Lennox XP21 Series Manual

Page 1 2012 Lennox Industries Inc.
Corp. 1031−L7
Revised August 17, 2012
XP21
INSTALLATION AND SERVICE
PROCEDURE
Service Literature
Dave Lennox Signature®Collection XP21 Series Units
NOTICE
A thermostat is not included and must be ordered
separately.
The Lennox icomfort thermostat must be used in
communicating applications.
In non−communicating applications, the Lennox
ComfortSense®7000 thermostat may be used, as well
as other non−communicating thermostats.
In all cases, setup is critical to ensure proper system
operation.
Field wiring examples for non−communicating
applications begin on page 22.
See the icomfortthermostat Quick Start Guide for
communicating and partial communicating field wiring
connections.
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause personal injury, loss of life, or
damage to property.
Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.
IMPORTANT
The Clean Air Act of 1990 bans the intentional venting of
refrigerant (CFCs, HCFCs AND HFCs) as of July 1, 1992.
Approved methods of recovery, recycling or reclaiming
must be followed. Fines and/or incarceration may be
levied for noncompliance.
TABLE OF CONTENTS
I. OVERVIEW
Model Number Identification 2. . . . . . . . . . . . . . . . . . . .
Typical Serial Number Identification 2. . . . . . . . . . . . . .
Specifications 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Data 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Dimensions 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Unit Parts Arrangement 5. . . . . . . . . . . . . . . . .
Operating Gauge Set 6. . . . . . . . . . . . . . . . . . . . . . . . . .
General 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II. INSTALLATION
Unit Placement 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing and Installing Panels 11. . . . . . . . . . . . . . . . .
New or Replacement Line Set 12. . . . . . . . . . . . . . . . . .
Brazing Connections 14. . . . . . . . . . . . . . . . . . . . . . . . . . .
Flushing the System 17. . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing the System 19. . . . . . . . . . . . . . . . . . . . . . .
Evacuating the System 19. . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Field Control Wiring 24. . . . . . . . . . . . . . . . . . . . . . . . . . .
Servicing Unit Delivered Void of Charge 26. . . . . . . . . .
Unit Start−Up 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Refrigerant 26. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Handler / Indoor Coil Match ups and Targeted
Subcooling Values 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating and Temperature Pressures 30. . . . . . . . . .
III. SYSTEM OPERATION AND SERVICE
OUTDOOR CONTROL − PART NUMBER 101796−XX
Heat Pump Control (A175) Jumpers and Terminals 31
System Status, Fault and Lockout LED Codes 33. . . .
Component Field Configuration and
Troubleshooting 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OUTDOOR CONTROL − PART NUMBER 103369−XX
Jumpers and Links 47. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Unit 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7−Segment Alert and System Status Codes 51. . . . . . .
Reconfiguring Outdoor Control using icomfort
Thermostat 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPLICABLE TO ALL VERSIONS
Compressor Information and Testing 57. . . . . . . . . . . . .
System Overview 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrost System 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SunSource®Home Energy System 67. . . . . . . . . . . . . .
Checklists 68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Wiring Diagrams 69. . . . . . . . . . . . . . . . . . . . . . . . . .
Factory Wiring Diagrams 72. . . . . . . . . . . . . . . . . . . . . . .
Unit Sequence of Operations 75. . . . . . . . . . . . . . . . . . .

Page 2
XP21
I. OVERVIEW
Model Number identification
P 21 XXX− −
Unit Type
P = Heat Pump
Series
Nominal Cooling Capacity
024 = 2 tons
036 = 3 tons
048 = 4 tons
060 = 5 tons
Minor Revision Number
230
Voltage
230 = 208/230V−1ph−60hz
Refrigerant Type
X = R−410A
X−02
Typical Serial Number Identification
8 09 C
Year Code
08 = 2008
09 = 2009
10 = 2010
Month Code
A = January
B = February
C = March
05716
5 (or 6) Digit Unique Number
Location Code
19 = Saltillo, Mexico
58 = Marshalltown, IA
5
Specifications
Model Number
Unit Outdoor Fan
Sound Rating Number
(dB)1Factory Refrigerant Charge2Number of Blades Diameter − inches.
XP21−024−230−01, −02, −03, −04, −05 67 11 lbs. 0 oz. 5 26.1
Model Number
Unit Outdoor Fan
Sound Rating Number
(dB)1Factory Refrigerant Charge2Number of Blades Diameter − inches.
XP21−036−230−01, −02, −03, −04 72 11 lbs. 0 oz. 5 26.1
Model Number Sound Rating Number
(dB)1Factory Refrigerant Charge2Number of Blades Diameter − inches.
XP21−048−230−01, −02, −03 73 14 lbs. 0 oz. 5 26.1
XP21−048−230−04 73 13 lbs. 0 oz. 5 26.1
Model Number Sound Rating Number
(dB)1Factory Refrigerant Charge2Number of Blades Diameter − inches.
XP21−060−230−01, −02, −03 73 14 lbs. 4 oz. 5 26.1
XP21−060−230−04 73 13 lbs. 2 oz. 5 26.1
1Tested according to AHRI Standard 270−2008 test conditions.
2Refrigerant charge sufficient for 15 feet length of refrigerant lines.

