−lbs for small valves, to 25 ft−lbs for large valves) to
prevent refrigerant loss during shipping and
handling. Using an Allen wrench rated at less than
50Rc risks rounding or breaking off the wrench, or
stripping the valve stem recess.
See the Lennox Service and Application Notes
#C−08−1 for further details and information.
Table 1. Torque Requirements
Parts Recommended Torque
Service valve cap 8 ft.− lb. 11 NM
Sheet metal screws 16 in.− lb. 2 NM
Machine screws #10 28 in.− lb. 3 NM
Compressor bolts 90 in.− lb. 10 NM
Gauge port seal cap 8 ft.− lb. 11 NM
Coupler Set Screws 150 in.− lb. 17 NM
Torque Arm Nut 55 in.− lb 6 NM
Assist Motor Bolts 35 in.− lb. 4 NM
Motor Mount Wire
Bracket
55 in.− lb 6 NM

12
3
4
5
6
7
8
9
10
11 12
1/6 TURN
1/12 TURN
12
3
4
5
6
7
8
9
10
11 12
Page 5
XPG20 SERIES
USING MANIFOLD GAUGE SET
When checking the system charge, use only a manifold
gauge set that features low−loss and anti−blow back
fittings.
(VALVE STEM
SHOWN CLOSED)
INSERT HEX
WRENCH HERE
VALVE STEM
FRONT-SEATED
TO OUTDOOR
UNIT
SERVICE PORT
CORE
TO INDOOR
UNIT
SERVICE PORT
SERVICE PORT
CAP
CLOSED TO BOTH
INDOOR AND OUTDOOR
UNITS
STEM CAP
ANGLE−TYPE SERVICE VALVE
(FRONT−SEATED CLOSED)
SERVICE PORT
SERVICE PORT
CORE
TO OUTDOOR
UNIT
STEM CAP
(VALVE STEM
SHOWN OPEN)
INSERT HEX
WRENCH HERE
SERVICE PORT
CAP
TO INDOOR
UNIT
OPEN TO BOTH
INDOOR AND
OUTDOOR
UNITS
ANGLE−TYPE SERVICE VALVE
(BACK−SEATED OPENED)
BALL (SHOWN
CLOSED)
SERVICE PORT
CORE
TO INDOOR UNIT
TO OUTDOOR UNIT
TO OPEN ROTATE STEM
COUNTERCLOCKWISE 90°.
TO CLOSE ROTATE STEM
CLOCKWISE 90°.
SERVICE PORT
SERVICE PORT CAP
STEM CAP
VALVE
STEM
OPEN TO LINE SET WHEN
VALVE IS CLOSED, TO BOTH
LINE SET AND UNIT WHEN
VALVE IS OPEN.
BALL−TYPE SERVICE
VALVE
Figure 1. Various Types of Service Valves
Manifold gauge set used with HFC−410A refrigerant
systems must be capable of handling the higher system
operating pressures. The gauges should be rated for use
with pressures of 0 − 800 psig on the high side, and a low
side of 30" vacuum to 250 psig with dampened speed to
500 psi. Gauge hoses must be rated for use at up to 800
psig of pressure with a 4000 psig burst rating.
OPERATING SERVICE VALVES
The liquid and vapor line service valves are used for
removing refrigerant, flushing, leak testing, evacuating,
checking charge and charging.
Each valve is equipped with a service port which has a
factory−installed valve stem as illustrated in Figure 1.
To Access Service Port:
A service port cap protects the service port core from
contamination and serves as the primary leak seal.
1. Remove service port cap with an appropriately sized
wrench.
2. Connect gauge to the service port.
3. When testing is completed, replace service port cap and
tighten as follows:
DWith Torque Finger Wrench:
tighten and then tighten per
Table 1.
DWithout Torque Wrench:
Finger tighten and use an
appropriately sized wrench to
turn an additional 1/6 turn.
Operating Angle−Type Service Valve:
1. Remove stem cap with an appropriately sized wrench.
2. Use a service wrench with a hex−head extension
(3/16" for liquid-line valve sizes and 5/16" for
vapor-line valve sizes) to back the stem out
counterclockwise as far as it will go.
Operating Ball−Type Service Valve:
1. Remove stem cap with an appropriately sized wrench.
2. Use an appropriately sized wrenched to open.
STo open valve, roate stem counterclockwise 90°.
STo close rotate stem clockwise 90°.
Reinstall Stem Cap:
Replace the stem cap and tighten as follows:
SWith Torque Wrench: Finger
tighten and then tighten per Table 1.
SWithout Torque Wrench: Finger
tighten and use an appropriately
sized wrench to turn an
additional 1/12 turn clockwise.
NOTE Later in the procedure, the HFC−410A container
will be replace by the nitrogen container. A label with
specific torque requirements may be affixed to the stem
cap. If the label is present, use the specified torque.

