Lenox Air Conditioner Elite Series Xp16 Units Heat Pumps Users Manual 506640a

Lenox Air Conditioner Elite Series XP16 Units Heat Pumps Lennox_XP16_IOM

Elite Series XP16 Units Heat Pumps to the manual 4a0ca56a-af7f-4082-a8f4-4c8427d7732c

2015-02-09

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INSTALLATION
INSTRUCTIONS

E20 Lennox Industries Inc.
Dallas, Texas, USA

Elite® Series XP16 Units
HEAT PUMPS
These instructions are intended as a
general guide and do not supersede
local codes in any way. Consult
authorities having jurisdiction before
installation.

RETAIN THESE INSTRUCTIONS FOR FUTURE
REFERENCE

NOTICE TO INSTALLER
BRAZING LINE SET TO SERVICE VALVES
It is imperative to follow the brazing technique illustrated starting on
page 11 to avoid damaging the service valve’s internal seals.

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, HFCs, and HCFCs) as of July 1,
1992. Approved methods of recovery, recycling or
reclaiming must be followed. Fines and/or incarceration
may be levied for noncompliance.

506640−01
12/10
Supersedes 11/10

TABLE OF CONTENTS
Shipping and Packing List . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model Number Identification . . . . . . . . . . . . . . . . . . . .
Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Parts Arrangement . . . . . . . . . . . . . . . . . . . . . .
Caps and Fasteners Torque Requirements . . . . . . . .
Operating Gauge Set and Service Valves . . . . . . . . .
Recovering Refrigerant from Existing System . . . . .
New Outdoor Unit Placement . . . . . . . . . . . . . . . . . . .
Removing and Installing Panels . . . . . . . . . . . . . . . . .
Line Set Requirements . . . . . . . . . . . . . . . . . . . . . . . . .
Brazing Connections . . . . . . . . . . . . . . . . . . . . . . . . . . .
Indoor Refrigerant Metering Device Removal and
Flushing Line Set and Indoor Coil . . . . . . . . . . . . . . . .
Installing New Indoor Metering Device . . . . . . . . . . . .
Leak Test Line Set and Indoor Coil . . . . . . . . . . . . . . .
Evacuating Line Set and Indoor Coil . . . . . . . . . . . . .
Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start−Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Servicing and Weighing In Refrigerant for Units
Delivered Void of Charge . . . . . . . . . . . . . . . . . . . . . . .
Optimizing System Refrigerant Charge . . . . . . . . . . .
System Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defrost System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Two−Stage Modulation Compressors Checks . . . . . .
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checklists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IMPORTANT
This unit must be matched with an indoor coil as
specified in Lennox XP16 Engineering Handbook.
Coils previously charged with HCFC−22 must be
flushed.

CAUTION
Physical contact with metal edges and corners while
applying excessive force or rapid motion can result in
personal injury. Be aware of, and use caution when
working near these areas during installation or while
servicing this equipment.
12/10

*2P1210*

Litho U.S.A.

1
1
2
2
3
3
3
5
6
8
9
11
14
15
16
17
18
23
24
26
30
34
40
40
42

Shipping and Packing List
Check unit for shipping damage. Consult last carrier
immediately if damage is found.
1 − Assembled outdoor unit

General
The XP16 outdoor unit uses HFC−410A refrigerant. This
unit must be installed with a matching indoor blower coil
and line set as outlined in the XP16 Lennox Engineering
Handbook. Elite® Series outdoor units are designed for
use in check / expansion valve (CTXV) systems only and
are not to be used with other refrigerant flow control
devices. An indoor coil check / expansion valve approved
for use with HFC−410A must be ordered separately and
installed prior to operating the unit.
Page 1

506640−01

*P506640-01*

Model Number Identification
X P 16 −036 − 230 −05
Refrigerant Type
X = R−410A

Minor Revision Number
Voltage
230 = 208/230V−1ph−60hz

Unit Type
P = Heat Pump

Nominal Cooling Capacity
024 = 2 tons
036 = 3 tons
048 = 4 tons
060 = 5 tons

Series

Unit Dimensions − inches (mm)
C

DISCHARGE AIR

LIQUID LINE
CONNECTION

ELECTRICAL
INLETS

VAPOR LINE
CONNECTION

2 (51)
4−3/4
(121)

4−1/4
(108)

SIDE VIEW

1 (25)

UNIT SUPPORT
FEET

UNIT SUPPORT FEET

8−1/2
(216)

9−1/2
(241)

8−3/4
(222)

8−1/4
(210)

13−1/2
(343)

5−1/2
(140)

J
H

XP16 BASE WITH LEGS

XP16−024 BASE SECTION
Mode Number

XP16−024−230

35 (889)

27 (686)

28 (711)

−

XP16−036−230

39 (991)

30−1/2 (775)

35 (889)

13−7/8 (352)

7−3/4 (197)

3−1/4 (83)

27−1/8 (689)

3−5/8 (92)

4−1/2 (114)

20−5/8 (524)

XP16−048−230

35 (889)

35−1/2 (902)

39−1/2
(1003)
16−7/8 (429)

8−3/4 (222)

3−1/8 (79)

30−3/4 (781)

4−5/8 (117)

3−3/4 (95)

26−7/8 (683)

XP16−060−230

45 (1143 35−1/2 (902)

39−1/2
(1003)

Page 2

Typical Unit Parts Arrangement
FOR COIL SENSOR (RT21)
LOCATION SEE DETAIL A

COMPRESSOR

DUAL RUN CAPACITOR (C12)
(−024, −036 AND −048 ONLY)
SINGLE RUN CAPACITOR (C1)
(−060 ONLY)

DEMAND DEFROST
CONTROL (A108)

DISCHARGE LINE
SENSOR (RT28)
REVERSING
VALVE (L1)
TRUE SUCTION
PORT
HIGH PRESSURE
SWITCH (S4)
EXPANSION VALVE
SENSING BULB

CHECK /
EXPANSION
VALVE

LIQUID VALVE AND GAUGE
PORT / LIQUID LINE
CONNECTIONS
GROUND
LUG

SINGLE POLE
CONTACTOR
(K1)

AMBIENT
TEMPERATURE
SENSOR (RT13)

LIQUID LINE
BI−FLOW FILTER
DRIER
LOW PRESSURE
SWITCH (S87)

VAPOR VALVE AND GAUGE PORT /
SUCTION LINE CONNECTIONS

DETAIL A

XP16−048

XP16−036

COIL SENSOR − EIGHT HAIRPIN
UP FROM THE BOTTOM ON
INSIDE ROW.

COIL SENSOR − NINTH
HAIRPIN UP FROM THE
BOTTOM ON INSIDE
ROW.

XP16−060
COIL SENSOR −
SIXTH HAIRPIN UP
FROM THE BOTTOM
ON INSIDE ROW.