Page 3 XP21
Electrical Data
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)1
Minimum
Circuity
Ampacity2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−024−230−01,
−02, −03, −04, −05 25 14.9 10.3 51.0 1/3 430 500 2.0
XP21−024−230−05 25 16.6 11.7 58.0 1/3 430 500 2.0
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)1
Minimum
Circuity
Ampacity2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−036−230−01,
−02, −03 35 22.9 16.7 82.0 1/3 525 600 2.0
XP21−036−230−04 35 21.1 15.3 83.0 1/3 525 600 2.0
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)1
Minimum
Circuity
Ampacity2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−048−230−01,
−02, −03 45 28.5 21.2 96.0 1/3 600 675 2.0
XP21−048−230−04 45 28.5 21.2 104.0 1/3 600 675 2.0
208/230V−60 Hz−1 Ph
Model Number
Unit Compressor Condenser Fan
Maximum
Over−
current
Protection
(amps)1
Minimum
Circuity
Ampacity2
Rated Load
Amps (RLA)
Locked
Rotor
Amps
(LRA)
Motor HP Nominal
RPM 1−Stage
Nominal
RPM 2−Stage
Full Load
Amps (FLA)
XP21−060−230−01 50 34.1 25.7 118.0 1/3 625 700 2.0
XP21−060−230−02,
−03 50 30.9 23.1 118.0 1/3 625 700 2.0
XP21−060−230−04 60 38.0 28.8 153.0 1/3 625 700 2.0
1HACR type circuit breaker or fuse.
2Refer to National or Canadian Electrical Code manual to determine wire, fuse and disconnect size requirements.

Page 4
XP21
Unit Dimensions −− Inches (mm)
39−1/2
(1003)
1 (25)
LIQUID LINE
INLET
SIDE VIEW ACCESS VIEW
DISCHARGE AIR
4−5/8
(117)
BASE WITH ELONGATED LEGS
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) (−024 AND −036)
SOLAR MODULE
WIRING
ELECTRICAL INLET
(CONTROL WIRING −
LOW VOLTAGE)
47 (1194) (−048 AND −060)

Page 5 XP21
Typical Unit Parts Arrangement
GROUND LUGS
HIGH VOLTAGE FIELD
CONNECTIONS
CONTACTOR−1POLE
(K1−1)
HEAT PUMP CONTROL (A175)
CAPACITOR (C12)
FAN MOTOR CONTROL (A177)  PULSE−WIDTH
MODULATION (PWM) (ONLY ON UNITS WITH MAIN
CONTROL 101796−XX)
WIRE TIE
RT13 OUTDOOR
AMBIENT
TEMPERATURE
SENSOR
VAPOR VALVE
AND GAUGE
PORT
REVERSING
VALVE
LIQUID LINE BI−FLOW
FILTER DRIER HIGH PRESSURE
SWITCH (S4)
LIQUID VALVE AND
GAUGE PORT
TRUE SUCTION LINE
PORT
LOW PRESSURE
SWITCH (S87)
CRANKCASE HEATER THERMOSTAT (S40)
HR1 CRANKCASE HEATER
COMPRESSOR
MUFFLER
DISCHARGE LINE
CHECK
EXPANSION VALVE
DISCHARGE LINE
TEMPERATURE SENSOR
(RT28)
COIL TEMPERATURE SENSOR (RT21) − ON
RETURN BEND, 12 TUBES UP FROM
BOTTOM (11.50’ UP)
XP21−024 AND −036
XP21−048 AND −060
COIL TEMPERATURE
SENSOR (RT21) − ON
RETURN BEND, 24
TUBES UP FROM
BOTTOM (23.50’ UP)
FAN MOTOR SURGE PROTECTION (ONLY
ON XP21−XXX−230−01 BUILD. STARTING
WITH BUILD −02, SURGE PROTECTION
BUILT INTO FAN MOTOR)
Figure 1. Plumbing, Switches and Sensor Components

Page 6
XP21
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.
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
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 nearby these areas during installation or while
servicing this equipment.
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.
Operating Gauge Set
These instructions are 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 lists
torque values for fasteners.
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.
IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.
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
USING MANIFOLD GAUGE SET
When checking the system charge, only use a manifold
gauge set that features low loss anti−blow back fittings.
Manifold gauge set used with HFC−410A refrigerant sys-
tems 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 or 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 re-
moving refrigerant, flushing, leak testing, evacuating,
checking charge and charging.
Each valve is equipped with a service port which has a fac-
tory−installed valve stem. Figure 2 provides information on
how to access and operating both angle and ball service
valves.
General
The XP21 is a high efficiency residential split−system heat
pump unit, which features a two−stage scroll compressor
and HFC−410A refrigerant. Units are available in 2, 3, 4 and
5−ton sizes. The series is designed for use with an expan-
sion valve only (approved for use with HFC−410A) in the
indoor unit.

