INSTALLATION
E2012 Lennox Industries Inc.
Dallas, Texas, USA
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
WARNING
The State of California has determined that this product
may contain or produce a chemical or chemicals, in very
low doses, which may cause serious illness or death. It
may also cause cancer, birth defects, or reproductive
harm.
General
This XC21 outdoor unit is designed for use with HFC−410A
refrigerant only. This unit must be installed with an approved indoor unit. See the Lennox XC21 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.
INSTRUCTIONS
Dave Lennox Signature
Collection XC21 System
AIR CONDITIONERS
506923−01
7/2012
Supersedes 4/2012
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury or loss of life.
Installation and service must be performed by a licensed
professional installer (or equivalent) or service agency.
CAUTION
Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch.
NOTICE !
For more in−depth information, consult the Installation and Service Procedures manual, available as
Corp.1007−L2 on DaveNet or through the Technical
Support department at 800−453−6669.
®
Litho U.S.A.
STEP 1 −− SETTING THE UNIT −− Clearances
CLEARANCE ON ALL SIDES INCHES (MILLIMETERS)
6 (152)
CONTROL
PANEL ACCESS
LOCATION
24
(610)
30 (762)
12 (305)
36 (914)
MINIMUM CLEARANCE BETWEEN TWO UNITS
NOTES:
S Clearance to access panel must be 30
inches (762mm).
S Clearance to one of the other three
sides must be 36 inches (914mm).
S Clearance to one of the remaining two
sides may be 12 inches (305mm) and
the final side may be 6 inches
(152mm).
ACCESS PANEL
LINE SET
CONNECTIONS
MINIMUM CLEARANCE
ABOVE UNIT
48 (1219)
REAR VIEW OF UNIT
FIGURE 1
7/2012 506923−01
Page 1
*2P72012* *P506923-01*
UNIT DIMENSIONS − INCHES (MM)
39−1/2
(1003)
DISCHARGE
AIR
SUCTIOn
LINE
INLET
LIQUID
LINE
INLET
ELECTRICAL
INLETS
47
(1194)
18−1/2
(470)
35−1/2
(902)
4−1/2
(114)
8 (203)
SIDE VIEW
UNIT SUPPORT
FEET
16−7/8
(429)
8−3/4
(222)
3−1/8
(79)
BASE WITH ELONGATED LEGS
STEP 1 −− SETTING THE UNIT (Continued)
−− Unit Placement
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.
30−3/4
(781)
1 (25)
26−7/8
(683)
3−3/4 (95)
4−5/8
(117)
ACCESS VIEW
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.
Page 2
PLACEMENT
INSTALL UNIT AWAY
FROM WINDOWS
STABILIZING UNIT ON UNEVEN SURFACES
#10 X 1/2" LONG
SELF−DRILLING
SHEET METAL
SCREWS
COIL
TWO 90_ ELBOWS INSTALLED IN LINE SET
WILL REDUCE LINE SET VIBRATION
FIGURE 2
SLAB MOUNTING
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.
BUILDING
STRUCTURE
DISCHARGE AIR
MOUNTING
SLAB
GROUND LEVEL
FIGURE 3
ELEVATED SLAB MOUNTING USING FEET
EXTENDERS
2" (50.8MM) SCH 40
FEMALE THREADED
ADAPTER
2" (50.8MM)
SCH 40 MALE
THREADED
ADAPTER
LEG DETAIL
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.
BASE
STABILIZING BRACKET
(18 GAUGE METAL 2"
WIDTH; HEIGHT AS
REQUIRED)
#10 X 1−1/4" LONG
HEX HD SCREW AND
FLAT WASHER
Concrete slab use two
plastic anchors (hole drill 1/4")
!
IMPORTANT !
CORNER POST
BASE PAN
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 any unit installed
on unstable and uneven surfaces.
FIGURE 5
STEP 2 −− REFRIGERANT PIPING −− Flushing Existing Line Set & Indoor Coil
Flush the existing line set per the following instruc-
tions. For more information, refer to the Installation
and Service Procedures manual available on DaveNet. CAUTION − DO NOT attempt to flush and re−use ex-
isting line sets or indoor coil when the system contains contaminants (i.e., compressor burn out).
NOTE − When installing refrigerant lines longer than 50
feet, refer to the Refrigerant Piping Design and Fabrication
Guidelines manual available on DaveNet (Corp. 9351−L9),
or contact the Technical Support Department Product Application group for assistance.
NOTE − For new or replacement line set installation, refer
to Service and Application Note − Corp. 9112−L4 (C−91−4).
