Lennox XP21 Series User manual

Page 1
2019 Lennox Industries Inc.
Dallas, Texas, USA
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
General
This XP21 outdoor heat pump is designed for use with
HFC-410A refrigerant only. This unit must be installed with
an approved indoor air handler or coil. See the Lennox
XP21 Product Specifications bulletin (EHB) for approved
indoor component match ups.
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
NOTICE !
For more in-depth information, consult the Installa
tion and Service Procedures manual, available as
Corp.1031-L7 on LennoxPros.com or through the
Technical Support department at 800-453-6669.
INSTALLATION
INSTRUCTIONS
Dave Lennox Signature®
Collection XP21 System
HEAT PUMPS
507217-02
8/2019
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal inju
ry or loss of life.
Installation and service must be performed by a licensed
professional installer (or equivalent) or service agency.
CAUTION
Before attempting to perform any service or mainte
nance, turn the electrical power to unit OFF at discon
nect switch.
STEP 1 -- SETTING THE UNIT -- Clearances
CONTROL
PANEL ACCESS
LOCATION
6 (152)
36 (914)
12 (305) 30 (762)
24
(610) LINE SET
CONNECTIONS
ACCESS PANEL
REAR VIEW OF UNIT
48 (1219)
MINIMUM CLEARANCE BETWEEN TWO UNITS
CLEARANCE ON ALL SIDES — INCHES (MILLIMETERS) MINIMUM CLEARANCE
ABOVE UNIT
NOTES:
Clearance to access panel must be 30
inches (762mm).
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).
NOTICE: Specific applications may require adjustment of the listed installation clearances to provide protection for the unit from
physical damage or to avoid conditions which limit operating efficiency. (Example: Clearances may have to be increased to
prevent snow or ice from falling on the top of the unit. Additional clearances may also be required to prevent air recirculation when
the unit is installed under a deck or in another tight space.)
FIGURE 1

Page 2
UNIT DIMENSIONS - INCHES (MM)
4-5/8
(117)
39-1/2
(1003) 35-1/2
(902)
18-1/2
(470)
8 (203)
1 (25)
4-7/16
(113)
LIQUID LINE
INLET
VAPOR LINE
INLET
ELECTRICAL INLETS
BASE WITH ELONGATED LEGS
SIDE VIEW ACCESS VIEW
DISCHARGE AIR
37 (940) [-024 THRU -036]
47 (1194) [-048 AND -060]
16-7/8
(429)
8-3/4
(222)
26-7/8
(683)
3-3/4 (95)
30-3/4
(781)
3-1/8
(79)
UNIT SUPPORT
FEET

Page 3
XP21 SERIES
STEP 1 -- SETTING THE UNIT (Continued)
-- Unit Placement
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
WARNING
To prevent personal injury, as well as damage to panels,
unit or structure, observe the following:
While installing or servicing this unit, carefully stow all
removed panels so that the panels will not cause injury
to personnel, objects or nearby structures. Also, take
care to store panels where they will not be subject to
damage (e.g., being bent or scratched).
While handling or stowing the panels, consider any
weather conditions (especially wind) that may cause
panels to be blown around and damaged.
NOTICE !
Roof Damage!
This system contains both refrigerant and oil. Some
rubber roofing material may absorb oil, causing the
rubber to degrade. Failure to follow this notice
could result in damage to roof surface.
IMPORTANT !
Exhaust vents from dryers, water heaters and
furnaces should be directed away from the outdoor
unit. Prolonged exposure to exhaust gases and the
chemicals contained within them may cause
condensation to form on the steel cabinet and other
metal components of the outdoor unit. This will
diminish unit performance and longevity.
INSTALL UNIT AWAY
FROM WINDOWS
TWO 90ELBOWS INSTALLED IN LINE SET
WILL REDUCE LINE SET VIBRATION
PLACEMENT
FIGURE 2
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.
GROUND LEVEL
MOUNTING
SLAB
BUILDING
STRUCTURE DISCHARGE AIR
SLAB MOUNTING
FIGURE 3
LEG DETAIL
BASE
2” (50.8MM) SCH 40
FEMALE THREADED
ADAPTER
ELEVATED SLAB MOUNTING USING FEET
EXTENDERS
2” (50.8MM) SCH 40
MALE THREADED
ADAPTER
Use additional 2” SCH 40 male threaded adapters which can be
threaded into the female threaded adapters to make additional
adjustments to the level of the unit.
FIGURE 4
IMPORTANT !
This model is designed for use in check / expansion
valve systems only. An indoor expansion valve ap
proved for use with HFC-410A refrigerant must be
ordered separately and installed prior to operating
the system.