Page 7 XP21
(VALVE STEM SHOWN
CLOSED) INSERT HEX
WRENCH HERE
SERVICE PORT CORE
SERVICE PORT CAP
ANGLE−TYPE SERVICE VALVE
(FRONT−SEATED CLOSED)
TO OUTDOOR UNIT
STEM CAP
(VALVE STEM SHOWN OPEN)
INSERT HEX WRENCH HERE
TO INDOOR
UNIT
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
SERVICE VALVES ANGLE AND BALL
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. To open valve,
rotate stem counterclockwise 90°. To close, rotate stem
clockwise 90°.
1
2
3
4
5
6
7
8
9
10
11 12
1/12 TURN
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 set to service port.
3. When testing is completed, replace service port cap and tighten as
follows:
With torque wrench: Finger tighten and
torque cap per table 1.
Without torque wrench: Finger tighten and
use an appropriately sized wrench to turn
an additional 1/6 turn clockwise.
12
3
4
5
6
7
8
9
10
11 12
1/6 TURN
WHEN SERVICE VALVE IS CLOSED,THE SERVICE PORT IS
OPEN TO THE LINE SET AND INDOOR UNIT.
When service valve is OPEN, the service port is
open to linE set, indoor and outdoor unit.
Reinstall Stem Cap:
Stem cap protects the valve stem from damage and serves as the
primary seal. Replace the stem cap and tighten as follows:
With Torque Wrench: Finger tighten and then
torque cap per table 1.
Without Torque Wrench: Finger tighten and
use an appropriately sized wrench to turn an
additional 1/12 turn clockwise.
NOTE  A label with specific torque requirements may be affixed to the stem cap. If the label is present, use the specified torque.
Figure 2. Angle and Ball Service Valves

Page 8
XP21
II. INSTALLATION
Unit Placement
CAUTION
In order to avoid injury, take proper precaution when lift-
ing heavy objects.
See Unit Dimensions on page 3 for sizing mounting slab,
platforms or supports. Refer to figure 3 for mandatory
installation clearance requirements.
POSITIONING CONSIDERATIONS
Consider the following when positioning the unit:
Some 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.
When possible, do not install the unit directly outside
a window. Glass has a very high level of sound trans-
mission. For proper placement of unit in relation to a
window see the provided illustration in figure 5, detail
A.
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 5, de-
tail B.
NOTE  If necessary for stability, anchor unit to slab as de-
scribed in figure 5, detail D.
ELEVATING THE UNIT
Units are outfitted with elongated support feet as illustrated
in figure 5, detail C.
If additional elevation is necessary, raise the unit by ex-
tending the height of the unit support feet. This may be
achieved by using a 2−inch (50.8mm) Schedule 40 female
threaded adapter.
The specified coupling will fit snuggly into the recessed
portion of the feet. Use additional 2−inch (50.8mm) Sched-
ule 40 male threaded adaptors which can be threaded into
the female threaded adaptors to make additional adjust-
ments to the level of the unit.
NOTE  Keep the height of extenders short enough to en-
sure a sturdy installation. If it is necessary to extend
further, consider a different type of field−fabricated frame-
work that is sturdy enough for greater heights.
CONTROL PANEL
ACCESS
LOCATION
6 (152)
36 (914)
12 (305) 30 (762)
LINE SET
CONNECTIONS
24 (610)
LINE SET
CONNECTIONS
ACCESS PANEL
REAR VIEW OF UNIT
48 (1219)
MINIMUM CLEARANCE BETWEEN
TWO UNITS
CLEARANCE ON ALL SIDES  INCHES (MILLIMETERS)
ACCESS PANEL
MINIMUM CLEARANCE
ABOVE UNIT
NOTES:
CLEARANCE TO ONE OF THE
OTHER THREE SIDES MUST BE 36
INCHES (914MM).
CLEARANCE TO ONE OF THE
REMAINING TWO SIDES MAY BE 12
INCHES (305MM) AND THE FINAL
SIDE MAY BE 6 INCHES (152MM).
Figure 3. Installation Clearances

Page 9 XP21
STABILIZING UNIT ON UNEVEN SURFACES
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.
1. Remove two side louvered panels to expose the unit
base.
2. Install the brackets as illustrated in figure 5, detail D us-
ing conventional practices.
3. Replace the panels after installation is complete.
ROOF MOUNTING
NOTICE
Roof Damage!
This system contains both refrigerant and oil. Some
rubber roofing material may absorbed oil and cause the
rubber to swell when it comes into contact with oil. The
rubber will then bubble and could cause leaks. Protect
the roof surface to avoid exposure to refrigerant and oil
during service and installation. Failure to follow this
notice could result in damage to roof surface.
Install the unit a minimum of six inches (152 mm) above the
roof surface to avoid ice build−up around the unit. Locate
the unit above a load bearing wall or area of the roof that
can adequately support the unit. Consult local codes for
rooftop applications.
If unit coil cannot be mounted away from prevailing winter
winds, a wind barrier should be constructed. Size barrier at
least the same height and width as outdoor unit. Mount bar-
rier 24 inches (610 mm) from the sides of the unit in the
direction of prevailing winds.
24"
(610)
WIND BARRIER
PREVAILING WINTER
WINDS
INLET AIR
INLET AIR
INLET AIR
Figure 4. Rooftop Application and Wind Barrier