TABLE 1
REFRIGERANT LINE SET INCHES (MM)
Models Liquid
Line
−024, −036
and−048
3/8 (10) 7/8 (22) L15 line set sizes are
Vapor/
Suction
Line
L15 Line Set
dependent on unit match up.
See XP21 Engineering
Handbook to determine
correct line set sizes.
FIGURE 4
−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.
Page 3
XC21 SERIES
IMPORTANT !
If this unit is being matched with an approved line
set or indoor unit coil that 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 system performance and capacity.
Failure to properly flush the system per this instruction and the detailed Installation and Service Procedures manual will void the warranty.
WARNING
When using a high pressure gas such as
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
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 explosion, that could result in
property damage, personal injury or death.
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.
IMPORTANT !
Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction pressure goes below 20 psig. A hissing sound will be
heard when the compressor is running unloaded.
Protector will reset when low pressure in system is
raised above 40 psig. DO NOT REPLACE COMPRESSOR.
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.
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment.
Page 4
STEP 2 −− REFRIGERANT PIPING −− Removing Existing Indoor Metering Device
TYPICAL EXISTING FIXED ORIFICE
1A
DISTRIBUTOR
ASSEMBLY
1. On fully cased coils, remove the coil access and plumbing panels.
2. Remove any shipping clamps from the liquid line and distributor as-
sembly.
3. Using two wrenches, disconnect liquid line from liquid line orifice hous-
ing. 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 temporarily reconnect the liquid line to the
indoor unit’s liquid line orifice housing.
(UNCASED COIL SHOWN)
DISTRIBUTOR TUBES
LIQUID LINE ORIFICE HOUSING
TEFLON® RING
FIXED ORIFICE
REMOVE AND DISCARD
WHITE TEFLON
(IF PRESENT)
®
SEAL
LIQUID LINE ASSEMBLY
(INCLUDES STRAINER)
REMOVAL PROCEDURE
OR
BRASS NUT
1B
TWO−PIECE PATCH PLATE
CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE
2
CYLINDER CONTAINING
CLEAN HCFC−22 TO BE
USED FOR FLUSHING
(Positioned to deliver liquid
A
refrigerant)
1
VAPOR LINE
SERVICE VALVE
EXISTING
INDOOR
UNIT
LIQUID LINE SERVICE
VALV E
RECOVERY
CYLINDER
VAPOR
LIQUID
OUTDOOR
B
NEW
UNIT
OPENED
C
D
RECOVERY MACHINE
1. HCFC−22 cylinder with clean refrigerant (positioned to deliver liquid
refrigerant) to the vapor 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 connected to the gauge set.
4. Connect recovery tank to recovery machine per machine instructions.
GAUGE
MANIFOLD
LOW HIGH
CLOSED
TANK
RETURN
INLET
DISCHARGE
TYPICAL EXISTING EXPANSION VALVE REMOVAL
PROCEDURE (UNCASED COIL SHOWN)
ORIFICE
HOUSING
EQUALIZER
LINE
STUB END
TEFLON
RING
VAPOR
EXPANSION
VALV E
®
LIQUID LINE
ASSEMBLY WITH
BRASS NUT
LINE
TEFLON
RING
®
SENSING
(UNCASED COIL ONLY)
DISTRIBUTOR
TUBES
DISTRIBUTOR
ASSEMBLY
MALE EQUALIZER
LINE FITTING
1. On fully cased coils, remove the coil access and plumbing panels.
2. Remove any shipping clamps from the liquid line and distributor
assembly.
3. Disconnect the equalizer line from the check expansion valve
equalizer line fitting on the vapor line.
4. Remove the vapor line sensing bulb.
5. Disconnect the liquid line from the check expansion valve at the liquid
line assembly.
6. Disconnect the check expansion valve from the liquid line orifice
housing. Take care not to twist or damage distributor tubes during this
process.
7. Remove and discard check expansion valve and the two Teflon® rings.
8. Use a field−provided fitting to temporarily reconnect the liquid line to the
indoor unit’s liquid line orifice housing.
LIQUID LINE
SENSING BULB
FLUSHING LINE SET
The line set and indoor unit coil must be flushed with at least the same
3
amount of clean refrigerant that previously charged the system. Check
the charge in the flushing cylinder before proceeding.