Page 4
STEP 1 -- SETTING THE UNIT (Continued) -- Unit Placement
Unit Stabilizer Bracket Use
(field-provided):
Always use stabilizers when unit is
raised above the factory height.
(Elevated units could become unsta
ble in gusty wind conditions.)
Stabilizers may be used on any unit
installed on unstable and uneven
surfaces.
— Wind Barrier
DETAIL F
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 coil must be installed facing prevailing winter
winds, a wind barrier should be constructed. Size
barrier at least the same height and width as out
door unit. Install barrier 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
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 Mounting
#10 X 1/2” LONG SELF-DRILLING
SHEET METAL SCREWS
#10 X 1-1/4” LONG HEX HD SCREW
AND FLAT WASHER
STABILIZING UNIT ON UNEVEN SURFACES
DETAIL D !IMPORTANT !
MINIMUM ONE
PER SIDE
Stabilizing bracket (18 gauge metal — 2” [50.8mm] width; height as required); bend to form
right angle as shown below.
FOR EXTRA
STABILITY
— Deck Top Mounting
SAME FASTENERS AS
SLAB SIDE MOUNTING.
Install one bracket per side (minimum). For extra stability, install
two brackets per side, two inches (51mm) from each corner.
DETAIL E
FIGURE 5

Page 5
XP21 SERIES
STEP 2 -- ELECTRICAL -- Circuit Sizing and Wire Routing
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 cur
rent Canadian Electrical Code (CEC).
Refer to the furnace or air handler installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.
24VAC TRANSFORMER
Use the transformer provided with the furnace or air han
dler for low‐voltage control power (24VAC - 40 VA mini
mum)
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.
IMPORTANT !
If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start-up to pre
vent compressor damage as a result of slugging.
CAUTION
ELECTROSTATIC
DISCHARGE
(ESD)
Precautions and
Procedures
Electrostatic discharge can affect
electronic components. Take care
during unit installation and service to
protect the unit's electronic controls.
Precautions will help to avoid control
exposure to electrostatic discharge by
putting the unit, the control and the
technician at the same electrostatic
potential. Touch hand and all tools on an
unpainted unit surface before
performing any service procedure to
neutralize electrostatic charge.
1. Size Circuit and Install Disconnect: Refer to the unit
nameplate for minimum circuit ampacity, and maxi
mum fuse or circuit breaker size (HACR per NEC).
Install power wiring and properly sized disconnect
switch.
NOTE - Units are approved for use only with copper con
ductors. Ground unit at disconnect switch or connect to an
earth ground.
2. Install Thermostat: Install room thermostat (ordered
separately) on an inside wall in the center of the condi
tioned area and 5 feet (1.5m) from the floor. The ther
mostat should not be installed on an outside wall or
where it can be affected by sunlight or drafts.
NOTE - 24VAC, Class II circuit connections are made in
the control box.

Page 6
NOTE — For proper voltages, select control wires gauge per table below.
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 maintains
separation of field-installed low and high voltage circuits.
NOTE — Do not bundle any excess 24VAC control wires inside control box.
A. ROUTE CONTROL WIRES — NON-COMMUNICATING
CONTROL
(A175)
HOLE
Install low voltage control wiring from outdoor to indoor unit and from
thermostat to indoor unit. All low voltage wiring must enter unit through
provided field-installed busing installed in electrical inlet.
Run 24VAC control wires through hole with grommet.
Make 24VAC control wire connections to heat pump control (A175).
B. ROUTE CONTROL WIRES — COMMUNICATING
Maximum length of wiring (18 gauge) for all connections on the RSBus is 1500 feet (457 meters). Wires should be color-coded, with a temperature rating
of 95ºF (35ºC) minimum, and solid-core (Class II Rated Wiring). All low voltage wiring must enter unit through provided field-installed busing installed in
electrical inlet.
Communicatingsystems using the iComfort-enabled thermostat require four thermostat wires between the thermostat and the furnace/air handler con
trol and four wires between the outdoor unit and the furnace/air handler control. When a thermostat cable with more than four wires is used, the extra wires
must be properly connected to avoid electrical noise (see illustration below).
Use a wire nut to bundle the four unused wires at each end of the cable. Each bundle should also include an additional wire that should be connected
on each end to the C terminal as shown in the figure below.
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.
ROUTE HIGH VOLTAGE AND GROUND WIRES
CONTROL BOX
GROUND LUG*
CONTACTOR
WATERTIGHT
CONDUIT FITTING
WATERTIGHT
FLEXIBLE CONDUIT
TO SERVICE
DISCONNECT BOX
ACCESS VIEW
ELECTRICAL
INLET (HIGH
VOLTAGE)
WIRING ENTRY
POINTS
ELECTRICAL INLET (CONTROL WIRING —
LOW VOLTAGE). USE BUSHING
PROVIDED IN BAG ASSEMBLY HERE.
iComfort-enabled
thermostat
iComfort-enabled
Outdoor Unit
Single Wire To C
Terminal
Unused Wires
Unused Wires
* Attach field-provided
green ground wire to
provided ground lug.
NOTE - Grounding wire
must be a single, contin
uous wire run from unit
ground lug to earth
ground. DO NOT splice
wire.
A
B
Single Wire To C
Terminal
iComfort-enabled
Indoor Unit
FIGURE 6