Page 10
XP21
LEG DETAIL
BASE
2" (50.8MM) SCH 40
FEMALE THREADED
ADAPTER
ONE BRACKET PER SIDE (MIN.); FOR EXTRA STABILITY, TWO
BRACKETS PER SIDE, 2" (50.8MM) FROM EACH CORNER.
CONCRETE SLAB  USE TWO PLASTIC
ANCHORS (HOLE DRILL 1/4")
COIL
BASE PAN
CORNER POST
STABILIZING BRACKET (18 GAUGE
METAL  2" WIDTH; HEIGHT AS
REQUIRED)
Slab Side Mounting
#10 1/2" LONG SELF−DRILLING
SHEET METAL SCREWS
#10 1−1/4" LONG HEX HD SCREW
AND FLAT WASHER
MINIMUM ONE
PER SIDE
STABILIZING BRACKET (18 GAUGE METAL
 2" (50.8MM) WIDTH; HEIGHT AS
REQUIRED); BEND TO FORM RIGHT ANGLE
FOR EXTRA
STABILITY
Deck Top Mounting
Elevated Slab Mounting using Feet
Extenders
Stabilizing Unit on Uneven Surfaces
WOOD OR PLASTIC SLAB  NO PLASTIC ANCHOR
(HOLE DRILL 1/8")
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
Outside Unit Placement
Slab Mounting at Ground Level
SAME FASTENERS AS
SLAB SIDE MOUNTING.
IMPORTANT  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.
DETAIL A DETAIL B
DETAIL C DETAIL D
2" (50.8MM) SCH 40
MALE THREADED
ADAPTER
USE ADDITIONAL 2" SCH 40 MALE THREADED ADAPT-
ERS WHICH CAN BE THREADED INTO THE FEMALE
THREADED ADAPTERS TO MAKE ADDITIONAL AD-
JUSTMENTS TO THE LEVEL OF THE UNIT.
TWO 90° ELBOWS INSTALLED IN LINE SET WILL
REDUCE LINE SET VIBRATION.
INSTALL UNIT AWAY FROM WINDOWS
Figure 5. Placement and Slab Mounting

Page 11 XP21
Removing and Installing Panels
REMOVE 4 SCREWS TO
REMOVE PANEL FOR
ACCESSING COMPRESSOR
AND CONTROLS.
POSITION PANEL WITH HOLES
ALIGNED; INSTALL SCREWS
AND TIGHTEN.
ACCESS PANEL REMOVAL
REMOVAL AND RE−INSTALLATION OF THE
ACCESS PANEL IS AS ILLUSTRATED.
Detail A
Detail B
ROTATE IN THIS DIRECTION; THEN
DOWN TO REMOVE PANEL
SCREW
HOLES
LIP
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
LOUVERED PANEL REMOVAL
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 DETAIL B.
3. MOVE PANEL DOWN UNTIL LIP OF UPPER TAB CLEARS THE TOP SLOT IN CORNER
POST AS ILLUSTRATED IN DETAIL A.
LOUVERED PANEL INSTALLATION
POSITION THE PANEL ALMOST PARALLEL WITH THE UNIT AS ILLUSTRATED IN DETAIL D WITH
THE SCREW SIDE AS CLOSE TO THE UNIT AS POSSIBLE. THEN, IN A CONTINUOUS MOTION:
1. SLIGHTLY ROTATE AND GUIDE THE LIP OF TOP TAB INWARD AS ILLUSTRATED IN DETAIL
AAND C; THEN UPWARD INTO THE TOP SLOT OF THE HINGE CORNER POST.
2. ROTATE PANEL TO VERTICAL TO FULLY ENGAGE ALL TABS.
3. HOLDING THE PANEL’S HINGED SIDE FIRMLY IN PLACE, CLOSE THE RIGHT−HAND SIDE
OF THE PANEL, ALIGNING THE SCREW HOLES.
4. WHEN PANEL IS CORRECTLY POSITIONED AND ALIGNED, INSERT THE SCREWS AND
TIGHTEN.
PANELS
ACCESS AND LOUVERED
IMPORTANT  Do not allow panels to hang on unit by top tab.
Tab is for alignment and not designed to support weight of panel.
IMPORTANT  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.
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
Detail C
Figure 6. Removing and Installing Panels

Page 12
XP21
New or Replacement Line Set
REFRIGERANT LINE SET
This section provides information on installation or replace-
ment of existing line set. If new or replacement line set is
not being installed then proceed to Brazing Connections on
page 14.
IMPORTANT
Lennox highly recommends changing line set when
converting the existing system from HCFC−22 to
HFC−410A.If that is not possible and the line set is the
proper size as reference in table 2, use the procedure
outlined under Flushing the System on page 17.
If refrigerant lines are routed through a wall, then 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 refrig-
erant lines will not create unnecessary vibration and
subsequent sounds. See figure 7 for recommended instal-
lation practices. Also, consider the following when placing
and installing a high−efficiency outdoor unit.
Liquid lines that meter the refrigerant, such as RFC1 liquid
lines, must not be used in this application. Existing line set
of proper size as listed in table 2 may be reused. If system
was previously charged with HCFC−22 refrigerant, then ex-
isting line set must be flushed (see Flushing the System on
page 17).
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit to the indoor unit coil (braze connec-
tions). Use Lennox L15 (sweat, non−flare) series line set, or
field−fabricated refrigerant line sizes as listed in table 2.
Table 2. Refrigerant Line Set
Models Liquid
Line
Vapor/
Suction
Line
L15 Line Set
−024, −036
and−048
3/8 (10) 7/8 (22) L15 line set sizes are
dependent on unit match
up. See XP21 Engineering
Handbook to determine
correct line set sizes.
−060 3/8 (10) 1−1/8 (29) Field Fabricated
NOTE  Some applications may required a field−provided 7/8" to
1−1/8" adapter.
NOTE  When installing refrigerant lines longer than 50
feet, see the Lennox Refrigerant Piping Design and Fab-
rication Guidelines, or contact Lennox Technical Support
Product Applications for assistance. To obtain the correct
information from Lennox, be sure to communicate the fol-
lowing points:
Model (XP21) and size of unit (e.g. −036).
Line set diameters for the unit being installed as listed
in table 2 and total length of installation.
Number of elbows vertical rise or drop in the piping.
IMPORTANT
Mineral oils are not compatible with HFC−410A.If oil must
be added, it must be a Polyol ester oil.
The compressor is charged with sufficient Polyol ester oil
for line set lengths up to 50 feet. Recommend adding oil to
system based on the amount of refrigerant charge in the
system. No need to add oil in system with 20 pounds of re-
frigerant or less. For systems over 20 pounds − add one
ounce of every five pounds of refrigerant.
Recommended topping−off POE oils are Mobil EAL ARC-
TIC 22 CC or ICI EMKARATERL32CF.
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.
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.