XP16−024
COIL SENSOR −THIRD
HAIRPIN DOWN FROM
THE TOP ON INSIDE
ROW.

Figure 1. Unit Parts Arrangement

Caps and Fasteners Torque Requirements

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
Corp.0807−L5 (C−08−1) for further details and
information.

When servicing or repairing HVAC equipment and
components, ensure the fasteners are appropriately
tightened. Table 1 list torque values for various caps and
fasteners.
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

Page 3
XP16 SERIES

Operating Gauge Set and Service Valves
USING MANIFOLD GAUGE SET
When checking the system charge, only use a manifold
gauge set that features low−loss anti−blow back fittings.

IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.

Manifold gauge set used for HFC−410A refrigerant
systems must be capable of handling the higher system
operating pressures. The manifold gauges should be rated
for:
S High side Pressure range of 0 − 800 pound−force per
square inch gauge (psig)
S Low side Use with 30" vacuum to 250 psig with
dampened speed to 500 psig
S Manifold gauge set hoses must be rated for use to 800
psig of pressure with a 4000 psig burst rating.

OPERATING SERVICE VALVES
The liquid and vapor line service valves are used for
refrigerant recovery, flushing, leak testing, evacuating,
weighing in refrigerant and optimizing system charge.
Each valve is equipped with a service port which has a
factory−installed valve core. Figure 2 provides information
on how to access and operate both angle− and ball−type
service valves.
Operating Angle−Type Service Valve:
1. Remove stem cap with an appropriately sized wrench.

HEX−HEAD
2 INSERT
EXTENSION HERE

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 to open
the service valve.
SERVICE PORT CAP

TO INDOOR
UNIT

SERVICE PORT CORE
SERVICE PORT
CORE

(VALVE STEM SHOWN OPEN)
INSERT HEX WRENCH HERE

TO INDOOR
UNIT

TO OUTDOOR UNIT

TO OUTDOOR
UNIT

VALVE STEM
SHOWN
CLOSED

When service valve stem is in the CLOSED position,
the service port is open to the line set and indoor unit.
STEM CAP

When service valve is OPEN, the service port is open to line set,
indoor and outdoor unit.

Operating Ball−Type Service Valve:

To Access Service Port:
A service port cap protects the service port core from
contamination and serves as the primary leak seal.

1. Remove stem cap with an appropriately sized wrench.

1. Remove service port cap with an appropriately sized
wrench.

2. Use an appropriately sized wrenched to open.

2. Connect gauge set to service port.

To open rotate stem
counterclockwise
90°.
To close rotate stem
clockwise 90°.

TO INDOOR UNIT

2 VALVE STEM
SERVICE PORT
SERVICE PORT CORE

1 REMOVE
STEM CAP

11 12
10
9
8
7 6

2
3
4

Without torque wrench: Finger tighten and use an appropriately sized
wrench to turn an additional 1/6 turn clockwise.
1/12 TURN

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:

SERVICE PORT CAP

1/6 TURN

5
3. When testing is completed, replace service port cap and
tighten as follows:
S With torque wrench: Finger tighten and torque cap per table 1.
S

BALL (SHOWN CLOSED)

TO OUTDOOR UNIT

1 REMOVE
STEM CAP

With Torque Wrench: Finger tighten and then
torque cap per table 1.

11 12 1
2
10
9
3
4
8
7 6 5

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−Type Service Valves

Page 4

Recovering Refrigerant from Existing System

DISCONNECT POWER
Disconnect all power to the existing outdoor unit at the disconnect
switch and/or main fuse box/breaker panel.

CONNECT MANIFOLD GAUGE SET
Connect a manifold gauge set, clean recovery cylinder and a
recovery machine to the service ports of the existing unit..

NOTE Use the recovery machine instructions to make
the correct manifold gauge set connections for recovery
refrigerant. The illustration below is a typical connection.

MAIN FUSE
BOX/BREAKER
PANEL

MANIFOLD GAUGES
DISCONNECT
SWITCH

RECOVERY MACHINE
LOW

CLEAN RECOVERY
CYLINDER

RECOVERING REFRIGERANT

HIGH

OUTDOOR UNIT

Remove existing HCFC−22 refrigerant using one of the following procedures:

METHOD 2 LIMITATIONS

METHOD 1:
Use Method 1 if the existing outdoor unit is not equipped with shut−off valves, or
if the unit is not operational and you plan to use the existing HCFC−22 to flush
the system.
Recover all HCFC−22 refrigerant from the existing system using a recovery
machine and clean recovery cylinder. Check gauges after shutdown to confirm
that the entire system is completely void of refrigerant.

S
S

METHOD 2:
Use Method 2 if the existing outdoor unit is equipped with manual shut−off valves,
and you plan to use new HCFC−22 refrigerant to flush the system.
Perform the following task:
A
Start the existing HCFC−22 system in the cooling mode and close the liquid line
valve.
B
Use the compressor to pump as much of the existing HCFC−22 refrigerant into
the outdoor unit until the outdoor system is full. Turn the outdoor unit main power
OFF and use a recovery machine to remove the remaining refrigerant from the
system.
NOTE It may be necessary to bypass the low pressure switches (if equipped) to
ensure complete refrigerant evacuation.
C
D

NOTE When using Method 2, the listed devices
below could prevent full system charge recovery into
the outdoor unit:

When the low side system pressures reach 0 psig, close the vapor line valve.
Check gauges after shutdown to confirm that the valves are not allowing
refrigerant to flow back into the low side of the system.

Outdoor unit’s high or low−pressure switches (if
applicable) when tripped can cycle the
compressor OFF.
Compressor can stop pumping due to tripped
internal pressure relief valve.

Compressor has internal vacuum protection that
is designed to unload the scrolls (compressor
stops pumping) when the pressure ratio meets a
certain value or when the suction pressure is as
high as 20 psig. (Compressor suction
pressures should never be allowed to go into
a vacuum. Prolonged operation at low suction
pressures will result in overheating of the
scrolls and permanent damage to the scroll
tips, drive bearings and internal seals.)
Once the compressor can not pump down to a lower
pressure due to any of the above mentioned system
conditions, shut off the vapor valve. Turn OFF the main
power to unit and use a recovery machine to recover
any refrigerant left in the indoor coil and line set.

Figure 3. Refrigerant Recovery

IMPORTANT
The Environmental Protection Agency (EPA) prohibits the intentional venting of HFC refrigerants during maintenance,
service, repair and disposal of appliance. Approved methods of recovery, recycling or reclaiming must be followed.

WARNING
Refrigerant can be harmful if it is inhaled. Refrigerant must be used and recovered responsibly.
Failure to follow this warning may result in personal injury or death.

Page 5
XP16 SERIES

New Outdoor Unit Placement
If additional elevation is necessary, raise the unit by
extending the height of the unit support feet. This may be
achieved by using a 2 inch (50.8mm) schedule 40 female
threaded adapter.