Page 6
506238−01 06/09
Recovering Refrigerant from Existing
System
Connect gauge set as illustrated in Figure 2 for removing
refrigerant.
MANIFOLD GAUGES
RECOVERY
MACHINE
CLEAN
RECOVERY
CYLINDER
OUTDOOR
UNIT
HIGH
LOW
CONNECT TO THE EXISTING UNIT A GAUGE SET, CLEAN RECOVERY
CYLINDER AND A RECOVERY MACHINE. USE THE INSTRUCTIONS
PROVIDED WITH THE RECOVERY MACHINE ON HOW TO SETUP THE
CONNECTIONS.
Figure 2. Setup Gauge Set
REMOVING REFRIGERANT
Remove existing HCFC−22 refrigerant using one of the
following procedures:
METHOD 1:
If the existing outdoor unit is not equipped with shut−off
valves, or if the unit is not operational and you plan to use
the existing HCFC−22 to flush the system.
Remove all HCFC−22 refrigerant from the existing system.
Check gauges after shutdown to confirm that the entire
system is completely void of refrigerant.
METHOD 2:
Use this method if the existing outdoor unit is equipped
with manual shut−off valves, and plan on using new
HCFC−22 refrigerant to flush the system.
IMPORTANT
Some system configurations may contain higher
than normal refrigerant charge due to either large
internal coil volumes, and/or long line set. The
following conditions may cause the compressor to
stop functioning:
The following devices could prevent full system charge
recovery into the outdoor unit:
SOutdoor unit’s high or low−pressure switches (if
applicable) when tripped can cycled the compressor
OFF.
SCompressor can stop pumping due to tripped internal
pressure relief valve.
SCompressor has internal vacuum protection that is
designed to unload the scrolls (compressor stops
pumping) when the pressure ratio meets a certain
value or when the suction pressure is as high as 20
psig. (Compressor suction pressures should never be
allowed to go into a vacuum.
Once the compressor can not pump down to a lower
pressure due to one of the above system conditions, shut
off the suction valve. Turn OFF the main power to unit and
use a recovery machine to recover any refrigerant left in
the indoor coil and line set.
Perform the following task:
1. Start the existing HCFC−22 system in the cooling
mode and close the liquid line valve.
2. Pump as much of the existing HCFC−22 refrigerant
with the compressor back into the outdoor unit until
you have reached the limitations of the outdoor
system. Turn the outdoor unit main power OFF and
use a recovery machine to remove the remaining
refrigerant in the system.
NOTE  It may be necessary to bypass the low pressure
switches if equipped to ensure complete refrigerant
evacuation.
3. When the low side system pressures reach 0 psig,
close the suction line valve.
4. Check gauges after shutdown to confirm that the
valves are not allowing refrigerant to flow back into the
low side of the system.
Removing Existing Outdoor Unit
Perform the following task at the existing outdoor unit:
SDisconnect line set at the service valves.
SDisconnect electrical service at the disconnect switch
as illustrated in Figure 3.
SRemove old outdoor unit.
SERVICE
DISCONNECT
SWITCH
MAIN FUSE
BOX/BREAKER
PANEL
Disconnect all power to the existing outdoor unit at the disconnect
switch or main fuse box/breaker panel.
Figure 3. Disconnect Power

Page 7
XPG20 SERIES
Positioning New Outdoor Unit
CAUTION
In order to avoid injury, take proper precaution when
lifting heavy objects.
See Unit Dimensions on page 3 for sizing mounting slab,
platforms or supports. Refer to Figure 4 for mandatory
installation clearance requirements.
SEE NOTES BELOW THIS FIGURE FOR FURTHER DETAILS.
CONTROL PANEL
ACCESS LOCATION
Figure 4. Installation Clearances
NOTES:
SService clearance of 30 in. (762 mm) must be
maintained on one of the sides adjacent to the control
panel.
SClearance to one of the other three sides must be 36
in. (914 mm).
SClearance to one of the remaining two sides may be
12 in. (305 mm) and the final side may be 6 in. (152
mm).
S48 in. (1219 mm) clearance required on top of unit.
SA clearance of 24 in. (610 mm) must be maintained
between two units.
POSITIONING CONSIDERATIONS
Consider the following when positioning the unit:
SSome localities are adopting sound ordinances based
on the unit’s sound level registered from the adjacent
property, not from the installation property. Install the
unit as far as possible from the property line.
SWhen possible, do not install the unit directly outside
a window. Glass has a very high level of sound
transmission. For proper placement of unit in relation
to a window see the provided illustration in Figure 5.
SIn locating and positioning the unit, take into
consideration where the solar module will be located
and/or how the wire can or will be routed to it.
INSTALL UNIT AWAY FROM
WINDOWS
TWO 90° ELBOWS INSTALLED IN
LINE SET WILL REDUCE LINE SET
VIBRATION.
Figure 5. Outside Unit Placement
PLACING UNIT ON SLAB
When installing unit at grade level, the top of the slab
should be high enough above grade so that water from
higher ground will not collect around the unit. The slab
should have a slope tolerance as described in Figure 6.
NOTE  If necessary for stability, anchor unit to slab as
described in Stabilizing Unit on Uneven Surfaces on page 9.
INSTALL UNIT LEVEL OR, IF ON A SLOPE, MAINTAIN SLOPE
TOLERANCE OF 2 DEGREES (OR 2 INCHES PER 5 FEET [50 MM
PER 1.5 M]) AWAY FROM BUILDING STRUCTURE.
MOUNTING
SLAB
BUILDING
STRUCTURE
GROUND LEVEL
Figure 6. Slab Mounting at Ground Level