Page 7
XP21 SERIES
STEP 2 -- ELECTRICAL (Continued) -- Outdoor Control (A175) Jumpers and Terminals
J1 - DEFROST TERMINATION TEMPERATURE
1. The J1 jumper is factory set to 50°F (10°C). This jumper can also be set to 70°F, 90°F, 100°For MAX
(21°C, 32°C, 38°C and MAX). If a jumper is not present on J1, the default termination temperature is MAX.
NOTE  Colder climates could require a higher defrost termination temperature setting to maintain a clear coil.
2. If the J1 jumper is set to MAX, defrost will run maximum defrost sequence.
J3 - DEFROST AUTO
1. Defrost Auto can be set to either ON or OFF.Factory default setting is OFF. Note: If the jumper is miss
ing the default is OFF.
2. Defrost Auto is set to OFF - Defrost will run and terminate based on J1 setting.
3. Defrost Auto is set to ON - Defrost termination setting may differ from the actual J1 jumper setting. The
actual defrost termination will be determined based on the following rules:
A..The first defrost after the unit is powered up, or the first defrost after cooling call will terminate based
on the J1 setting.
B..The control accumulates heating runtime between defrost cycles:
Heating time between defrost is less than 50 minutes - The defrost termination temperature
will be increased for the next defrost cycle based on current termination setting. If current ter
mination setting is <70°F then the next defrost termination will be 90°F. If J1 is set at >70°F or
MAX the next defrost termination will be MAX.
Heating time between defrosts is longer than 1 hour for 2 consecutive heating cycles
- The defrost termination will be decreased for the next defrost cycle. If the termination is set
at 50°F, 70°F, or 90°F, then defrost termination will follow the J1 jumper setting. If the J1 is set
to MAX, then the next defrost termination will be 90°F.
C..If J1 is set to MAX, the system will always run at MAX when accumulated compressor OFF time
is longer than 30 minutes and ambient temperature is less than 35°F.
D..When the ambient sensor temperature is higher than 40°F, and J1 is set to MAX, defrost termina
tion will be 90°F. If J1 is to 50°F, 70°F, 90°F or 100°F , defrost termination will follow the J1 setting.
55
50
DEGREE
TARGET
45
DEGREE
TARGET
40
DEGREE
TARGET (DEFAULT )
55
50
45
40
55
50
45
40
55
50
45
40
55
50
45
40
DEGREE
TARGET
100 90
DEGREE
TARGET
70
DEGREE
TARGET
50
DEGREE
TARGET
90F
70F
50F
TARGET
90F
70F
50F
90F
70F
50F
100F
90F
70F
50F
30
0
30
SECOND DELAY
SECOND DELAY
0
Cut for Humiditrol
®−Enhanced
Dehumification Accessory (EDA)
applications.
SECOND−STAGE LOCK−IN
TEMP
(HP ONLY) J4
J1 (HP ONLY)
J3 (HP ONLY)
DS TO R
(TWO−STAGE UNIT ONLY)
(TWO−STAGE HEAT
PUMP ONLY) J2
DEFROST TERMINATION TEMP
COMPRESSOR SHIFT DELAY
DEFROST AUTO
OFF
ON
JUMPER ON BOTH PINS
DEFROST AUTO ENABLED
DEFROST AUTO DISABLED (DEF AULT)
(DEFAULT)
90F
70F
50F
(DEFAULT)
ENABLED WHEN JUMPER IS
REMOVED OR MISSING)
NOTE −LINK NOT APPLICABLE TO
SINGLE−STAGE UNITS. CUTTING LINK WILL
HAVE NO AFFECT ON OPERATION OF
SINGLE−STAGE UNITS
.
100F
100F
100F
100F
JUMPER ON ONE PIN
RC
I+ I−Y1OY2WDS L
LPS HPS Y1
CNTCTR CY2 S REV Y2 CFPWM
Cut for option DS to R
H
I
G
H
V
O
L T
A
G
E
55F 50F 45F 40F
100F
90F 70F 50F
OPEN =OFF
OPEN
=90F
LOCK IN
2 STAGE
DEFROST
DFST AUTO
SHFT DLY
Assy # 105250UC
ECM ECM
CC
Liq. P Suct. P
Liq/Suct T
COIL AMB DIS
or
MAX TERM.
nd
F1
R81
R80
R75
R72
R69
R77
Q8
Q7
TVS8
R40
R140
R137
H1
H10
R34DNI2
S9
TVS3
R66
R128
R107
R58
Q9
D17
R59
R79
R39
TVS7
TVS4
TVS2
R37
R11
R103
U2
K2 K1
K5
K7
K4
F4
D45 R91
R90
R55
R54
R53
R52 R51
R50
R36
R147
C32
R146
L1
C30
C33
U6
R144
R130
R145
R143
D44 D43
H8
C29
C19
R63
U5
C28
R33
R99
R16
R120
R129
R123
R32
R124
R29
R8 R3
R133
R127
R9
R2
R134
R126
C9
C12
H5 H3
D39
D38
R64
R116
R115
R114
R113
R112R111
R110
R109
R96
R92
R5
R21
R19
R18
R13
R117
R97
R93
R73
R6
R22
R20
R14
R118
R78
R98
R95
R94
R7
R25
R23
R15
R119
R76
R88 R86
R83
R67
R30
C14
TP6
R60
R57 R48
R46 R44
R56
R47
R45 R31
Q4
Q15
Q14 Q13
Q12
D35
D2
D14 D11
D10
R142 R141
P6
P1
H15
C4 C17
U1
D52
C7
C5
C27
C26 C24 C23
C22
C21
C16
C15
C18
H2
D41
R132
D55
R89
D54
R87
D34
D53
H6
R85
D26
R26 R61
R38
C13
R68
H7
D23
R101
D37
F5 F3
C11
R74
TVS6
TVS5
D19
D13
R12
D27
D25
Q6
C25
D15
D24
R62
C1
C8
C20
C6
P23
P5
DSP1
P2
D36
D29
R43
P12
D9
R71 D42
D32
R70
D30
D33
H14
R139
P18 P17
R42
Q3
Q11
P3
U10
DNI1
R28
R27
P38 P7
R108
Q2
Q1 R41
R138
R65
R150
D47
H4
D31
C3
D7
D16
D6
D5
D12
D1
R35
C68
TVS1
R17
R10
H9
R24
D4 D8
R4
Q5
P16 P15
D3
R1
P4
Y2
SW1
C10
7−SEGMENT
DISPLAY
PUSH
BUTTON
DEGREE
(MAX DEFROST IS
SECOND−STAGE LOCK−IN FACTORY
DEFAULT SETTING FOR J2 IS 405F. IF
JUMPER IS REMOVED OR MISSING,
DEFAULT IS OFF.
FIGURE 7