Page 13 XP21
ANCHORED HEAVY NYLON
WIRE TIE OR AUTOMOTIVE
MUFFLER-TYPE HANGER
STRAP LIQUID LINE TO
VAPOR LINE
WALL
STUD
LIQUID LINE
NON−CORROSIVE
METAL SLEEVE
VAPOR LINE − WRAPPED
IN ARMAFLEX
AUTOMOTIVE
MUFFLER-TYPE HANGER
REFRIGERANT LINE SET  TRANSITION
FROM VERTICAL TO HORIZONTAL
LINE SET ISOLATION  THE FOLLOWING ILLUSTRATIONS ARE EXAM-
PLES OF PROPER REFRIGERANT LINE SET ISOLATION:
STRAPPING
MATERIAL (AROUND
VAPOR LINE ONLY)
TAPE OR
WIRE TIE
WIRE TIE (AROUND
VAPOR 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 (2.43 METERS)
STRAP THE VAPOR LINE TO THE
JOIST OR RAFTER AT 8 FEET (2.43
METERS) INTERVALS THEN STRAP
THE LIQUID LINE TO THE VAPOR LINE.
FLOOR JOIST OR
ROOF RAFTER
REFRIGERANT LINE SET  INSTALLING
HORIZONTAL RUNS
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
VAPOR LINE WRAPPED
WITH ARMAFLEX
LIQUID
LINE
OUTSIDE WALL LIQUID LINE
VAPOR LINE
WOOD BLOCK
BETWEEN STUDS
STRAP
WOOD BLOCK
STRAP
SLEEVE
WIRE TIE
WIRE TIE
WIRE TIE
INSIDE WALL
REFRIGERANT LINE SET  INSTALLING
VERTICAL RUNS (NEW CONSTRUCTION SHOWN)
INSTALLATION
LINE SET
NOTE  INSULATE LIQUID LINE WHEN IT IS ROUTED THROUGH AREAS
WHERE THE SURROUNDING AMBIENT TEMPERATURE COULD BECOME
HIGHER THAN THE TEMPERATURE OF THE LIQUID LINE OR WHEN
PRESSURE DROP IS EQUAL TO OR GREATER THAN 20 PSIG.
NON−CORROSIVE
METAL SLEEVE
IMPORTANT  Refrigerant lines must not contact structure.
NON−CORROSIVE
METAL SLEEVE
8 FEET (2.43 METERS)
IMPORTANT  Refrigerant lines must not contact
wall
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.
Figure 7. Line Set Installation

Page 14
XP21
Brazing Connections
Use the procedures outline in figures 8 and 9 for brazing
line set connections to service valves.
WARNING
Danger of fire. Bleeding the refrigerant
charge from only the high side may result
in pressurization of the low side shell and
suction tubing. Application of a brazing
torch to a pressurized system may result
in ignition of the refrigerant and oil mixture
− Check the high and low pressures
before applying heat.
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.
IMPORTANT
Connect gauge set low pressure side to vapor line
service valve and repeat procedure starting at
paragraph 4 for brazing the liquid line to service port
valve.
IMPORTANT
Allow braze joint to cool before removing the wet rag
from the service valve. Temperatures above 250ºF can
damage valve seals.
IMPORTANT
Use silver alloy brazing rods with 5% minimum silver
alloy for copper−to−copper brazing. Use 45% minimum
alloy for copper−to−brass and copper−to−steel brazing.
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 fire and/or an ex-
plosion, that could result in property
damage, personal injury or death.