CAUTION
In order to avoid injury, take proper precaution when lifting heavy objects.
Remove existing outdoor unit prior to placement of new
outdoor unit. See Unit Dimensions on page 2 for sizing
mounting slab, platforms or supports. Refer to figure 4 for
mandatory installation clearance requirements.
POSITIONING CONSIDERATIONS
Consider the following when positioning the unit:
S 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.
S When possible, do not install the unit directly outside
a window. Glass has a very high level of sound
transmission. For proper placement of unit in relation
to a window see the provided illustration in figure 5,
detail A.

The specified coupling will fit snuggly into the recessed
portion of the feet. Use additional 2 inch (50.8mm)
Schedule 40 male threaded adaptors which can be
threaded into the female threaded adaptors to make
additional adjustments to the level of the unit.
NOTE Keep the height of extenders short enough to
ensure a sturdy installation. If it is necessary to extend
further, consider a different type of field−fabricated
framework that is sturdy enough for greater heights.
ROOF MOUNTING
Install the unit a minimum of 6 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. See figure 5, detail F for other roof top
mounting considerations.

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,
detail B.
NOTE If necessary for stability, anchor unit to slab as
described in figure 5, detail D.
ELEVATING THE UNIT
Units are outfitted with elongated support feet as illustrated
in figure 5, detail C.

NOTICE
Roof Damage!
This system contains both refrigerant and oil. Some
rubber roofing material may absorb 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.

CLEARANCE ON ALL SIDES INCHES (MILLIMETERS)
6 (152)

ACCESS PANEL
CONTROL PANEL
ACCESS
LOCATION
30 (762)

12 (305)

MINIMUM CLEARANCE
ABOVE UNIT

NOTES:

S
S

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).

LINE SET
CONNECTIONS

36 (914)

MINIMUM CLEARANCE BETWEEN TWO UNITS

24
(610)

Figure 4. Installation Clearances
Page 6

48 (1219)

DETAIL A Outside Unit Placement
Install unit away from windows.

DETAIL B Slab Mounting at Ground Level
Install unit level or, if on a slope, maintain slope tolerance of two (2)
degrees (or two inches per five feet [50 mm per 1.5 m]) away from
building structure.

BUILDING
STRUCTURE

MOUNTING
SLAB
TWO 90° ELBOWS INSTALLED IN LINE SET WILL
REDUCE LINE SET VIBRATION.

Elevated Slab Mounting

DETAIL C using Feet Extenders

GROUND LEVEL

DETAIL D Slab Side Mounting
#10 1/2" LONG SELF−DRILLING
SHEET METAL SCREWS

COIL

STABILIZING BRACKET (18 GAUGE
METAL 2" WIDTH; HEIGHT AS
REQUIRED)

BASE PAN

#10 1−1/4" LONG HEX HD SCREW
AND FLAT WASHER
CORNER POST
BASE

Concrete slab use two plastic anchors (hole
drill 1/4")
Wood or plastic slab no plastic anchor (hole
drill 1/8")

Stabilizing bracket (18 gauge metal 2" (50.8mm) width; height as required); bend to form
right angle as exampled below.

LEG DETAIL
2" (50.8MM) SCH 40
FEMALE THREADED
ADAPTER

DETAIL F Roof Top Mounting
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 barrier 24
inches (610 mm) from the sides of the unit in the direction of prevailing winds as illustrated.

2" (50.8MM) SCH 40
MALE THREADED
ADAPTER

PREVAILING WINTER WINDS

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.

WIND BARRIER
INLET AIR

DETAIL E

Deck Top Mounting

MINIMUM ONE
One bracket per side
PER SIDE
(minimum). For extra
stability, two brackets per
side, two inches (51mm)
from each corner.
SAME FASTENERS AS
SLAB SIDE MOUNTING.

INLET AIR

FOR EXTRA
STABILITY

INLET AIR

Figure 5. Placement, Slab Mounting and Stabilizing Unit
Page 7
XP16 SERIES

Removing and Installing Panels
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.

IMPORTANT! DO NOT ALLOW PANELS TO HANG ON UNIT BY TOP TAB. TAB IS FOR
ALIGNMENT AND NOT DESIGNED TO SUPPORT WEIGHT OF PANEL.
PANEL SHOWN SLIGHTLY ROTATED TO ALLOW TOP TAB TO EXIT (OR
ENTER) TOP SLOT FOR REMOVING (OR INSTALLING) PANEL.

SCREW
HOLES
LIP

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 A and 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.

Detail A

Detail B

ROTATE IN THIS DIRECTION;
THEN DOWN TO REMOVE
PANEL

Detail C

ANGLE MAY BE TOO
EXTREME

HOLD DOOR FIRMLY TO THE HINGED
SIDE TO MAINTAIN
FULLY−ENGAGED TABS

PREFERRED ANGLE
FOR INSTALLATION

Detail D

MAINTAIN MINIMUM PANEL ANGLE (AS CLOSE TO
PARALLEL WITH THE UNIT AS POSSIBLE) WHILE
INSTALLING PANEL.

Figure 6. Removing and Installing Panels

WARNING
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.

Page 8

Line Set Requirements
This section provides information on: installation of new or
replacement line set.
S Adding Polyol ester oil requirements
S New or replacement line set installation
S Using existing line set.

Model (XP16) 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.

USING EXISTING LINE SET

ADDING POLYOL ESTER OIL REQUIREMENTS

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
(POE) for line set lengths up to 50 feet. Recommend
adding oil to system based on the amount of refrigerant
charge in the system. Systems with 20 pounds or less of
refrigerant required no oil to be added.
For systems over 20 pounds − add one ounce for every five
(5) pounds of HFC−410A refrigerant.

Things to consider:
S Liquid line that meter the refrigerant, such as RFC1
liquid line, must not be used in this application.
S Existing line set of proper size as listed in table 2 may
be reused.
S If system was previously charged with HCFC−22
refrigerant, then existing line set must be flushed (see
Flushing Line Set and Indoor Coil on page 14).
If existing line set is being used, then proceed to Brazing
Connections on page 11.

Recommended topping−off POE oils are Mobil EAL
ARCTIC 22 CC or ICI EMKARATEt RL32CF.
NEW OR REPLACEMENT LINE SET INSTALLATION
Field refrigerant piping consists of both liquid and vapor
lines from the outdoor unit to the indoor coil. Use Lennox
L15 (sweat, non−flare) series line set, or field−fabricated
refrigerant line sizes as specified in table 2.
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
refrigerant lines will not create unnecessary vibration and
subsequent sounds. See figure 7 for recommended
installation practices.

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 Line Set and Indoor Coil on page
13.

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.