Page 8
NOTE: Testing indicated
that the highest potential
for a weather event to
prevent fan operation due
to ice build up on the fan
blade and orifice ring is
when the outdoor ambient
is below 35ºF and the unit
is OFF for more than 30
minutes.
PREVIOUS TERMINATION
TEMPERATURE
TERMINATION TEMPERATURE
FOR NEXT DEFROST CYCLE
<70ºF OR UNKNOWN
≥70ºF, <90ºF
90ºF
MAX DEFROST MAX DEFROST
MAX DEFROST
MAX DEFROST
≥90ºF
FIGURE 8. Auto Defrost Rule

Page 9
XP21 SERIES
Fº
05 Fº07, º001roFº
09, F
Fº0
5Fº07, º0
01roFº09
,F
essirepm
uj1JfI t
°05ta ,
FFº07Fº09,
º001ro ,Ftsorfed
lliwnoit
animret
.g
nittes1Jeh
twollof
mumixaM−
ETON
rofdewo
llaemit
se
tunim41si
tsorfed .
See table on Page 10
Next defrost cycle should follow jumper setting. If MAX, use 90ºF.
100F
OFF = 90F OR MAX
FIGURE 9. Defrost Auto Selection and Max Defrost Sequence of Operation

Page 10
Termination temperature set on outdoor control is 50ºF,
70ºF, 90ºF or 100ºF. Coil temperature sensor input reached
the specified defrost termination temperature in less than
14 minutes.
Termination temperature set on
outdoor control is 50ºF, 70ºF, 90ºF
or 100ºF. Defrost for 14 minute
maximum without the coil
temperature sensor input reaching
termination temperature.
OFF = 90F
OR MAX
100F
FIGURE 10. Demand Defrost – MAX Defrost