1. Set the recovery machine for liquid recovery and start the recovery
machine. 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. Position the cylinder of clean HCFC−22 for delivery of liquid refrigerant
3. After all of the liquid refrigerant has been recovered, switch the
4. Close the valve on the inverted HCFC−22 drum and the gauge set
B
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.
recovery machine to vapor recovery so that all of the HCFC−22 vapor
is recovered. Allow the recovery machine to pull the system down to 0.
valves. Pump the remaining refrigerant out of the recovery machine
and turn the machine off.
LINE
LIQUID
LINE
FIGURE 6
Page 5
XC21 SERIES
STEP 2 −− REFRIGERANT PIPING −− Brazing Procedures
PIPING PANEL REMOVAL / PREPARING LINE SET
Remove piping panel to access service valves. Cut
1
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.
CUT AND DEBUR
LINE SET SIZE MATCHES
SERVICE VALVE CONNECTION
SERVICE VALVE
COPPER TUBE
REDUCER
CONNECTION
STUB
REFRIGERANT LINE
LINE SET SIZE IS SMALLER
THAN CONNECTION
CAP AND CORE REMOVAL
Remove service cap and core from both the suction /
2
vapor and liquid line service ports.
SERVICE PORT CAP
SERVICE PORT
CORE
LIQUID LINE SERVICE VALVE
SERVICE PORT
CORE
SERVICE
PORT CAP
SUCTION / VAPOR LINE
DO NOT CRIMP SERVICE VALVE
CONNECTOR WHEN PIPE IS
SMALLER THAN CONNECTION
SERVICE VALVE
ATTACH THE MANIFOLD GAUGE SET FOR BRAZING
LIQUID AND SUCTION / VAPOR LINE SERVICE VALVES
3
A. Connect gauge set low pressure side to liquid line service valve (service port).
B. Connect gauge set center port to bottle of nitrogen with regulator.
C. With valve core removed from the suction / vapor line service port, nitrogen flow will have an exit point.
HIGHLOW
ATTACH
GAUGES
SUCTION / VAPOR SERVICE PORT MUST BE
OPEN AND SERVICE PORT CORE REMOVED
TO ALLOW EXIT POINT FOR NITROGEN FLOW
SUCTION / VAPOR
LINE
INDOOR
UNIT
LIQUID LINE
C
LIQUID LINE SERVICE
SUCTION /
VAPOR LINE
SERVICE
VALV E
VALV E
A
B
OUTDOOR
UNIT
NITROGEN
FIGURE 7
Page 6
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.
WRAP SERVICE VALVES
To help protect service valve seals during brazing, wrap water−saturated cloths around service valve bodies and copper tube stubs. Use
4
additional water−saturated cloths under the valve body to protect the base paint.
FLOW NITROGEN
Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration
5
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.
BRAZE LINE SET
Cloths must remain water−saturated throughout the brazing and
6
cool−down process.
1. Braze liquid line to liquid line service valve.
2. Braze suction / vapor line to suction / vapor service
valve.
FIRE, PERSONAL INJURY, OR PROPERTY DAMAGE
may 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 the line set! The braze, when
complete, must be quenched with water to absorb any
residual heat.
Do not open service valves until refrigerant lines and
indoor coil have been leak−tested and evacuated. Refer
to Installation and Service Procedures manual found on
DAVENET.
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
SUCTION / VAPOR LINE
WATER−SATURATED CLOTHS
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.
LIQUID LINE
6B
6A
WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.
SUCTION / VAPOR SERVICE
PORT MUST BE OPEN AND
SERVICE PORT CORE RE-
MOVED TO ALLOW EXIT POINT
FOR NITROGEN FLOW
WATER−SATURATED
PREPARATION FOR NEXT STEP
After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water−saturated cloths to both
7
services valves to cool piping. Once piping is cool, remove all water−saturated cloths.
FIGURE 8
Page 7
CLOTHS
XC21 SERIES
STEP 3 −− INSTALLING INDOOR EXPANSION VALVE
This outdoor unit is designed for use in systems that include an expansion valve metering device. See the XC21 Product
Specifications bulletin (EHB) for approved expansion valve kit match−ups and application information. The expansion valve
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 expansion valve in a manner that will provide access for future field service of the expansion valve.
Refer to below illustration for reference during installation of expansion valve.
INDOOR EXPANSION VALVE INSTALLATION
TWO−PIECE
PATCH PLATE
(UNCASED
COIL ONLY)
DISTRIBUTOR
TUBES
DISTRIBUTOR
ASSEMBLY
MALE EQUALIZER LINE
FITTING (SEE
EQUALIZER LINE
INSTALLATION FOR
DETAILS)
(Uncased Coil Shown)
LIQUID LINE
ORIFICE
HOUSING
STUB
END
TEFLON
RING
EQUALIZER
LINE
VAPOR
EXPANSION
VALV E
®
ASSEMBLY WITH
LINE
TEFLON
LIQUID LINE
BRASS NUT
RING
®
SENSING
LINE
Sensing bulb insulation is required if
expansion valve is installed external to the
coil casing. See sensing bulb installation for
LIQUID LINE
bulb positioning.