NOTE When installing refrigerant lines longer than 50
feet, see the Lennox Refrigerant Piping Design and
Fabrication Guidelines, CORP. 9351−L9, or contact
Lennox Technical Support Product Applications for
assistance. To obtain the correct information from Lennox,
be sure to communicate the following information:
Table 2. Refrigerant Line Set Inches (mm)
Model
XP16−024−230

Field Connections

Recommended Line Set

Liquid Line

Suction Line

Liquid Line

Suction Line

L15 Line Set

3/8" (10 mm)

3/4" (19 mm)

3/8" (10 mm)

3/4" (19 mm)

L15−41 15 ft. − 50 ft. (4.6m − 15 m)

3/8" (10 mm)

7/8" (22 mm)

3/8" (10 mm)

7/8" (22 mm)

L15−65 15 ft. − 50 ft. (4.6 m − 15 m)

3/8" (10 mm)

1−1/8" (29 mm)

3/8" (10 mm)

1−1/8" (29 mm)

Field Fabricated

XP16−036−230
XP16−048−230
XP16−060−230

NOTE Some applications may required a field provided 7/8" to 1−1/8" adapter

Page 9
XP16 SERIES

Line Set Isolation The following illustrations are examples of proper refrigerant line set isolation:

REFRIGERANT LINE SET INSTALLING
VERTICAL RUNS (NEW CONSTRUCTION SHOWN)

REFRIGERANT LINE SET TRANSITION
FROM VERTICAL TO HORIZONTAL

ANCHORED HEAVY NYLON
WIRE TIE OR AUTOMOTIVE
MUFFLER-TYPE HANGER

AUTOMOTIVE
MUFFLER-TYPE HANGER

OUTSIDE WALL

LIQUID LINE

VAPOR LINE

WALL
STUD

WIRE TIE
INSIDE WALL

STRAP
WOOD BLOCK
BETWEEN STUDS

STRAP LIQUID LINE TO
VAPOR LINE

NON−CORROSIVE
METAL SLEEVE
WIRE TIE

LIQUID LINE
NON−CORROSIVE
METAL SLEEVE

WOOD BLOCK
VAPOR LINE − WRAPPED
IN ARMAFLEX

WIRE TIE
STRAP

REFRIGERANT LINE SET INSTALLING
HORIZONTAL RUNS

SLEEVE

To hang line set from joist or rafter, use either metal strapping material
or anchored heavy nylon wire ties.
WIRE TIE (AROUND
VAPOR LINE ONLY)

VAPOR LINE WRAPPED
WITH ARMAFLEX

8 FEET (2.43 METERS)
STRAPPING
MATERIAL (AROUND
VAPOR LINE ONLY)

OUTSIDE
WALL
FLOOR JOIST OR
ROOF RAFTER

LIQUID
LINE

TAPE OR
WIRE TIE
8 FEET (2.43 METERS)
PVC
PIPE

NON−CORROSIVE
METAL SLEEVE
TAPE OR
WIRE TIE

CAULK
FIBERGLASS
INSULATION

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.

NOTE Similar installation practices should be used if line set is
to be installed on exterior of outside wall.

FLOOR JOIST OR
ROOF RAFTER

Figure 7. Line Set Installation

Page 10

Brazing Connections
Use the procedures outline in figures 8 and 9 for brazing line set connections to service valves.

WARNING

IMPORTANT

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.

Allow braze joint to cool before removing the wet rag
from the service valve. Temperatures above 250ºF can
damage valve seals.

IMPORTANT

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).

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 explosion, that could result in property
damage, personal injury or death.

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 11
XP16 SERIES

CUT AND DEBUR

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.

CAP AND CORE REMOVAL
Remove service cap and core from
both the suction / vapor and liquid line
service ports.

CUT AND DEBUR
SERVICE PORT
CAP

SERVICE
PORT
CORE

LINE SET SIZE MATCHES
SERVICE VALVE CONNECTION
SERVICE
PORT
CORE

SERVICE VALVE
CONNECTION

SERVICE
PORT CAP

COPPER TUBE
STUB
LIQUID LINE SERVICE
VALVE

REDUCER

LINE SET SIZE IS SMALLER
THAN CONNECTION

SUCTION / VAPOR LINE
SERVICE VALVE

DO NOT CRIMP SERVICE VALVE
CONNECTOR WHEN PIPE IS
SMALLER THAN CONNECTION

REFRIGERANT LINE

ATTACH THE MANIFOLD GAUGE SET FOR BRAZING LIQUID AND SUCTION / VAPOR LINE SERVICE
VALVES
Flow regulated nitrogen (at 1 to 2 psig) through the low−side refrigeration gauge set into the liquid line service port valve, and out of the suction /
vapor line service port valve.
A
Connect gauge set low pressure side to
liquid line service valve (service port).
USE REGULATOR TO FLOW
B

Connect gauge set center port to bottle of
nitrogen with regulator.

Remove core from valve in suction / vapor
line service port to allow nitrogen to escape.

SUCTION / VAPOR SERVICE PORT MUST BE
OPEN TO ALLOW EXIT POINT FOR NITROGEN

LOW

HIGH

NITROGEN AT 1 TO 2 PSIG.

ATTACH
GAUGES

SUCTION /
VAPOR LINE
SERVICE
VALVE

VAPOR LINE

OUTDOOR
UNIT

INDOOR
UNIT

NITROGEN
LIQUID LINE

LIQUID LINE SERVICE
VALVE

WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.

Figure 8. Brazing Procedures

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).

Page 12

4
5
6

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.

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 manifold gauge set connections

BRAZE LINE SET
Wrap both service valves with water saturated cloths as illustrated here and as mentioned in step 4, before brazing to line set. Water
saturated cloths must remain water saturated throughout the brazing and cool−down process.

LIQUID LINE SERVICE VALVE

WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.

IMPORTANT Allow

braze joint to cool. Apply
additional water saturated cloths to help cool brazed
joint. Do not remove water saturated cloths until piping
has cooled. Temperatures above 250ºF will damage
valve seals.

WATER SATURATED
CLOTH

LIQUID LINE

WARNING
SUCTION / VAPOR LINE
SERVICE VALVE

1. 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 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.

WHEN BRAZING LINE SET TO
SERVICE VALVES, POINT FLAME
AWAY FROM SERVICE VALVE.

SUCTION / VAPOR LINE
WATER SATURATED
CLOTH

PREPARATION FOR NEXT STEP
After all connections have been brazed, disconnect manifold gauge set from service ports. Apply additional water saturated cloths to both
service valves to cool piping. Once piping is cool, remove all water saturated cloths.

Figure 9. Brazing Procedures (continued)

Page 13
XP16 SERIES

Indoor Refrigerant Metering Device Removal and Flushing Line Set and Indoor Coil
Flushing is only required when the existing system used HCFC−22 refrigerant. If the existing system used HFC−410a, then
remove the original indoor coil metering device and proceed to Installing New Indoor Metering Device on page 15.