Page 15 XP21
ATTACH THE MANIFOLD GAUGE SET FOR BRAZING
LIQUID AND SUCTION LINE SERVICE VALVES
OUTDOOR
UNIT
LIQUID LINE
SUCTION LINE
LIQUID LINE SERVICE
VALVE
SUCTION LINE
SERVICE VALVE
ATTACH
GAUGES
INDOOR
UNIT
SUCTION SERVICE PORT MUST BE OPEN AND
SERVICE PORT CORE REMOVED TO ALLOW
EXIT POINT FOR NITROGEN FLOW
AConnect gauge set low pressure side to liquid line
service valve (service port).
BConnect gauge set center port to bottle of nitrogen
with regulator.
CWith valve core removed from the suction line service
port, nitrogen flow will have an exit point.
NITROGEN
HIGH
LOW
B
A
C
PIPING PANEL REMOVAL AND PREPARING LINE
SET
CAP AND CORE REMOVAL
Remove piping panel for easier access to service valves. Cut ends
of the refrigerant lines square (free from nicks or dents) and debur
the ends. The pipe must remain round. Do not crimp end of the line.
Remove service cap and core from both the suction and liquid line
service ports.
12
LIQUID LINE SERVICE VALVE
SERVICE PORT
CORE
SERVICE PORT CAP
SERVICE PORT
CORE
SERVICE
PORT CAP
CUT AND DEBUR
LINE SET SIZE MATCHES
SERVICE VALVE CONNECTION
COPPER TUBE
STUB
SERVICE VALVE
CONNECTION
REFRIGERANT LINE
DO NOT CRIMP SERVICE
VALVE CONNECTOR WHEN
PIPE IS SMALLER THAN
CONNECTION
REDUCER
3
SUCTION LINE SERVICE
VALVE
LINE SET SIZE IS SMALLER
THAN CONNECTION
Figure 8. Brazing Procedures

Page 16
XP21
BRAZE LINE SET
Water saturated cloths must remain water saturated
throughout the brazing and cool−down process.
6
After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water saturated cloths to both
services valves to cool piping. Once piping is cool, remove all water saturated cloths. Refer to the unit installation instructions for the next step in
preparing the unit.
PREPARATION FOR NEXT STEP
7
WRAP SERVICE VALVES
To help protect service valve seals during brazing, wrap water saturated cloths around service valve bodies and copper tube stubs. Use
additional water saturated cloths underneath the valve body to protect the base paint.
4
FLOW NITROGEN
Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration
gauge set into the valve stem port connection on the liquid service
valve and out of the suction / vapor valve stem port. See steps 3A,
3B and 3C on previous page and below for manifold gauge setup.
5
SUCTION / VAPOR LINE
WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.
WARNING
1. FIRE, PERSONAL INJURY, OR PROPERTY
DAMAGE will result if you do not wrap a water
saturated cloth around both liquid and suction line
service valve bodies and copper tube stub while
brazing in the line set! The braze, when complete,
must be quenched with water to absorb any
residual heat.
2. Do not open service valves until refrigerant lines
and indoor coil have been leak−tested and
evacuated. Refer to procedures provided in this
supplement.
LIQUID LINE
WATER SATURATED
CLOTHS
WATER SATURATED CLOTHS
ABraze liquid line to liquid line service valve.
BBraze suction / vapor line to suction / vapor service
valve.
6A
6B
SUCTION / VAPOR SERVICE PORT
MUST BE OPEN AND SERVICE PORT
CORE REMOVED TO ALLOW EXIT
POINT FOR NITROGEN FLOW
IMPORTANT  Allow braze joint to cool. Apply
additional water saturated cloths to help cool
brazed joints. Do not remove water saturated
cloths until piping has cooled. Temperatures
above 250ºF will damage valve seals.
Figure 9. Brazing Procedures (Continued)