EQUALIZER LINE INSTALLATION
1. Remove 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 illustrated in the figure below.
2. Remove the field−provided fitting that temporarily reconnected
the liquid line to the indoor unit’s distributor assembly.
3. Install one of the provided Teflon® rings around the
stubbed end of the expansion valve and use refrigerant
oil to lightly lubricate the connector threads and exposed surface of the Teflon® ring.
4. Attach the stubbed end of the expansion valve to the
liquid line orifice housing. Finger tighten, then use an
appropriately sized wrench to turn an additional 1/2
turn clockwise as illustrated in the figure to the right, or
tighten to 20 ft−lb.
5. Place the remaining Teflon® washer around the other
end of the expansion valve. Lightly lubricate connector
threads and expose surface of the Teflon® ring with
refrigerant oil.
6. Attach the liquid line assembly to the expansion valve.
Finger tighten, then use an appropriately sized wrench
to turn an additional 1/2 turn clockwise as illustrated in
the figure above or tighten to 20 ft−lb.
SENSING BULB INSTALLATION
1. Attach the vapor line sensing bulb in the proper orienta-
tion as illustrated below using the clamp and screws
provided.
2. NOTE − Though it is preferred to have the sensing bulb
installed on a horizontal run of the vapor line, installation
on a vertical run of piping is acceptable if necessary.
NOTE Confirm proper thermal contact between vapor line
and expansion bulb before insulating the sensing bulb.
3. Connect the equalizer line from the expansion valve to
the equalizer vapor port on the vapor line. Finger tighten
the flare nut, then tighten an additional 1/8 turn (7 ft−lbs)
as illustrated to the right.
VAPOR LINE
BULB
12
ON LINES SMALLER THAN
7/8", MOUNT SENSING
BULB AT EITHER THE 3 OR
9 O’CLOCK POSITION.
BULB
1/2 Turn
11
10
9
8
7
1/8 Turn
11
10
9
8
7
12
1
2
3
4
5
6
12
1
2
3
4
5
6
FLARE SEAL CAP
OR
FLARE NUT
COPPER FLARE
SEAL BONNET
MALE BRASS EQUALIZER
LINE FITTING
VAPOR LINE
FIGURE 9
Page 8
VAPOR LINE
12
BULB
NOTE NEVER MOUNT THE SENSING
BULB ON BOTTOM OF LINE.
ON 7/8" AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O’CLOCK
POSITION. NEVER MOUNT
THE SENSING BULB ON
BOTTOM OF LINE.
BULB
STEP 4 −− LEAK TEST AND EVACUATION
HIGHLOW
MANIFOLD GAUGE SET
OUTDOOR UNIT
B
TO VAPOR
SERVICE VALVE
NOTE − Position
canister to deliver
liquid refrigerant.
NITROGEN
CONNECT GAUGE SET
A. Connect the high pressure hose of an HFC−410A manifold gauge set to the vapor valve service port.
1
2
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.
B. 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 replaced by the nitrogen container.
TEST FOR LEAKS
After the line set has been connected to the indoor and outdoor units, check the line set connections
and indoor unit for leaks. Use the following procedure to test for leaks:
A. 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 (vapor only).
B. 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) refriger-
ant 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.
C. Connect a cylinder of nitrogen with a pressure regulating valve to the center port of the manifold
gauge set.
D. Adjust 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.
E. 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.
F. After leak testing, disconnect gauges from service ports.
HFC−410A
A
FIGURE 10
Page 9
XC21 SERIES
STEP 4 −− LEAK TEST AND EVACUATION (Continued)
EVACUATION
CONNECT GAUGE SET
NOTE Remove cores from service valves (if not already done).
3
A. Connect low side of manifold gauge set with
1/4 SAE in−line tee to vapor line service valve
B. Connect high side of manifold gauge set to
liquid line service valve
C. Connect available micron gauge connector
on the 1/4 SAE in−line tee.
D. Connect 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.
NITROGEN
NOTE − Position
canister to deliver
liquid refrigerant.