Page 8
506238−01 06/09
ELEVATING THE UNIT
These units are outfitted with elongated support feet as
illustrated in Figure 7.
LEG DETAIL
BASE
2" (50.8MM) SCH
40 FEMALE
THREADED
ADAPTER
Figure 7. Elevated Slab Mounting using Feet
Extenders
If additional elevation is necessary, raise the unit by
extending the height of the unit support feet. This may be
achieved by using a 2" SCH 40 female threaded adapter.
The specified coupling will fit snuggly into the recessed
portion of the feet. Use additional 2" SCH 40 male threaded
adaptors which can be threaded into the female threaded
adaptors to make additional adjustments to the level of the
unit.
NOTE  Keep the height of extenders short enough to
ensure a sturdy installation. If it is necessary to extend
further, consider a different type of field−fabricated
framework that is sturdy enough for greater heights.
Removing and Installing Panels
CAUTION
To prevent personal injury, or damage to panels,
unit or structure, be sure to observe the following:
While installing or servicing this unit, carefully stow
all removed panels out of the way, so that the panels
will not cause injury to personnel, nor cause
damage to objects or structures nearby, nor will the
panels be subjected to damage (e.g., being bent or
scratched).
While handling or stowing the panels, consider any
weather conditions, especially windy conditions,
that may cause panels to be blown around and
battered.
WARNING
Unit must be grounded in accordance
with national and local codes.
Electric Shock Hazard. Can cause
injury or death.
Line voltage is present at all
components when unit is not in
operation on units with single-pole
contactors. Disconnect all remote
electric power supplies before
opening access panel. Unit may have
multiple power supplies.
ACCESS PANEL
Removal and reinstallation of the access panel is
illustrated in Figure 8.
REMOVE 4 SCREWS TO REMOVE
PANEL FOR ACCESSING
COMPRESSOR AND CONTROL.
POSITION PANEL WITH HOLES
ALIGNED; INSTALL SCREWS AND
TIGHTEN.
Figure 8. Access Panel
LOUVERED PANELS
Remove the louvered panels as follows:
1. Remove two screws, allowing the panel to swing open
slightly.
2. Hold the panel firmly throughout this procedure.
Rotate bottom corner of panel away from hinged
corner post until lower three tabs clear the slots as
illustrated in Figure 9, Detail B.
3. Move panel down until lip of upper tab clears the top
slot in corner post as illustrated in Figure 9, Detail A.
Position and Install PanelPosition the panel almost
parallel with the unit as illustrated in Figure 9, Detail D with
the screw side as close to the unit as possible. Then, in a
continuous motion:
SSlightly rotate and guide the lip of top tab inward as
illustrated in Figure 9, Details A and C; then upward
into the top slot of the hinge corner post.
SRotate panel to vertical to fully engage all tabs.
SHolding the panel’s hinged side firmly in place, close
the right−hand side of the panel, aligning the screw
holes.

Page 9
XPG20 SERIES
Detail A
Detail C
Detail B
ROTATE IN THIS DIRECTION; THEN
DOWN TO REMOVE PANEL
SCREW
HOLES
LI
P
Panel shown slightly rotated to allow top tab to exit (or enter)
top slot for removing (or installing) panel.
Maintain minimum panel angle (as close to parallel with the unit
as possible) while installing panel.
PREFERRED
ANGLE FOR
INSTALLATION
Detail D
ANGLE MAY BE
TOO EXTREME
HOLD DOOR FIRMLY ALONG THE HINGED SIDE
TO MAINTAIN FULLY−ENGAGED TABS
IMPORTANT! Do not allow panels to hang on unit by top tab. Tab is
for alignment and not designed to support weight of panel.
Figure 9. Removing/Installing Louvered Panels
When panel is correctly positioned and aligned, insert the
screws and tighten.
STABILIZING UNIT ON UNEVEN SURFACES
With unit positioned at installation site, remove two side
louvered panels to expose the unit base pan. Install the
brackets as illustrated in Figure 10 using conventional
practices. Replace the panels after installation is
complete.
To help stabilize an outdoor unit, some installations may
require strapping the unit to the pad using brackets and
anchors commonly available in the marketplace.
IMPORTANT
Unit Stabilizer Bracket Use (field−provided):
Always use stabilizers when unit is raised above the
factory height. (Elevated units could become
unstable in gusty wind conditions).
Stabilizers may be used on factory height units
when mounted on unstable an uneven surface.
ONE BRACKET PER SIDE (MIN.); FOR EXTRA STABILITY, TWO
BRACKETS PER SIDE, 2" FROM EACH CORNER.
CONCRETE SLAB − USE PLASTIC
PLASTIC ANCHOR (HOLE DRILL
1/4")PLASTIC SLAB − NO PLASTIC
ANCHOR (HOLE DRILL 1/8")
COIL
BASE PAN
CORNER
POST
STABILIZING
BRACKET (18
GAUGE METAL − 2"
WIDTH; HEIGHT AS
REQ’D)
Slab Side Mounting
#10 1/2" LONG
SELF−DRILLING
SHEET METAL
SCREWS
#10 1−1/4" LONG
HEX HD SCREW
AND FLATWASHER
MINIMUM 1
PER SIDE
STABILIZING BRACKET (18
GAUGE METAL − 2" WIDTH;
HEIGHT AS REQ’D); BEND
TO FORM RIGHT ANGLE
FOR EXTRA
STABILITY
Deck Top Mounting
Figure 10. Installing Stabilizer Brackets
New or Replacement Line Set
This section provides information on installation or
replacement of existing line set. If line set are not being
installed then proceed to Brazing Connections on page 11.
If refrigerant lines are routed through a wall, seal and
isolate the opening so vibration is not transmitted to the
building. Pay close attention to line set isolation during
installation of any HVAC system. When properly isolated
from building structures (walls, ceilings. floors), the
refrigerant lines will not create unnecessary vibration and
subsequent sounds. Also, consider the following when
placing and installing a high−efficiency air conditioner.