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)

DISTRIBUTOR TUBES
LIQUID LINE ORIFICE HOUSING

DISTRIBUTOR
TUBES

STUB END
LIQUID LINE
ORIFICE
HOUSING

CHECK
EXPANSION
VALVE
TEFLON®
RING

TEFLON® RING
FIXED ORIFICE
BRASS NUT

TEFLON®
RING

DISTRIBUTOR
ASSEMBLY

REMOVE AND DISCARD
WHITE TEFLON® SEAL
(IF PRESENT)

A
B
C

D
E

LIQUID LINE
ASSEMBLY WITH
BRASS NUT

CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE

D
E

INVERTED HCFC−22
CYLINDER CONTAINS
CLEAN HCFC−22 TO BE
USED FOR FLUSHING.

GAUGE
MANIFOLD

LOW

OPENED
EXISTING
INDOOR
UNIT

VAPOR
LIQUID

CLOSED

LIQUID LINE SERVICE
VALVE
RECOVERY
CYLINDER

G
H

HIGH

NEW
OUTDOOR
UNIT

VAPOR LINE
SERVICE VALVE

INLET
DISCHARGE
RECOVERY MACHINE

A
B
C
D

MALE EQUALIZER
LINE FITTING
SENSING BULB

Inverted HCFC−22 cylinder with clean refrigerant to the vapor service
valve.
HCFC−22 gauge set (low side) to the liquid line valve.
HCFC−22 gauge set center port to inlet on the recovery machine with an
empty recovery tank to the gauge set.
Connect recovery tank to recovery machines per machine instructions.

VAPOR
LINE

FLUSHING LINE SET
The line set and indoor unit coil must be flushed with at least the
same amount of clean refrigerant that previously charged the
system. Check the charge in the flushing cylinder before
proceeding.
A
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
B
set and indoor unit coil.
B
Invert 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.
C
After all of the liquid refrigerant has been recovered, 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.
D
Close the valve on the inverted HCFC−22 drum and the gauge
set valves. Pump the remaining refrigerant out of the recovery
machine and turn the machine off.

Figure 10. Removing Indoor Refrigerate Metering Device and Flushing Procedures
Page 14

LIQUID
LINE

On fully cased coils, remove the coil access and plumbing panels.
Remove any shipping clamps holding the liquid line and distributor
assembly.
Disconnect the equalizer line from the check expansion valve
equalizer line fitting on the vapor line.
Remove the vapor line sensing bulb.
Disconnect the liquid line from the check expansion valve at the liquid
line assembly.
Disconnect the check expansion valve from the liquid line orifice
housing. Take care not to twist or damage distributor tubes during this
process.
Remove and discard check expansion valve and the two Teflon® rings.
Use a field−provided fitting to temporary reconnect the liquid line to the
indoor unit’s liquid line orifice housing.

TANK
RETURN

EQUALIZER
LINE

LIQUID LINE ASSEMBLY
(INCLUDES STRAINER)

On fully cased coils, remove the coil access and plumbing panels.
Remove any shipping clamps holding the liquid line and distributor assembly.
Using two wrenches, disconnect liquid line from liquid line orifice housing. Take care not to twist or damage distributor tubes during this process.
Remove and discard fixed orifice, valve stem assembly if present and A
Teflon® washer as illustrated above.
B
Use a field−provided fitting to temporary reconnect the liquid line to the
indoor unit’s liquid line orifice housing.
C

SENSING
LINE

Installing New Indoor Metering Device
This outdoor unit is designed for use in HFC−410A systems that use a check / expansion valve metering device (purchased
separately) at the indoor coil.
See the Lennox XP16 Engineering Handbook for approved check / expansion valve kit match−ups. The check / expansion
valve device can be installed either 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 (see figure 11).
INDOOR EXPANSION VALVE INSTALLATION
TWO PIECE
PATCH PLATE
(UNCASED
COIL ONLY)
DISTRIBUTOR
TUBES

(Uncased Coil Shown)
LIQUID LINE
ORIFICE
HOUSING

STUB
END

B
CHECK /
EXPANSION
VALVE
TEFLON®
RING

TEFLON®
RING

DISTRIBUTOR
ASSEMBLY

SENSING
LINE

EQUALIZER
LINE

LIQUID LINE
ASSEMBLY WITH
BRASS NUT

SENSING BULB INSTALLATION
A

MALE EQUALIZER LINE
FITTING (SEE
EQUALIZER LINE
INSTALLATION FOR
FURTHER DETAILS)

VAPOR
LINE

Sensing bulb insulation is
required if mounted external to
the coil casing.

1/2 Turn
Remove the field−provided fitting that temporarily
reconnected the liquid line to the indoor unit’s distributor
assembly.
11 12 1
2
Install one of the provided Teflon® rings around the 10
3
stubbed end of the check / expansion valve and lightly 9
4
lubricate the connector threads and expose surface of 8 7
6 5
the Teflon® ring with refrigerant oil.
Attach the stubbed end of the expansion valve to the
liquid line orifice housing. 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.
Place 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 refrigerant oil.
Attach 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.

Attach the vapor line sensing bulb in the proper
orientation as illustrated to the right using the clamp and
screws provided.

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 to the right.

BULB

FLARE NUT

ON LINES SMALLER THAN
7/8", MOUNT SENSING
BULB AT EITHER THE 3 OR
9 O’CLOCK POSITION.

VAPOR LINE

EQUALIZER LINE INSTALLATION

FLARE SEAL CAP

1/8 Turn

NOTE Confirm proper thermal contact between vapor line
11 12 1
and expansion bulb before insulating the sensing bulb once 10
2
LIQUID LINE
installed.
9
3
4
B
Connect the equalizer line from the check / expansion 8 7
5
6
valve to the equalizer vapor port on the vapor line. Finger
tighten the flare nut plus 1/8 turn (7 ft−lbs) as illustrated
below.

BULB

VAPOR LINE

COPPER FLARE
SEAL BONNET

MALE BRASS EQUALIZER
LINE FITTING

ON 7/8" AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O’CLOCK
POSITION. NEVER MOUNT ON
BOTTOM OF LINE.

BULB

NOTE NEVER MOUNT ON BOTTOM OF LINE.

VAPOR LINE

Figure 11. Installing Indoor Check / Expansion Valve

Page 15
XP16 SERIES

Leak Test Line Set and Indoor Coil

IMPORTANT
Leak detector must be capable of sensing HFC refrigerant.
CONNECT GAUGE SET
A

Connect an HFC−410A manifold gauge set high pressure hose to the
vapor valve service port.

LOW

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.
With both manifold valves closed, connect the cylinder of HFC−410A
refrigerant to the center port of the manifold gauge set.

HIGH
MANIFOLD GAUGE SET

OUTDOOR UNIT

NOTE Later in the procedure, the
HFC−410A container will be replaced by
the nitrogen container.