HFC−410A
VACUUM PUMP
OUTDOOR
UNIT
A
B
1/4 SAE TEE WITH SWIVEL
COUPLER
500
C
MICRON
GAUGE
GAUGE SET
TO VAPOR
SERVICE VALVE
TO LIQUID LINE
SERVICE VALVE
LOW
MANIFOLD
D
EVACUATE THE SYSTEM
4
A. Open both manifold valves and start the vacuum pump.
B. 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 above zero within a given volume or system. Absolute pressure in a
vacuum is equal to atmospheric pressure minus vacuum pressure.
C. When the absolute pressure reaches 23,000 microns (29.01 inches of mercury),
perform the following:
S Close manifold gauge valves.
S Close valve on vacuum pump.
S Turn off vacuum pump.
S Disconnect manifold gauge center port hose from vacuum pump.
S Attach manifold center port hose to a nitrogen cylinder with pressure
regulator set to 150 psig (1034 kPa) and purge the hose.
S Open manifold gauge valves to break the vacuum in the line set and indoor
unit.
S Close manifold gauge valves.
D. Shut off the nitrogen cylinder and remove the manifold gauge hose from the cylinder. Open the manifold gauge valves to release the nitrogen
from the line set and indoor unit.
E. 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.
F. When the absolute pressure requirement above has been met, disconnect the manifold hose from the vacuum pump and connect it to a
cylinder of HFC−410A positioned to deliver liquid refrigerant. Open the manifold gauge valve 1 to 2 psig in order to release the vacuum in the line
set and indoor unit.
G. Perform the following:
S Close manifold gauge valves.
S Shut off HFC−410A cylinder.
S Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core
tool while maintaining a positive system pressure.
S Replace stem caps and finger tighten them, then tighten an additional one−sixth (1/6) of a turn as illustrated.
Possible equipment damage.
Avoid deep vacuum operation. Do not use
compressors to evacuate a system.
Extremely low vacuum can cause internal
arcing and compressor failure. Damage
caused by deep vacuum operation will
void warranty.
WARNING !
RECOMMEND
MINIMUM 3/8" HOSE
1/6 TURN
12
11
10
9
8
7
HIGH
1
2
3
4
5
6
FIGURE 11
Page 10
STEP 5 −− 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 current
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 handler for low-voltage control power (24VAC − 40 VA minimum)
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.
If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start−up to prevent compressor damage as a result of slugging.
ELECTROSTATIC
DISCHARGE
(ESD)
Precautions and
Procedures
IMPORTANT !
CAUTION
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.
SIZE CIRCUIT AND INSTALL DISCONNECT
SWITCH
1
Refer to the unit nameplate for minimum circuit
ampacity, and maximum fuse or circuit breaker size
(HACR per NEC). Install power wiring and properly
sized disconnect switch.
SERVICE
DISCONNECT
SWITCH
NOTE Units are approved for use only with copper
conductors. Ground unit at disconnect switch or
connect to an earth ground.
FIGURE 12
INSTALL THERMOSTAT
Install room thermostat (ordered separately) on an
2
inside wall in the center of the conditioned area and
5 feet (1.5m) from the floor. The thermostat should
not be installed on an outside wall or where it can be
affected by sunlight or drafts.
THERMOSTAT
5 FEET
(1.5M)
NOTE 24VAC, Class II circuit connections are made
in the control box.
Page 11
XC21 SERIES
A. ROUTE CONTROL WIRES NON−COMMUNICATING
3
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 outdoor control (A175).
NOTE Do not bundle any excess 24VAC control wires inside control box.
NOTE Wire tie provides low voltage wire strain relief and maintains
separation of field−installed low and high voltage circuits.
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.
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.
Communicating systems using the icomfortt−enabled thermostat require four thermostat wires between the thermostat and the furnace/air handler control 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.
icomfortt−enabled
Outdoor Unit
icomfortt−enabled
Indoor Unit
B
A
HOLE
CONTROL
(A175)
Single Wire To C
Terminal
Unused Wires
Single Wire To C
Terminal
Unused Wires
ROUTE HIGH VOLTAGE AND GROUND WIRES
Any excess high voltage field wiring should be trimmed and secured away from any low voltage field wiring. To facilitate a conduit, a
4
cutout is located in the bottom of the control box. Connect conduit to the control box using a proper conduit fitting.
WATERTIGHT
CONDUIT FITTING
WATERTIGHT FLEX-
IBLE CONDUIT
TO SERVICE
DISCONNECT BOX
GROUND LUG*
CONTACTOR
ELECTRICAL INLET (CONTROL WIRING
LOW VOLTAGE). USE BUSHING
PROVIDED IN BAG ASSEMBLY HERE.