Page 10
506238−01 06/09
REFRIGERANT LINE SET
Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (braze connections) to the indoor unit
coil (flare or sweat connections). Use Lennox L15 (sweat,
non−flare) series line set, or use field−fabricated refrigerant
lines as listed in Table 2.
Table 2. Refrigerant Line Set
Model
Field Connections Recommended Line Set
Liquid
Line
Suction
Line
Liquid
Line
Suction
Line L15 Line Set
−036 3/8".
(10 mm)
7/8"
(22 mm)
3/8"
(10 mm)
7/8"
(22 mm)
L15−65
15 ft. − 50 ft.
(4.6 m − 15 m)
NOTE  When installing refrigerant lines longer than 50
feet, see the Lennox Refrigerant Piping Design and
Fabrication Guidelines, or contact Lennox Technical
Support Product Applications for assistance. To obtain the
correct information from Lennox, be sure to communicate
the following points:
SModel (XPG20) and size of unit (e.g. −036).
SLine set diameters for the unit being installed as listed
in Table 2 and total length of installation.
SNumber of elbows and vertical rise or drop in the
piping.
MATCHING WITH NEW OR EXISTING INDOOR COIL
AND LINE SET
The RFC1  metering line consisted of a small bore
copper line that runs from condenser to evaporator coil.
Refrigerant is metered into the evaporator by utilizing
temperature/pressure evaporation effects on refrigerant in
the small RFC line. The length and bore of the RFC line
corresponded to the size of cooling unit.
Existing line set of proper size may be reused. If system
was previously HCFC−22 then lines must be flushed (see
Flushing the System on page ). If a Lennox RFC1 liquid line
is existing, it must be replaced.
If the XPG20 must be matched with a proper coil. The only
existing installed coils that could be re−used would be
current coils listed in the XPG20 matchup charts.
INSTALLING LINE SET
Line Set Isolation  This reference illustrates
procedures, which ensure proper refrigerant line set
isolation:
SInstallation of a transition from vertical to
horizontal is illustrated in Figure 11.
SInstallation of line set on vertical runs is illustrated in
Figure 12.
SInstallation of line set on horizontal runs is
illustrated in Figure 13.
NOTE − Similar installation
practices should be used if
line set is to be installed on
exterior of outside wall.
PVC
PIPE FIBERGLASS
INSULATION
CAULK
OUTSIDE
WALL
SUCTION LINE
WRAPPED WITH
ARMAFLEX
LIQUID LINE
IMPORTANT! Refrigerant lines
must not contact structure.
OUTSIDE WALL LIQUID LINE
SUCTION LINE
IMPORTANT - Refriger-
ant lines must not contact
wall.
WOOD BLOCK
BETWEEN STUDS
STRAP
SLEEVE
WOOD BLOCK
STRAP
SLEEVE
WIRE TIE
WIRE TIE
WIRE TIE
INSIDE WALL
Figure 11. Refrigerant Line Set: Transition from
Vertical to Horizontal
ANCHORED HEAVY NYLON
WIRE TIE OR AUTOMOTIVE
MUFFLER-TYPE HANGER
STRAP LIQUID
LINE TO SUCTION
LINE
WALL
STUD
LIQUID LINE
METAL SLEEVE
SUCTION LINE − WRAPPED
IN ARMAFLEX
AUTOMOTIVE
MUFFLER-TYPE HANGER
Figure 12. Refrigerant Line Set: Installing Vertical
Runs (New Construction Shown)

Page 11
XPG20 SERIES
METAL
SLEEVE
STRAPPING
MATERIAL (AROUND
SUCTION LINE
ONLY)
TAPE OR
WIRE TIE
WIRE TIE
(AROUND
SUCTION
LINE ONLY)
FLOOR JOIST OR
ROOF RAFTER
TAPE OR
WIRE TIE
TO HANG LINE SET FROM JOIST OR RAFTER, USE EITHER METAL
STRAPPING MATERIAL OR ANCHORED HEAVY NYLON WIRE TIES.
8 FEET
8 FEET (2.43 METERS)
STRAP THE SUCTION LINE
TO THE JOIST OR RAFTER
AT 8 FEET (2.43 METERS)
INTERVALS THEN STRAP
THE LIQUID LINE TO THE
SUCTION LINE.
FLOOR JOIST OR
ROOF RAFTER
Figure 13. Refrigerant Line Set: Installing
Horizontal Runs
Brazing Connections
WARNING
Polyol ester (POE) oils used with HFC−410A
refrigerant absorb moisture very quickly. It is very
important that the refrigerant system be kept
closed as much as possible. DO NOT remove line
set caps or service valve stub caps until you are
ready to make connections.
WARNING
When using a high pressure gas
such as dry nitrogen to pressurize
a refrigeration or air conditioning
system, use a regulator that can
control the pressure down to 1 or
2 psig (6.9 to 13.8 kPa).
CAUTION
Brazing alloys and flux contain materials which are
hazardous to your health.
Avoid breathing vapors or fumes from brazing
operations. Perform operations only in well
ventilated areas.
Wear gloves and protective goggles or face shield
to protect against burns.
Wash hands with soap and water after handling
brazing alloys and flux.
WARNING
Danger of fire. Bleeding the
refrigerant charge from only the high
side may result in the low side shell
and suction tubing being
pressurized. Application of a brazing
torch while pressurized may result in
ignition of the refrigerant and oil
mixture − check the high and low
pressures before unbrazing.
12
CUT AND DEBUR CAP AND CORE REMOVAL
Cut ends of the refrigerant lines square (free from nicks or
dents). Debur the ends. The pipe must remain round, do not
pinch end of the line.
Remove service cap and core from both the suction and liquid
line service ports.