Page 17 XP21
Flushing the System
SENSING
LINE
TEFLON®RING
FIXED ORIFICE
BRASS NUT
LIQUID LINE ASSEMBLY
(INCLUDES STRAINER)
LIQUID LINE ORIFICE HOUSING
DISTRIBUTOR TUBES
DISTRIBUTOR
ASSEMBLY
REMOVE AND DISCARD
WHITE TEFLON®SEAL
(IF PRESENT)
AON FULLY CASED COILS, REMOVE THE COIL ACCESS AND PLUMBING
PANELS.
BREMOVE ANY SHIPPING CLAMPS HOLDING THE LIQUID LINE AND DIS-
TRIBUTOR ASSEMBLY.
CUSING TWO WRENCHES, DISCONNECT LIQUID LINE FROM LIQUID LINE
ORIFICE HOUSING. TAKE CARE NOT TO TWIST OR DAMAGE DISTRIBU-
TOR TUBES DURING THIS PROCESS.
DREMOVE AND DISCARD FIXED ORIFICE, VALVE STEM ASSEMBLY IF
PRESENT AND TEFLON®WASHER AS ILLUSTRATED ABOVE.
EUSE A FIELD−PROVIDED FITTING TO TEMPORARY RECONNECT THE
LIQUID LINE TO THE INDOOR UNIT’S LIQUID LINE ORIFICE HOUSING.
TYPICAL EXISTING FIXED ORIFICE
REMOVAL PROCEDURE (UNCASED COIL
SHOWN)
TYPICAL EXISTING EXPANSION VALVE
REMOVAL PROCEDURE (UNCASED COIL
SHOWN)
TWO PIECE PATCH PLATE
(UNCASED COIL ONLY)
VAPOR
LINE
DISTRIBUTOR
ASSEMBLY
DISTRIBUTOR
TUBES
LIQUID
LINE
MALE EQUALIZER
LINE FITTING
EQUALIZER
LINE
CHECK
EXPANSION
VALVE
TEFLON®
RING
STUB END
TEFLON®
RING
SENSING BULB
LIQUID LINE
ORIFICE
HOUSING
LIQUID LINE
ASSEMBLY WITH
BRASS NUT
AON FULLY CASED COILS, REMOVE THE COIL ACCESS AND PLUMBING
PANELS.
BREMOVE ANY SHIPPING CLAMPS HOLDING THE LIQUID LINE AND DIS-
TRIBUTOR ASSEMBLY.
CDISCONNECT THE EQUALIZER LINE FROM THE CHECK EXPANSION
VALVE EQUALIZER LINE FITTING ON THE VAPOR LINE.
DREMOVE THE VAPOR LINE SENSING BULB.
EDISCONNECT THE LIQUID LINE FROM THE CHECK EXPANSION VALVE
AT THE LIQUID LINE ASSEMBLY.
FDISCONNECT THE CHECK EXPANSION VALVE FROM THE LIQUID LINE
ORIFICE HOUSING. TAKE CARE NOT TO TWIST OR DAMAGE DISTRIBU-
TOR TUBES DURING THIS PROCESS.
GREMOVE AND DISCARD CHECK EXPANSION VALVE AND THE TWO TEF-
LON®RINGS.
HUSE A FIELD−PROVIDED FITTING TO TEMPORARY RECONNECT THE
LIQUID LINE TO THE INDOOR 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
VAPOR LINE
SERVICE VALVE
VAPOR
LIQUID
1
AINVERTED HCFC−22 CYLINDER WITH CLEAN REFRIGERANT TO THE
VAPOR SERVICE VALVE.
BHCFC−22 GAUGE SET (LOW SIDE) TO THE LIQUID LINE VALVE.
CHCFC−22 GAUGE SET CENTER PORT TO INLET ON THE RECOVERY
MACHINE WITH AN EMPTY RECOVERY TANK TO THE GAUGE SET.
DCONNECT RECOVERY TANK TO RECOVERY MACHINES PER MACHINE
INSTRUCTIONS.
CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE
A
B
C
D
B
OR
FLUSHING LINE SET
ASET THE RECOVERY MACHINE FOR LIQUID RECOVERY AND
START THE RECOVERY MACHINE. OPEN THE GAUGE SET
VALVES TO ALLOW THE RECOVERY MACHINE TO PULL A VACU-
UM ON THE EXISTING SYSTEM LINE SET AND INDOOR UNIT COIL.
BINVERT THE CYLINDER OF CLEAN HCFC−22 AND OPEN ITS VALVE
TO ALLOW LIQUID REFRIGERANT TO FLOW INTO THE SYSTEM
THROUGH THE VAPOR LINE VALVE. ALLOW THE REFRIGERANT
TO PASS FROM THE CYLINDER AND THROUGH THE LINE SET
AND THE INDOOR UNIT COIL BEFORE IT ENTERS THE RECOVERY
MACHINE.
CAFTER ALL OF THE LIQUID REFRIGERANT HAS BEEN RECOV-
ERED, SWITCH THE RECOVERY MACHINE TO VAPOR RECOVERY
SO THAT ALL OF THE HCFC−22 VAPOR IS RECOVERED. ALLOW
THE RECOVERY MACHINE TO PULL DOWN TO 0 THE SYSTEM.
DCLOSE 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.
THE LINE SET AND INDOOR UNIT COIL MUST BE FLUSHED WITH AT
LEAST THE SAME AMOUNT OF CLEAN REFRIGERANT THAT PRE-
VIOUSLY CHARGED THE SYSTEM. CHECK THE CHARGE IN THE
FLUSHING CYLINDER BEFORE PROCEEDING.
LINE SET AND INDOOR COIL (1 OF 2)
1A
2
3
CAUTION This procedure should not be performed on sys-
tems which contain contaminants (Example compressor burn
out.
1B