CONTROL BOX
ELECTRICAL
INLET (HIGH
VOLTAGE)
WIRING ENTRY
POINTS
ACCESS VIEW
icomfortt−enabled
thermostat
* Attach field−provided
green ground wire to
provided ground lug.
NOTE − Grounding wire
must be a single, continuous wire run from unit
ground lug to earth
ground. DO NOT splice
wire.
FIGURE 13
Page 12
STEP 5 −− ELECTRICAL (Continued) −− Outdoor Control (A175) Jumpers and Terminals
Communication System
The jumper settings and link are default settings and ONLY control
system operation if configuration settings in the icomfortt−enabled
thermostat are not available.
Non−Communicating System
The unit will operate based on jumper settings and R−TO− DS link on
the MAIN CONTROL. All unit setting changes must be done at the
MAIN CONTROL. The Lennox ComfortSense 7000 thermostat
may be used, as well as other non−communicating electronic−only
thermostats.
7−SEGMENT
DISPLAY
Set up of jumpers on
replacement outdoor
control.
PUSH
BUTTON
(HP ONLY) J4
COMPRESSOR SHIFT DELAY
30
SECOND DELAY
(DEFAULT)
0
SECOND DELAY
30
0
(TWO−STAGE HEAT
PUMP ONLY) J2
SECOND−STAGE LOCK−IN
TEMPERATURE
55
DEGREE
TARGET
50
DEGREE
TARGET
45
DEGREE
TARGET
55
50
45
40
55
50
45
40
55
50
45
40
The Lennox icomfortt−enabled thermostat must be
used in communicating applications.
NOTE Fan cycling routine when activated will cycle the
fan ON for five minutes if the outdoor ambient air
temperature is between 15ºF and 35ºF and the
compressor has been OFF for 25 to 30 minutes. This
option is to help reduce the potential for ice build up on the
orifice ring during system OFF cycles that are greater
than 25 to 30 minutes.
J3 ALL UNITS)
FAN CYCLING
SEE NOTE ABOVE FOR FURTHER DETAILS.
JUMPER ON
FAN ON FOR 5 MINUTES
JUMPER OFF
DISABLE (DEFAULT)
ON
OFF
J1 (HP ONLY)
DEFROST TERMINATION TEMPERATURE
100
DEGREE
TARGET
100
90
70
50
100
90
90
70
50
90
DEGREE
TARGET
70
DEGREE
TARGET
50
DEGREE
TARGET
(DEFAULT)
100
90
70
50
(DEFAULT WHEN JUMPER IS
REMOVED OR MISSING)
100
90
70
50
100
90
70
50
DS TO R TWO−STAGE UNIT
ONLY)
Cut for Humiditrol® − Enhanced
Dehumification Accessory (EDA)
applications.
NOTE − LINK NOT APPLICABLE TO
ONE−STAGE UNITS. CUTTING LINK WILL
HAVE NO AFFECT ON OPERATION OF
ONE−STAGE UNITS
.
40
DEGREE
TARGET (DEFAULT)
55
50
45
40
FIGURE 14
Page 13
XC21 SERIES
STEP 5 −− ELECTRICAL (Continued) −− Field Control Wiring
The following two illustrations provide examples of control wiring connections when using a non−communicating thermostat.
For examples of control wiring in complete or partial communicating systems, see the icomfortt−enabled thermostat Quick
Start Guide which is provided with the thermostat.
Air Handler
ComfortSense[ 7000 Thermostats
Catalog # Y0349 or Y2081
R
G
W2
W1
O
L
H
On−board link
Low voltage thermostat
wiring
Flat metal jumper
XC21 Two−Stage
Air Conditioner Control
W
L
Y2
Y1
O
DS
7
DS
O
L
H
DH
R
2
6
1. Thermostat T terminals are used for outdoor sensor input. Use for thermostat’s outdoor temperature display (optional).
2. R to L connection is required for this model when using the ComfortSense
required and ordered separately.
3. Air handler control ships from factory with metal jumpers installed across W1, W2 and W3. For one−stage electric heat, do not remove factory
installed metal jumpers.
4. Air handler control ships from factory with metal jumpers installed across W1, W2 and W3. For two−stage electric heat, remove factory installed metal
jumper between W1 to W2. Then connect thermostat wire between the air handler control’s W2 and the thermostat’s W2 terminal.