Page 12
506238−01 06/09
3ATTACHED GAUGES
OUTDOOR
UNIT
LIQUID LINE
SUCTION LINE
LIQUID LINE SERVICE
VALVE
SUCTION LINE
SERVICE
VALVE
ATTACH GAUGES
INDOOR UNIT
SERVICE PORT MUST BE OPEN TO ALLOW EXIT
POINT FOR NITROGEN
AConnect gauge set low pressure side to liquid line service valve.
BConnect gauge set center port to bottle of nitrogen with regulator.
NITROGEN
A
B
HIGH
LOW
USE REGULATOR TO
FLOW NITROGEN AT 1
TO 2 PSIG.
45
WRAP SERVICE VALVE FLOW NITROGEN
To protect components during brazing, wrap a wet cloth around the
liquid line service valve body and copper tube stub and use another
wet cloth underneath the valve body to protect the base paint. Also,
shield the light maroon R−410A sticker.
Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration gauge
set into the valve stem port connection on the liquid line service valve
and out of the valve stem port connection on the suction service valve.
NOTE  The fixed orifice or CTXV metering
device at the indoor unit will allow low pressure
nitrogen to flow through the system.
NITROGEN
HIGH
LOW
USE REGULATOR
TO FLOW
NITROGEN AT 1
TO 2 PSIG.
67
BRAZE LINE SET INSTALL SERVICE PORT CAPS ONLY
Braze the liquid line to the liquid line service
valve. Turn off nitrogen flow.
After all connections have been brazed, disconnect manifold gauge
set from service ports, cool down piping with wet rag and remove all
wrappings. Do not reinstall cores until after evacuation procedure.
Reinstall service caps if desired to close off refrigerant ports.
IMPORTANT − Repeat procedure starting at paragraph 4 for brazing
the suction line to service port valve.
SERVICE PORT
CORE
SERVICE
PORT CAP
SERVICE PORT
WARNING! Allow braze joint to cool before removing the wet rag
from the service valve. (TEMPERATURES ABOVE 250ºF CAN
DAMAGE VALVE SEALS.

Page 13
XPG20 SERIES
Flushing the System
TEFLON RING
FIXED
ORIFICE
(Uncased Coil Shown)
BRASS NUT
LIQUID LINE ASSEMBLY
(INCLUDES STRAINER)
LIQUID LINE ORIFICE HOUSING
DISTRIBUTOR TUBES
DISTRIBUTOR
ASSEMBLY
REMOVE AND
DISCARD
WHITE TEFLON
SEAL (IF PRESENT)
1. On fully cased coils, remove the coil access and plumbing panels.
2. Remove any shipping clamps holding the liquid line and distributor
assembly.
3. Using two wrenches, disconnect liquid line from liquid line orifice
housing. Take care not to twist or damage distributor tubes during
this process.
4. Remove and discard fixed orifice, valve stem assembly if present
and Teflon washer as illustrated above.
5. Use a field−provided fitting to temporary reconnect the liquid line to
the indoor unit’s liquid line orifice housing.
TYPICAL FIXED ORIFICE REMOVAL PROCEDURE TYPICAL TXV REMOVAL PROCEDURE
TWO PIECE
PATCH PLATE
(UNCASED COIL
ONLY)
SUCTION
LINE
DISTRIBUTOR
ASSEMBLY
DISTRIBUTOR
TUBES
LIQUID
LINE
MALE EQUALIZER
LINE FITTING
SENSING
LINE
EQUALIZER
LINE
TXV
TEFLON
RING
(Uncased Coil Shown)
STUB END
TEFLON
RING
SENSING BULB
LIQUID LINE
ORIFICE HOUSING
LIQUID LINE ASSEMBLY
WITH BRASS NUT
1. On fully cased coils, remove the coil access and plumbing panels.
2. Remove any shipping clamps holding the liquid line and distributor assem-
bly.
3. Disconnect the equalizer line from the TXV equalizer line fitting on the suc-
tion line.
4. Remove the suction line sensing bulb.
5. Disconnect the liquid line from the TXV at the liquid line assembly.
6. Disconnect the TXV from the liquid line orifice housing. Take care not to
twist or damage distributor tubes during this process.
7. Remove and discard TXV and the two Teflon rings.
8. Use a field−provided fitting to temporary reconnect the liquid line to the in-
door unit’s liquid line orifice housing.
LOW HIGH
EXISTING
INDOOR
UNIT
GAUGE
MANIFOLD
INVERTED HCFC−22
CYLINDER CONTAINS
CLEAN HCFC−22 TO BE
USED FOR FLUSHING.
LIQUID LINE SERVICE
VALVE
INLET
DISCHARGE
TANK
RETURN
CLOSED
OPENED
RECOVERY
CYLINDER
RECOVERY MACHINE
NEW
OUTDOOR
UNIT
SUCTION LINE
SERVICE
VALVE
SUCTION
LIQUID
1
1. Inverted HCFC−22 cylinder with clean refrigerant to the suction
service valve.
2. HCFC−22 gauge set (low side) to the liquid line valve.
3. HCFC−22 gauge set center port to inlet on the recovery machine.
with an empty recovery tank to the gauge set.
4. Connect recovery tank to recovery machines per machine
instructions.
CONNECT GAUGE SET AND EQUIPMENT FOR
FLUSHING PROCEDURE
B
1
2
3
4
Remove the existing HCFC−22 refrigerant flow control orifice or thermal expansion valve from the indoor coil before flushing the line set. The existing indoor
unit HCFC−22 metering device cannot be use with HFC−410A refrigerant and may prevent proper flushing.
A
B
OR
CFLUSHING LINE SET
1. Set the recovery machine for liquid recovery and start the recovery ma-
chine. Open the gauge set valves to allow the recovery machine to pull
a vacuum on the existing system line set and indoor unit coil.
2. Invert the cylinder of clean HCFC−22 and open its valve to allow liquid re-
frigerant to flow into the system through the suction line valve. Allow the
refrigerant to pass from the cylinder and through the line set and the in-
door unit coil before it enters the recovery machine.
3. After all of the liquid refrigerant has been recovered, switch the recovery
machine to suction recovery so that all of the HCFC−22 suction is recov-
ered. Allow the recovery machine to pull a vacuum on the system.
4. Close the valve on the inverted HCFC−22 drum and the gauge set valves.
Pump the remaining refrigerant out of the recovery machine and turn the
machine off.
NOTE The line set and indoor unit coil must be flushed with at least the
same amount of clean refrigerant that previously charged the system. Check
the charge in the flushing cylinder before proceeding.