Page 18
XP21
AATTACH THE VAPOR LINE SENSING BULB IN THE PROPER
ORIENTATION AS ILLUSTRATED TO THE RIGHT USING THE
CLAMP AND SCREWS PROVIDED.
NOTE  CONFIRM PROPER THERMAL CONTACT BETWEEN VA-
POR LINE AND CHECK EXPANSION BULB BEFORE INSULATING
THE SENSING BULB ONCE INSTALLED.
BCONNECT THE EQUALIZER LINE
FROM THE CHECK EXPANSION
VALVE TO THE EQUALIZER VAPOR
PORT ON THE VAPOR LINE. FIN-
GER TIGHTEN THE FLARE NUT
PLUS 1/8 TURN (7 FT−LBS) AS IL-
LUSTRATED BELOW.
THE CHECK EXPANSION VALVE 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 CHECK
EXPANSION VALVE IN A MANNER THAT WILL PROVIDE ACCESS
FOR FIELD SERVICING OF THE CHECK EXPANSION VALVE.
REFER TO BELOW ILLUSTRATION FOR REFERENCE DURING
INSTALLATION OF CHECK EXPANSION VALVE UNIT.
TYPICAL NEW CHECK EXPANSION VALVE INSTALLATION PROCEDURE
TWO PIECE
PATCH PLATE
(UNCASED
COIL ONLY)
VAPOR
LINE
LIQUID LINE
ORIFICE
HOUSING
DISTRIBUTOR
TUBES
LIQUID LINE
MALE EQUALIZER LINE
FITTING (SEE
EQUALIZER LINE
INSTALLATION FOR
FURTHER DETAILS)
SENSING
LINE
EQUALIZER
LINE
CHECK
EXPANSION
VALVE
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 CHECK EXPANSION VALVE METERING DEVICE. SEE THE LENNOX XP21 ENGI-
NEERING HANDBOOK FOR APPROVED CHECK EXPANSION VALVE KIT MATCH−UPS AND APPLICATION INFORMATION.
AREMOVE THE FIELD−PROVIDED FITTING THAT TEMPORARY RECON-
NECTED THE LIQUID LINE TO THE INDOOR UNIT’S DISTRIBUTOR AS-
SEMBLY.
BINSTALL ONE OF THE PROVIDED TEFLON®RINGS AROUND THE
STUBBED END OF THE CHECK EXPANSION VALVE AND LIGHTLY LUBRI-
CATE THE CONNECTOR THREADS AND EXPOSE SURFACE OF THE TEF-
LON®RING WITH REFRIGERANT OIL.
CATTACH THE STUBBED END OF THE CHECK EXPANSION VALVE TO THE
LIQUID LINE ORIFICE HOUSING. FINGER TIGHTEN AND USE AN APPRO-
PRIATELY SIZED WRENCH TO TURN AN ADDITIONAL 1/2 TURN CLOCK-
WISE AS ILLUSTRATED IN THE FIGURE ABOVE, OR 20 FT−LB.
DPLACE THE REMAINING TEFLON®WASHER AROUND THE OTHER END
OF THE CHECK EXPANSION VALVE. LIGHTLY LUBRICATE CONNECTOR
THREADS AND EXPOSE SURFACE OF THE TEFLON®RING WITH RE-
FRIGERANT OIL.
EATTACH THE LIQUID LINE ASSEMBLY TO THE CHECK EXPANSION VALVE.
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.
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
VAPOR LINE
VAPOR LINE
NOTE  NEVER MOUNT ON BOTTOM OF LINE.
BULB
BULB
BULB
VAPOR 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
SENSING BULB INSTALLATION
EQUALIZER LINE INSTALLATION
1
2
3
4
5
6
7
8
9
10
11 12
1/8 TURN
FLUSHING LINE SET AND INDOOR COIL (2 OF 2)
4
AREMOVE AND DISCARD EITHER THE FLARE SEAL CAP OR
FLARE NUT WITH COPPER FLARE SEAL BONNET FROM
THE EQUALIZER LINE PORT ON THE VAPOR LINE AS ILLUS-
TRATED IN THE FIGURE TO THE RIGHT.
BREMOVE AND DISCARD EITHER THE FLARE SEAL CAP OR
FLARE NUT WITH COPPER FLARE SEAL BONNET FROM THE
EQUALIZER LINE PORT ON THE VAPOR LINE AS ILLUS-
TRATED IN THE FIGURE TO THE RIGHT.

Page 19 XP21
INSTALLING ISOLATION GROMMETS
Locate the isolation grommets (provided). Slide grommets
onto vapor and liquid lines. Insert grommets into piping
panel to isolate refrigerant lines from sheet metal edges.
TWO ISOLATION GROMMETS ARE
PROVIDE FOR THE LIQUID AND
SUCTION LINE PIPE PANEL PASS
THROUGH.
LIQUID LINE
SUCTION LINE
REAR VIEW OF UNIT EXTERIOR
PIPING PANEL
Figure 10. Isolation Grommets
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.
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.
Leak Testing the System
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.
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.

Page 20
XP21
TO VAPOR
SERVICE VALVE
HFC−410A
MANIFOLD GAUGE SET
OUTDOOR UNIT
HIGH
LOW
NITROGEN
NOTE  NORMALLY, THE HIGH PRESSURE HOSE IS CONNECTED TO THE LIQUID
LINE PORT. HOWEVER, CONNECTING IT TO THE VAPOR PORT BETTER PROTECTS
THE MANIFOLD GAUGE SET FROM HIGH PRESSURE DAMAGE.
AWITH 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 (VAPOR ONLY).
BOPEN 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.
CCONNECT A CYLINDER OF DRY NITROGEN WITH A PRESSURE REGULATING VALVE TO THE CENTER PORT OF THE MANIFOLD
GAUGE SET.
DADJUST 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.
EAFTER 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.
FAFTER LEAK TESTING DISCONNECT GAUGES FROM SERVICE PORTS.
LINE SET AND INDOOR COIL
AFTER THE LINE SET HAS BEEN CONNECTED TO THE INDOOR AND OUTDOOR UNITS, CHECK THE LINE SET CON-
NECTIONS AND INDOOR UNIT FOR LEAKS. USE THE FOLLOWING PROCEDURE TO TEST FOR LEAKS:
LEAK TEST
ACONNECT AN HFC−410A MANIFOLD GAUGE SET
HIGH PRESSURE HOSE TO THE VAPOR VALVE
SERVICE PORT.
BWITH BOTH MANIFOLD VALVES CLOSED, CONNECT
THE CYLINDER OF HFC−410A REFRIGERANT TO THE
CENTER PORT OF THE MANIFOLD GAUGE SET.
1
CONNECT GAUGE
SET
2TEST FOR LEAKS
A
B
NOTE  LATER IN THE PROCEDURE, THE HFC−410A
CONTAINER WILL BE REPLACED BY THE NITROGEN
CONTAINER.
Figure 11. System Leak Test