5. Cut on−board link (clippable wire) from Y1−Y2 2 STAGE COMPR for two−stage compressor and two−speed fan operation.
6. Cut loop jumper (clippable wire) DS to R on two−stage units for Humiditrol® applications. This will slow the outdoor unit’s fan speed to a specific
RPM. A wire must be installed between the DS terminals on the air handler and outdoor unit controls.
7. Cut on−board link (clippable wire) DS−R for Humiditrol
setting. See air handler installation instruction or engineering handbook for lowest fan speed information.
C
R
3
C
Y1
5
Y2
G
W3
W2
4
W1
®
7000 − catalog number Y0349 only. Resistor Kit (catalog number 47W97)
®
or Harmony IIIt applications. This will slow the indoor blower motor to the lowest speed
D
B
Y2
1
Y1
C
T
T
FIGURE 15
Page 14
XC21 Two−Stage Air
Conditioner Control
W
L
Y2
Y1
O
DS
5
Furnace
DS
O
L
H
DH
R
ComfortSense[ 7000 Thermostats
Catalog # Y0349 or Y2081
R
G
W2
W1
O
L
H
On−board link
Low voltage thermostat
wiring
2
4
C
R
C
Y1
3
Y2
G
D
B
Y2
1
Y1
C
W2
T
W1
T
1. Thermostat T terminals are used for outdoor sensor input. Use for thermostat’s outdoor temperature display (optional).
2. R to L connection is required for this model when using the ComfortSense
47W97) required and ordered separately.
3. Cut on−board link W915 (clippable wire) for two−stage operation.
4. Cut loop jumper (clippable wire) DS to R on two−stage units for Humiditrol® applications. This will slow the outdoor unit’s fan speed to a specific
RPM. A wire must be installed between the DS terminals on the furnace and outdoor unit controls.
5. Cut on−board link (clippable wire) DS−R for Humiditrol
setting. See furnace installation instruction or engineering handbook for lowest fan speed information.
®
or Harmony IIIt applications. This will slow the indoor blower motor to the lowest speed
®
7000 − catalog number Y0349 only. Resistor Kit (catalog number
FIGURE 16
Page 15
XC21 SERIES
Charging
The XC21 unit is factory−charged with enough HFC−410A
refrigerant to accommodate a 15−foot length of refrigerant
piping. Charge should be checked and adjusted using the
tables provided on the charging procedure sticker on the
unit access panel. Detailed information is given in the
XC21 Installation and Service Procedures manual, which
is available on DaveNet.
Start−Up Checklists
TWO−STAGE COMPRESSOR PERFORMANCE
Use this procedure to verify part- and full-load capacity operation of the two-stage compressor.
IMPORTANT !
This performance check is ONLY valid on systems that
have clean indoor and outdoor coils, proper airflow over
coils, and correct system refrigerant charge. All
components in the system must be functioning properly
to correctly perform compressor operational check.
(Accurate measurements are critical to this test as
indoor system loading and outdoor ambient can affect
variations between low and high capacity readings).
TOOLS REQUIRED
S Refrigeration gauge set
S Digital volt/amp meter
S Electronic temperature thermometer
S On-off toggle switch
PROCEDURE
1. Turn main power OFF to outdoor unit.
2. Adjust room thermostat set point 5ºF above (heating
operation) or 5ºF below (cooling operation) the room
temperature.
3. Remove control access panel. Install refrigeration
gauges on unit. Attach the amp meter to the common
(black wire) wire of the compressor harness. Attach
thermometer to discharge line as close as possible to
the compressor.
4. Turn toggle switch OFF. Install switch in series with Y2
wire from room thermostat. (See note ** in the Field
Operational Checklist on page 17).
5. Cycle main power ON.
6. Allow pressures and temperatures to stabilize before
taking any reading (may take up to 10 minutes).
7. Record all of the readings for the Y1 demand.
8. Close switch to energize Y2 demand. Verify power is
going to compressor solenoid (see note ** in the Field
Operational Checklist on page 17).
9. Allow pressures and temperatures to stabilize before
taking any reading (may take up to 10 minutes).
10. Record all of the readings with the Y1 and Y2 demand.
11. If temperatures and pressures change in the direction
noted in chart, the compressor is properly modulating
from low to high capacity. (If no amperage, pressures
or temperature readings change when this test is performed, the compressor is not switching between low
and high capacity and replacement is necessary.)