Page 14
506238−01 06/09
1. Attach the suction line sensing bulb in the proper orientation as illus-
trated to the right using the clamp and screws provided.
NOTE  Insulating the sensing bulb once installed may be required
when the bulb location is external to the coil casing.
2. Connect the equalizer line from the CTXV to the equalizer suction port
on the suction line. Finger tighten the flare nut plus 1/8 turn (7 ft−lbs)
as illustrated below.
The CTXV unit can be installed internal or external to the indoor coil. In applications where an uncased coil is being
installed in a field−provided plenum, install the CTXV in a manner that will provide access for field servicing of the CTXV.
Refer to below illustration for reference during installation of CTXV unit.
TYPICAL CHECK THERMAL EXPANSION VALVE (CTXV) INSTALLATION PROCEDURE
D
TWO PIECE
PATCH PLATE
(UNCASED COIL
ONLY)
SUCTION
LINE
LIQUID LINE
ORIFICE
HOUSING
DISTRIBUTOR
TUBES
LIQUID
LINE
MALE EQUALIZER LINE
FITTING (SEE
EQUALIZER LINE
INSTALLATION FOR
FURTHER DETAILS)
SENSING
LINE
EQUALIZER
LINE
CTXV
TEFLON
RING
(Uncased Coil Shown)
SENSING BULB INSULATION IS
REQUIRED IF MOUNTED EXTERNAL
TO THE COIL CASING. SENSING
BULB INSTALLATION FOR BULB
POSITIONING.
STUB END
TEFLON
RING
LIQUID LINE ASSEMBLY
WITH BRASS NUT
DISTRIBUTOR
ASSEMBLY
This outdoor unit is designed for use in systems that use CTXV metering device. See the Lennox XPG20 Engineering Handbook for approved
CTXV kit match−ups and application information.
1. Remove the field−provided fitting that temporary reconnected the
liquid line to the indoor unit’s distributor assembly.
2. Install one of the provided Teflon rings around the stubbed end of
the CTXV and lightly lubricate the connector threads and expose
surface of the Teflon ring with refrigerant oil.
3. Attach the stubbed end of the CTXV to the liquid line orifice hous-
ing. Finger tighten and use an appropriately sized wrench to turn an
additional 1/2 turn clockwise as illustrated in the figure above, or
20 ft−lb.
4. Place the remaining Teflon washer around the other end of the
CTXV. Lightly lubricate connector threads and expose surface of
the Teflon ring with refrigerant oil.
5. Attach the liquid line assembly to the CTXV. Finger tighten and use
an appropriately sized wrench to turn an additional 1/2 turn clock-
wise as illustrated in the figure above or 20 ft−lb.
ON 7/8" AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O’CLOCK
POSITION. NEVER MOUNT ON
BOTTOM OF LINE.
12
ON LINES SMALLER THAN 7/8",
MOUNT SENSING BULB AT
EITHER THE 3 OR 9 O’CLOCK
POSITION.
12
BULB
SUCTION
LINE
SUCTION
LINE
NOTE Never mount on bottom of line.
BULB
BULB
BULB
SUCTION LINE
FLARE NUT
COPPER FLARE
SEAL BONNET
MALE BRASS EQUALIZER
LINE FITTING
FLARE SEAL
CAP
OR
1
2
3
4
5
6
7
8
9
10
11 12 1/2 TURN
NOTE − To prevent any possibility of water damage, properly insulate
all parts of the CTXV assembly that may sweat due to temperature differ-
ences between the valve and its surrounding ambient temperatures.
SENSING BULB INSTALLATION
EQUALIZER LINE INSTALLATION
1
2
3
4
5
6
7
8
9
10
11 12
1/8 TURN
1. Remove and discard either the flare seal cap or flare nut with copper
flare seal bonnet from the equalizer line port on the suction line as illus-
trated in the figure to the right.
2. Remove and discard either the flare seal cap or flare nut with copper
flare seal bonnet from the equalizer line port on the suction line as illus-
trated in the figure to the right.

Page 15
XPG20 SERIES
CAUTION
This procedure should not be performed on
systems which contain contaminants (Example:
compressor burn out).
IMPORTANT
If this unit is being matched with an approved line
set or indoor unit coil which was previously
charged with mineral oil, or if it is being matched
with a coil which was manufactured before
January of 1999, the coil and line set must be
flushed prior to installation. Take care to empty all
existing traps. Polyol ester (POE) oils are used in
Lennox units charged with HFC−410A refrigerant.
Residual mineral oil can act as an insulator,
preventing proper heat transfer. It can also clog
the expansion device, and reduce the system
performance and capacity.
Failure to properly flush the system per the
instructions below will void the warranty.
IMPORTANT
The Environmental Protection Agency (EPA)
prohibits the intentional venting of HFC refrigerants
during maintenance, service, repair and disposal of
appliance. Approved methods of recovery,
recycling or reclaiming must be followed.
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.
Leak Testing the System
WARNING
Fire, Explosion and Personal Safety
Hazard.
Failure to follow this warning could
result in damage, personal injury or
death.
Never use oxygen to pressurize or
purge refrigeration lines. Oxygen,
when exposed to a spark or open
flame, can cause damage by fire and/
or an explosion, that could result in
personal injury or death.
IMPORTANT
Leak detector must be capable of sensing HFC
refrigerant.
WARNING
When using a high pressure gas such
as dry nitrogen to pressurize a
refrigeration or air conditioning
system, use a regulator that can
control the pressure down to 1 or 2
psig (6.9 to 13.8 kPa).
WARNING
Refrigerant can be harmful if it is inhaled.
Refrigerant must be used and recovered
responsibly.
Failure to follow this warning may result in personal
injury or death.