B
TO VAPOR
SERVICE VALVE

NITROGEN
HFC−410A

Figure 12. Manifold Gauge Set Connections for Leak Testing
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:
1. 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).
2. Open the high pressure side of the manifold to allow
HFC−410A into the line set and indoor unit. Weigh in
a trace amount of HFC−410A. [A trace amount is a
maximum of two ounces (57 g) refrigerant or three
pounds (31 kPa) pressure]. Close the valve on the
HFC−410A cylinder and the valve on the high pressure

Page 16

side of the manifold gauge set. Disconnect the
HFC−410A cylinder.
3. Connect a cylinder of dry nitrogen with a pressure
regulating valve to the center port of the manifold
gauge set.
4. Adjust dry nitrogen pressure to 150 psig (1034 kPa).
Open the valve on the high side of the manifold gauge
set in order to pressurize the line set and the indoor unit.
5. 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.
6. After leak testing disconnect gauges from service
ports.

Evacuating Line Set and Indoor Coil
Evacuating the system of non−condensables is critical for proper operation of the unit. Non−condensables are defined as any
gas that will not condense under temperatures and pressures present during operation of an air conditioning system.
Non−condensables and water suction combine with refrigerant to produce substances that corrode copper piping and
compressor parts.
CONNECT GAUGE SET

NOTE Remove cores from service valves (if not already done).
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
OUTDOOR
set to liquid line service valve
UNIT
C
Connect micron gauge available
connector on the 1/4 SAE in−line tee.
A
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.

LOW

MANIFOLD
GAUGE SET

A34000 1/4 SAE TEE WITH
SWIVEL COUPLER
500

MICRON
GAUGE

TO VAPOR
SERVICE VALVE

NITROGEN

HFC−410A

HIGH

B
VACUUM PUMP
TO LIQUID LINE
SERVICE VALVE

EVACUATE THE SYSTEM
A
B

NOTE The term absolute pressure means the total actual pressure within a given volume or system, above the absolute zero of
pressure. Absolute pressure in a vacuum is equal to atmospheric pressure minus vacuum pressure.
When the absolute pressure reaches 23,000 microns (29.01 inches of mercury), perform the following:

S
S
S
S
S
S

D
E

RECOMMEND

MINIMUM 3/8" HOSE
Open both manifold valves and start the vacuum pump.
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.

Close manifold gauge valves
Close valve on vacuum pump and turn off vacuum pump
Disconnect manifold gauge center port hose from vacuum pump
Attach manifold center port hose to a dry nitrogen cylinder with pressure regulator set to 150 psig (1034 kPa) and purge the hose.
Open manifold gauge valves to break the vacuum in the line set and indoor unit.

Close manifold gauge valves.
Shut off the dry nitrogen cylinder and remove the manifold gauge hose from the cylinder. Open the manifold gauge valves to release the
dry nitrogen from the line set and indoor unit.
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.
When the absolute pressure requirement above has been met, disconnect the manifold hose from the vacuum pump and connect it to an
upright cylinder of HFC−410A refrigerant. Open the manifold gauge valve 1 to 2 psig in order to release the vacuum in the line set and
indoor unit.
1/6 TURN
Perform the following:

S
S
S
S

Close manifold gauge valves.
11

Shut off HFC−410A cylinder.
Reinstall service valve cores by removing manifold hose from service valve. Quickly install cores with core
tool while maintaining a positive system pressure.
Replace stem caps and secure finger tight, then tighten an additional one−sixth (1/6) of a turn as illustrated.

10
9
8

2
4

Figure 13. Evacuating Line Set and Indoor Coil
Page 17
XP16 SERIES

Electrical Connections

IMPORTANT
Use a thermocouple or thermistor electronic vacuum
gauge that is calibrated in microns. Use an instrument
capable of accurately measuring down to 50 microns.

WARNING
Danger of Equipment Damage. Avoid deep vacuum
operation. Do not use compressors to evacuate a
system. Extremely low vacuums can cause internal
arcing and compressor failure. Damage caused by
deep vacuum operation will void warranty.
SIZE CIRCUIT AND INSTALL DISCONNECT
SWITCH

Refer to the unit nameplate for minimum circuit ampacity, and
maximum fuse or circuit breaker (HACR per NEC). Install power
wiring and properly sized disconnect switch.

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)

INSTALL THERMOSTAT
Install room thermostat (ordered separately) on an inside wall
approximately in the center of the conditioned area and 5 feet
(1.5m) from the floor. It should not be installed on an outside wall
or where it can be affected by sunlight or drafts.

THERMOSTAT

MAIN FUSE BOX/
BREAKER PANEL
DISCONNECT
SWITCH

5 FEET
(1.5M)

NOTE Units are approved for use only with copper conductors.
Ground unit at disconnect switch or to an earth ground.

NOTE 24VAC, Class II circuit connections are made in the control
panel.

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.

Page 18

HIGH VOLTAGE FIELD WIRING

LOW VOLTAGE CONNECTIONS

LOW VOLTAGE (24V) FIELD WIRING

AWG# INSULATION TYPE

LESS THAN 100’ (30 METERS)

TEMPERATURE RATING

MORE THAN 100’ (30 METERS)

35ºC MINIMUM.

NOTE − For proper voltages, select thermostat wire (control wires)
gauge per table above.
NOTE − Do not bundle any excess 24VAC control wires inside
control box.
A Run 24VAC control wires through cutout with grommet.
B Run 24VAC control wires through wire tie.
C Make 24VAC control wire connections.
D Tighten wire tie to security 24V control wiring.

WIRE RUN LENGTH

NOTE − Wire tie provides low voltage wire strain relief and to maintain
separation of field installed low and high voltage circuits.
CUTOUT WITH
GROMMET
24V CONTROL WIRES

TIGHTEN WIRE TIE

Install low voltage wiring from outdoor to indoor unit and from thermostat to indoor unit as illustrated. See figures 14 and 15 for typical field
connections when connecting unit to either a CBX32MV or CBX40UHV in non−communicating mode. For connections to other Lennox air handlers
or furnaces, see the ComfortSense® 7000 installation instruction for further match component wiring illustrations.

HIGH VOLTAGE POWER SUPPLY CONNECTIONS

GROUND

NOTE − Any excess high voltage field wiring
should be trimmed and secured away from
any low voltage field wiring.

OUTDOOR UNIT
CONTROL BOX

NOTE − 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.
CONDUIT
CUTOUT
CONDUIT

Page 19
XP16 SERIES

HEAT PUMP UNIT
(TWO−STAGE)

CBX32MV
OR
CBX40UHV

COMFORTSENSET
7000

3
1

X2658 OUTDOOR SENSOR IS REQUIRED FOR OUTDOOR
TEMPERATURE DISPLAY, DEW POINT CONTROL, HEAT PUMP AND
DUAL FUEL BALANCE POINTS.
CONNECTED ON UNIT WITH LSOM. RESISTOR KIT (CAT # 47W97)
IS REQUIRED WHEN CONNECTING THE COMFORTSENSE 7000
WITH THE LSOM 2.
FIELD PROVIDED JUMPER BETWEEN Y2 OUT BL ON HEAT PUMP
TO Y2 ON CBX40UHV.