12. After testing is complete, return unit to original set up.
Page 16
XC21 Field Operational Checklist
Cooling*** Heating***
Unit Readings
Compressor
Voltage Same Same
Amperage Higher Higher
Condenser Fan motor
Amperage Same or Higher Same or Higher
Temperature
Ambient Same Same
Outdoor Coil Discharge Air Higher Lower
Compressor Discharge Line Higher Higher
Indoor Return Air Same Same
Indoor Coil Discharge Air Lower Higher
Pressures
Y1
First
Stage
Expected results
during Y2 demand
(toggle switch ON)
Y2
Second
Stage
Y1
First Stage
Expected results
during Y2 demand
(toggle switch ON)
Y2 Second
Stage
Suction (Vapor) Lower Down
Liquid Higher Higher
Note − Unit may have a low ambient control or control that locks in second−stage operation below its set point. It may be necessary to remove a wire
from the control when performing this check.
** On the XC21 units, the System Operation Monitor controls the second−stage solenoid coil in compressor.
*** Cooling Mode Operation − Block outdoor coil to maintain a minimum of 375 psig during testing.
Page 17
XC21 SERIES
XC21 Start−Up and Performance Checklist
Customer Address
Indoor Unit Model Serial
Outdoor Unit Model Serial
Solar Module Mfg and Model Serial
Notes:
START−UP CHECKS
Refrigerant Type:
Rated Load Amps Actual Amps Rated Volts Actual Volts
Condenser Fan Full Load Amps Actual Amps:
COOLING MODE
Vapor Pressure: Liquid Pressure:
Supply Air Temperature: Ambient Temperature: Return Air Temperature:
HEATING MODE
Vapor Pressure: Liquid Pressure:
Supply Air Temperature: Ambient Temperature: Return Air Temperature:
System Refrigerant Charge (Refer to manufacturer’s information on unit or installation instructions for required
subcooling and approach temperatures.)
Subcooling:
Saturated Condensing Temperature (A)
minus Liquid Line Temperature (B)
Approach:
Liquid Line Temperature (A)
minus Outdoor Air Temperature (B)
Indoor Coil Temp. Drop (18 to 22°F)
Return Air Temperature (A)
minus Supply Air Temperature (B)
A B = SUBCOOLING
A B = APPROACH
A B = COIL TEMP DROP
Page 18
Homeowner Information
CAUTION
Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch.
Cleaning of the outdoor unit’s coil should be performed by
a licensed professional service technician (or equivalent).
Contact your dealer and set up a schedule (preferably
twice a year, but at least once a year) to inspect and service your outdoor unit. The following maintenance may be
performed by the homeowner.
IMPORTANT !
Sprinklers and soaker hoses should not be installed
where they could cause prolonged exposure to the
outdoor unit by treated water. Prolonged exposure
of the unit to treated water (i.e., sprinkler systems,
soakers, waste water, etc.) will corrode the surface
of steel and aluminum parts, diminish performance
and affect longevity of the unit.
Outdoor Coil
The outdoor unit must be properly maintained to ensure its
proper operation.
S Please contact your dealer to schedule proper inspec-
tion and maintenance for your equipment.
S Make sure no obstructions restrict airflow to the outdoor
unit.
S Grass clippings, leaves, or shrubs crowding the unit can
cause the unit to work harder and use more energy.
S Keep shrubbery trimmed away from the unit and periodi-
cally check for debris which collects around the unit.
S Keep snow level below the louvered panels to ensure
proper performance.
Routine Maintenance
In order to ensure peak performance, your system must be
properly maintained. Clogged filters and blocked airflow
prevent your unit from operating at its most efficient level.
NOTE The filter and all access panels must be in place
any time the unit is in operation. If you are unsure about the
filter required for your system, call your Lennox dealer for
assistance.
1. Ask your Lennox dealer to show you where your indoor
unit’s filter is located. It will be either at the indoor unit
(installed internal or external to the cabinet) or behind
a return air grille in the wall or ceiling. Check the filter
monthly and clean or replace it as needed.
2. Disposable filters should be replaced with a filter of the
same type and size.
3. The indoor evaporator coil is equipped with a drain pan
to collect condensate formed as your system removes
humidity from the inside air. Have your dealer show
you the location of the drain line and how to check for
obstructions. (This would also apply to an auxiliary
drain, if installed.)
Thermostat Operation
See the ComfortSense® 7000 or icomfortt−enabled thermostat homeowner manual for instructions on how to operate your thermostat.
Preservice Check
If your system fails to operate, check the following before
calling for service:
S Verify room thermostat settings are correct.
S Verify that all electrical disconnect switches are ON.
S Check for any blown fuses or tripped circuit breakers.
S Verify unit access panels are in place.
S Verify air filter is clean.
S If service is needed, locate and write down the unit
model number and have it handy before calling.
Page 19
XC21 SERIES
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