Page 16
506238−01 06/09
TO SUCTION
SERVICE VALVE
HFC−410A
MANIFOLD GAUGE SET
OUTDOOR UNIT
1
2
HIGH
LOW
NITROGEN
NOTE Normally, the high pressure hose is connected to the liquid line port. However, connecting it to the suction port better protects the manifold
gauge set from high pressure damage.
1. Connect an HFC−410A manifold gauge set high pressure hose to the suction valve service port.
2. With both manifold valves closed, connect the cylinder of HFC−410A refrigerant to the center port of the manifold gauge set.
NOTE  Later in the procedure, the HFC−410A container will be replace by the nitrogen container.
3. With both manifold valves closed, connect the cylinder of HFC−410A refrigerant to the center port of the manifold gauge set. Open the valve on
the HFC−410A cylinder (suction only).
4. Open the high pressure side of the manifold to allow HFC−410A into the line set and indoor unit. Weigh in a trace amount of HFC−410A. [A trace
amount is a maximum of two ounces (57 g) refrigerant or three pounds (31 kPa) pressure]. Close the valve on the HFC−410A cylinder and the valve
on the high pressure side of the manifold gauge set. Disconnect the HFC−410A cylinder.
5. Connect a cylinder of dry nitrogen with a pressure regulating valve to the center port of the manifold gauge set.
6. Adjust dry nitrogen pressure to 150 psig (1034 kPa). Open the valve on the high side of the manifold gauge set in order to pressurize the line set and
the indoor unit.
7. After a few minutes, open one of the service valve ports and verify that the refrigerant added to the system earlier is measurable with a leak detector.
8. After leak testing disconnect gauges from service ports.
USE REGULATOR TO
FLOW NITROGEN AT 1
TO 2 PSIG.
LEAK TESTING THE SYSTEM
After the line set has been connected to the indoor unit and air conditioner, check the line set connections and indoor unit for leaks. Use
the following procedure to test for leaks:

Page 17
XPG20 SERIES
Evacuating the System
NOTE Remove cores from service valves (if not already done).
1. Open both manifold valves and start the vacuum pump.
2. Evacuate the line set and indoor unit to an absolute pressure of 23,000 microns (29.01 inches of mercury).
NOTE During the early stages of evacuation, it is desirable to close the manifold gauge valve at least once. A rapid rise in pressure indicates
a relatively large leak. If this occurs, repeat the leak testing procedure.
NOTE  The term absolute pressure means the total actual pressure within a given volume or system, above the absolute zero of pressure. Abso-
lute pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.
3. When the absolute pressure reaches 23,000 microns (29.01 inches of mercury), close the manifold gauge valves, turn off the vacuum pump
and disconnect the manifold gauge center port hose from vacuum pump. Attach the manifold center port hose to a dry nitrogen cylinder with
pressure regulator set to 150 psig (1034 kPa) and purge the hose. Open the manifold gauge valves to break the vacuum in the line set and indoor
unit. Close the manifold gauge valves.
4. Shut off the dry nitrogen cylinder and remove the manifold gauge hose from the cylinder. Open the manifold gauge valves to release the dry
nitrogen from the line set and indoor unit.
5. Reconnect the manifold gauge to the vacuum pump, turn the pump on, and continue to evacuate the line set and indoor unit until the absolute
pressure does not rise above 500 microns (29.9 inches of mercury) within a 20−minute period after shutting off the vacuum pump and closing
the manifold gauge valves.
6. When the absolute pressure requirement above has been met, disconnect the manifold hose from the vacuum
pump and connect it to an upright cylinder of HFC−410A refrigerant. Open the manifold gauge valve 1 to 2 psig
in order to release the vacuum in the line set and indoor unit.
7. Perform the following:
AClose manifold gauge valves.
BShut off HFC−410A cylinder.
CReinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core
tool while maintaining a positive system pressure.
DReplace the stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as illustrated.
OUTDOOR UNIT
TO SUCTION
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
MICRON GAUGE
VACUUM PUMP
A34000 1/4 SAE
TEE WITH
SWIVEL
COUPLER 50
MANIFOLD GAUGE SET
HFC−410A
RECOMMEND MINIMUM
3/8" HOSE
AConnect low side of manifold gauge set with 1/4 SAE in−line tee to
suction line service valve
BConnect high side of manifold gauge set to liquid line service valve
CConnect micron gauge available connector on the 1/4 SAE in−line tee.
DConnect the vacuum pump (with vacuum gauge) to the center port of
the manifold gauge set. The center port line will be used later for both
the HFC−410A and nitrogen containers.
A
B
C
D
HIGHLOW
1
2
3
4
5
6
7
8
9
10
11 12
1/6 TURN
NITROGEN
USE REGULATOR TO
FLOW NITROGEN AT 1
TO 2 PSIG.
Evacuating the system of non−condensables is critical for proper operation of the unit. Non−condensables are defined as any gas that will not
condense under temperatures and pressures present during operation of an air conditioning system. Non−condensables and water suction
combine with refrigerant to produce substances that corrode copper piping and compressor parts.