O. D.
SENSOR
(X2658)

AIR
HANDLER
CONTROL

2
L

L
Y1

R−O
HEAT
PUMP

CUT ON−BOARD LINK R −O.

T
C

R−DS
DEHUM
OR
HARMONY

CUT ON−BOARD LINK R−DS WHEN DEHUMIDIFICATION TERMINAL IS USED.

CUT FOR OPTION

Y1−Y2
2−STAGE
COMPR

CUT ON−BOARD LINK Y1−Y2 FOR TWO−STAGE HP

G
Y2
OUT
BL

IMPORTANT − USE CARE WHEN CUTTING LINKS TO
PREVENT DAMAGE TO CONTROL. SEE CBX40UHV
INSTALLATION INSTRUCTION FOR FURTHER DETAILS.

Figure 14. Typical Field Wiring Heat Pump Application with CBX32MV or CBX40UHV
CBX32MV OR
CBX40UHV

OUTDOOR UNIT

COMFORTSENSEt
7000 THERMOSTAT

RED
FAN RELAY (NOT REQUIRED
WITH SINGLE−SPEED
OUTDOOR FAN)
PURPLE

RED

OUTDOOR
SENSOR

BLACK
T

PURPLE

(X2658)
BLACK
YELLOW
BLUE
BROWN (NOT USED FOR APPLICATIONS WITHOUT LSOM
BLUE (NOT REQUIRED FOR SINGLE STAGE)

AIR
HANDLER
CONTROL
IMPORTANT − USE CARE WHEN CUTTING LINKS TO
PREVENT DAMAGE TO CONTROL. SEE CBX40UHV
INSTALLATION INSTRUCTION FOR FURTHER DETAILS.

CUT ON−BOARD LINK Y1−Y2 FOR TWO−STAGE A/C ONLY

CUT ON−BOARD LINK R −O.

CUT ON−BOARD LINK R−DS WHEN DEHUMIDIFICATION
TERMINAL IS USED.

Y1−Y2
2−STAGE
COMPR
R−O
HEAT
PUMP
R−DS
DEHUM
OR
HARMONY

Figure 15. Heat Pump Application Humiditrol ® and Second−Stage Outdoor Fan Relay Wiring with
CBX32MV or CBX40UHV
Page 20

CUT FOR OPTION

RESISTOR KIT (CAT # 47W97) IS REQUIRED
WHEN CONNECTING THE COMFORTSENSE
7000 WITH THE LSOM 2.

Figure 16. Typical Unit Wiring Diagram (−024, −036 and −048 Only)

Page 21
XP16 SERIES

Figure 17. Typical Unit Wiring Diagram (−060 Only)

Page 22

Figure 18. Typical Factory Wiring Diagram (No Field Modifications)

Unit Start−Up

IMPORTANT
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.

have consulted with the power company and the
voltage condition has been corrected.
6. Open both the liquid and vapor line service valves to
release the refrigerant charge contained in outdoor
unit into the system.
7. Use figure 19 to determine next step in system
preparation.
OPEN BOTH VAPOR AND LIQUID SERVICE
VALVE STEMS TO RELEASE
REFRIGERANT FROM OUTDOOR UNIT TO
SYSTEM.

UNIT START−UP
1. Rotate fan to check for binding.
2. Inspect all factory− and field−installed wiring for loose
connections.
3. Verify that the manifold gauge set is connected as
illustrated in figure 21. Use a temperature sensor
positioned near the liquid line service port as illustrated
in figure 21 which will be required later when using the
subcooling method for optimizing the system
refrigerant charge.
4. Replace the stem caps and tighten to the value listed
in table 1.
5. Check voltage supply at the disconnect switch. The
voltage must be within the range listed on the unit’s
nameplate. If not, do not start the equipment until you

REFRIGERANT
PRESENT

GO TO SERVICE AND WEIGH
IN REFRIGERANT CHARGE
FOR OUTDOOR UNITS
DELIVERED VOID OF CHARGE
ON PAGE 24.

YES

GO TO OPTIMIZING SYSTEM
REFRIGERANT CHARGE ON
PAGE 26.

Figure 19. Outdoor Unit Factory Charge

Page 23
XP16 SERIES

Service and Weigh In Refrigerant for Outdoor Units Delivered Void of Charge
The following procedures are only required if it has been determine that the new outdoor unit is void of charge. Skip to the
next section if refrigerant charge is present.
LEAK CHECK, REPAIR AND EVACUATE
If the outdoor unit is void of refrigerant, clean the system
using the procedure described below.

2. Connect the manifold gauge set’s low pressure side to
the true suction port.
3. Connect the manifold gauge set’s high pressure side
to the liquid line service port.

1. Leak check system using procedures provided on
page 16. Repair any leaks discovered during leak test.

4. Connect the center hose of the gauge set to a cylinder
of HFC−410A and purge the hose. Then, place the
cylinder upside down on a scale.

2. Evacuate the system using procedure provided in
figure 13.

5. Check that fan rotates freely.

3. Use nitrogen to break the vacuum and install a new
filter drier in the system.

6. Inspect all factory− and field−installed wiring for loose
connections.

4. Evacuate the system again using procedure in figure
12.

7. Open the high side manifold gauge valve and weigh in
liquid refrigerant. Use figure 20 in calculating the
correct weigh−in charge.

CONNECT MANIFOLD GAUGE SET AND WEIGH IN
CHARGE
After the evacuation procedure, reconnect the manifold
gauge set as illustrated in figure 21.

8. Close manifold gauge valves.
9. Monitor the system to determine the amount of
moisture remaining in the oil. It may be necessary to
replace the bi−flow filter drier several times to achieve
the required dryness level. If system dryness is not
verified, the compressor will fail in the future.
10. Continue to Optimizing System Refrigerant Charge
on page 26 to optimize the system charge using
subcooling method.

NOTE − Temperature sensor illustrated in figure 21 is not
required for initial system weigh in charging.
1. Close manifold gauge set valves and connect the
center hose to a cylinder of HFC−410A. Set for liquid
phase charging.

WEIGH−IN CHARGING
CALCULATING SYSTEM CHARGE FOR OUTDOOR UNIT VOID OF CHARGE
If the system is void of refrigerant, first, locate and repair any leaks and then weigh in the refrigerant charge into the unit. To calculate the total
refrigerant charge:
Amount specified on
nameplate

Additional charge specified per indoor
unit match listed on page 28.

Adjust amount. for variation in line set
length listed on line set length table below.