Page 18
506238−01 06/09
IMPORTANT
Use a thermocouple or thermistor electronic
vacuum gauge that is calibrated in microns. Use an
instrument capable of accurately measuring down
to 50 microns.
WARNING
Danger of Equipment Damage. Avoid deep
vacuum operation. Do not use compressors to
evacuate a system. Extremely low vacuums can
cause internal arcing and compressor failure.
Damage caused by deep vacuum operation will
void warranty.
Servicing Units Delivered Void of Charge
If the outdoor unit is void of refrigerant, clean the system
using the procedure described below.
1. Use nitrogen to pressurize the system and check for
leaks. Repair all leaks.
2. Evacuate the system to remove as much of the
moisture as possible.
3. Use nitrogen to break the vacuum and install a new
filter drier in the system.
4. Evacuate the system again. Then, weigh the
appropriate amount of HFC−410A refrigerant as listed
on unit nameplate into the system.
5. Monitor the system to determine the amount of
moisture remaining in the oil. It may be necessary to
replace the filter drier several times to achieve the
required dryness level. If system dryness is not
verified, the compressor will fail in the future.
Electrical
In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).
WARNING
Electric Shock Hazard. Can cause
injury or death. Unit must be
grounded in accordance with national
and local codes.
Line voltage is present at all
components when unit is not in
operation on units with single-pole
contactors. Disconnect all remote
electric power supplies before
opening access panel. Unit may have
multiple power supplies.
Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.
230VAC SUPPLY VOLTAGE
The XPG20 outdoor unit is rated for 230VAC applications
only.
24VAC TRANSFORMER
24VAC for the heat pump is provided by the indoor unit
transformer.
24VDC SOLAR CIRCUIT
This circuit is used for outdoor fan solar assisted operation.
See Figure 17 for specific connection and hardware
requirements for installation.
SERVICE
DISCONNECT
SWITCH
MAIN FUSE BOX/BREAKER
PANEL
Refer to the unit nameplate for minimum circuit ampacity, and
maximum fuse or circuit breaker (HACR per NEC). Install power
wiring and properly sized disconnect switch.
1
NOTE Units are approved for use only with copper conductors.
Ground unit at disconnect switch or to an earth ground.
SIZE CIRCUIT AND INSTALL DISCONNECT
SWITCH
DC SOLAR
DISCONNECT
SWITCH
TO INSTALLED SOLAR MODULE
WEATHER PROOF JUNCTION BOX
s
NOTE 24VAC, Class II circuit connections are made in the
control box.
2
Install room thermostat (ordered separately) on an inside wall
approximately in the center of the conditioned area and 5 feet (1.5m)
from the floor. It should not be installed on an outside wall or where it
can be affected by sunlight or drafts.
THERMOSTAT
5 FEET (1.5M)
INSTALL THERMOSTAT

Page 19
XPG20 SERIES
3
Install low voltage wiring from outdoor to indoor unit and
from thermostat to indoor unit as illustrated.
TYPICAL CONTROL WIRING CONNECTIONS
R
W3
C
G
R
C
Y2
Y1
W1
O
OUTDOOR UNIT INDOOR UNIT TB1
R
O
THERMOSTAT
W2
Y2
Y1
O
Y2
Y1
G
C
W1
W1
Y2
OUT
L
L
DS
DS
NOTE For proper voltages, select thermostat wire (control wires) gauge
per table above.
WIRE RUN LENGTH AWG# INSULATION TYPE
LESS THAN 100’ (30 METERS) 18 TEMPERATURE RATING
MORE THAN 100’ (30 METERS) 16 35ºC MINIMUM. NOTE Wire tie provides low voltage wire strain relief and to maintain
separation of field−installed low and high voltage circuits.
ARun 24VAC control wires through hole with grommet.
BMake 24VAC thermostat wire connections.
NOTE Do not bundle any excess 24VAC control wires inside control box.
4ROUTE THERMOSTAT WIRES
A
B
DEFROST CONTROL
BOARD (DCB)
CONTROL BOX
HOLE
NOTE Any excess high voltage field wiring should be
trimmed and secured away from any low voltage field wiring. To
facilitate a conduit, a cutout is located in the bottom of the
control box. Connect conduit to the control box using a proper
conduit fitting.
5ROUTE HIGH VOLTAGE AND GROUND WIRES
CONTROL BOX
PIPING PANEL
HIGH VOLTAGE
CONDUIT
HOLE
GROUND
LUG CONTACTOR
WATERTIGHT
CONDUIT
FITTING
WATERTIGHT
FLEXIBLE
CONDUIT
TO AC
DISCONNECT
BOX
ACCESS VIEW
ELECTRICAL INLET
(HIGH VOLTAGE)
SOLAR MOD-
ULE WIRING
ELECTRICAL INLET
(CONTROL WIRING
− LOW VOLTAGE)
WIRING ENTRY POINTS

Page 20
506238−01 06/09
Figure 14. Typical XPG20 Wiring
Solar Module Setup and Connections
OVERVIEW
The Lennox SunSourcetComfort System solar assisted
heat pump utilizes a single solar module to offset the utility
power consumed by the outdoor fan. The heart of the
SunSource is a 24VDC Electronically Commutated Motor
(ECM) that is coupled directly to the AC powered ECM
motor used in the XPG20 heat pump. This DC motor is
wired directly to the output of the single solar module.
When the solar module produces electricity and the heat
pump fan is running, the DC motor applies a torque on the
fan shaft and reduces the load of the AC motor. The AC
motor inverter control senses this reduction in load and
realize that the AC motor does not have to work as hard to
achieve its desired speed. Thus it reduces the power the
AC motor consumes. The more sunlight that is available
the more assist the DC motor will produce, and the less
utility power is consumed by the AC motor.
SOLAR MODULE MOUNTING AND TILT ANGLE
The solar module should be mounted in a location where it
will receive maximum sunlight throughout the year. When
choosing a site, avoid trees, buildings or obstructions
which could cast shadows on the solar module especially
during the winter months when the arc of the sun is lowest
over the horizon.