Total Charge

+
Refrigerant Charge per Line Set Length

LIQUID LINE SET DIAMETER

OUNCES PER 5 FEET (G PER 1.5 M) ADJUST FROM 15 FEET
(4.6 M) LINE SET*

3/8" (9.5 MM)

3 OUNCE PER 5’ (85 G PER 1.5 M)

*If line length is greater than 15 ft. (4.6 m), add this amount. If line length is less than 15 ft. (4.6 m), subtract
this amount.

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.
NOTE The above nameplate is for illustration purposes only. Go to actual nameplate on outdoor unit for charge information.

Figure 20. Using HFC−410A Weigh In Method

Page 24

GAUGE SET

MANIFOLD GAUGE SET
HIGH

LOW

CONNECTIONS FOR OPTIMIZING SYSTEM CHARGE
SUCTION PORT
B TRUE
CONNECTION

OUTDOOR UNIT

NOTE Refrigerant tank should be
turned right−side−up to deliver vapor
during charge optimizing procedure.
REFRIGERANT
TANK

CHARGE IN
LIQUID PHASE
DIGITAL SCALE

TO LIQUID
LINE SERVICE
VALVE

TEMPERATURE SENSOR
(LIQUID LINE)

D
TEMPERATURE SENSOR (USE FOR
SUBCOOLING METHOD)

INSIDE OUTDOOR UNIT

Close manifold gauge set valves and connect the center hose to a cylinder of HFC−410A. Set for liquid phase charging.

Connect the manifold gauge set’s low pressure side to the true suction port.

Connect the manifold gauge set’s high pressure side to the liquid line service port.

Position temperature sensor on liquid line near liquid line service port (use only for subcooling method).

Figure 21. Gauge Set Connections for Adding Refrigerant

DISTRIBUTOR

OUTDOOR UNIT

NOTE − ARROWS INDICATE DIRECTION
OF REFRIGERANT FLOW
REVERSING VALVE

CHECK / EXPANSION
VALVE
OUTDOOR
COIL

INDOOR UNIT

BI−FLOW FILTER / DRIER
MUFFLER

TRUE SUCTION
PORT
LIQUID LINE
SERVICE PORT

VAPOR
SERVICE
PORT

COMPRESSOR

CHECK / EXPANSION VALVE

NOTE − Use gauge ports on vapor line valve and liquid valve for evacuating refrigerant lines and
indoor coil. Use true suction port to measure vapor pressure during charging.

INDOOR
COIL

Figure 22. Heat Pump Cooling Cycle

Page 25
XP16 SERIES

Optimizing System Refrigerant Charge
This section provides instructions on optimizing the
system charge. This section includes:
S Optimizing procedure
S Adjusting indoor airflow
S Using subcooling method
S Approved matched components, targeted subcooling
(SC) values and add charge values
S Normal operating pressures
S Temperature pressures
OPTIMIZING PROCEDURE
1. Move the low−side manifold gauge hose from the
vapor line service valve to the true suction port (see
figure 21).
2. Set the thermostat for either cooling or heating
demand. Turn on power to the indoor unit and close
the outdoor unit disconnect switch to start the unit.

efficiency. Make any air flow adjustments before
continuing with the optimizing procedure.
5. Use subcooling method to optimize the system
charge (see figure 24). Adjust charge as necessary.
ADJUSTING INDOOR AIRFLOW
Heating Mode Indoor Airflow Check
(Only use when indoor unit has electric heat)
Indoor blower airflow (CFM) may be calculated by
energizing electric heat and measuring:
S Temperature rise between the return air and supply air
temperatures at the indoor coil blower unit,
S Measuring voltage supplied to the unit,
S Measuring amperage being drawn by the heat unit(s).
Then, apply the measurements taken in the following
formula to determine CFM:
Amps x Volts x 3.41

3. Allow unit to run for five minutes to allow pressures to
stabilize.
4. Check the airflow as instructed under Adjusting Indoor
Airflow to verify or adjust indoor airflow for maximum

CFM =

1.08 x Temperature rise (F)

Cooling Mode Indoor Airflow Check
Check airflow using the Delta−T (DT) process using figure
23.

ADJUSTING INDOOR AIRFLOW
Temp.
of air
entering
indoor
coil ºF

DT
24
23
22
21

20 20 19 18 17 17 16 15 15 14 13 12 11 10

70
Wet−bulb ºF

19 19 18 18 17 17 16 15 15 14 13 12 11 10
57 58 59 60 61 62 63 64 65 66 67 68 69 70

Dry−bulb

80
78
76
74

24
23
22
21

23
22
21
20

23
22
21
19

22
21
20
19

22
21
19
18

22
20
19
17

20
19
18
16

19
18
17
16

18
17
16
15

17
16
15
14

16
15
14
13

15
14
13
12

B
C
53º

A
72º

TDrop
19º
air flow

air flow

DRY
BULB

B
64º

DRY
BULB

1. Determine the desired DTMeasure entering air temperature using dry bulb (A) and wet bulb (B). DT is the intersecting value of A and B in the table (see triangle).
2. Find temperature drop across coilMeasure the coil’s dry

bulb entering and leaving air temperatures (A and C). Temperature Drop Formula: (TDrop) = A minus C.
3. Determine if fan needs adjustmentIf the difference between
the measured TDrop and the desired DT (TDrop–DT) is within
+3º, no adjustment is needed. See examples: Assume DT =
15 and A temp. = 72º, these C temperatures would necessitate stated actions:
Cº TDrop –
DT = ºF ACTION
53º
58º
62º

All temperatures are
expressed in ºF

INDOOR
COIL

WET
BULB

19
14
10

–
–
–

15
15
15

=
=
=

4 Increase the airflow
−1 (within +3º range) no change
−5 Decrease the airflow

4. Adjust the fan speedSee indoor unit instructions to in-

crease/decrease fan speed.
Changing air flow affects all temperatures; recheck temperatures to confirm that the temperature drop and DT are within
+3º.

Figure 23. Checking Airflow over Indoor Coil Using Delta−T Formula

Page 26

OPTIMIZE CHARGE USING SUBCOOLING METHOD
1. Check liquid and vapor line pressures. Compare pressures with either second−stage
heat or cooling mode normal operating pressures listed in table 7. Table 7 is a general
guide and expect minor pressures variations. Significant pressure differences may
indicate improper charge or other system problem.
USE
COOLING
MODE
60ºF
(15ºC)

2. Decide whether to use cooling or heating mode based on current outdoor ambient
temperature:
A

Use COOLING MODE when:

S
S

Outdoor ambient temperature is 60°F (15.5°C) and above.
Indoor return air temperature range is between 70 to 80°F (21−27°C). This
temperature range is what the target subcooling values are base upon in
tables 3 through 6.
If indoor return air temperature is not within reference range, set thermostat to
cooling mode and a setpoint of 68ºF (20ºC). This should place the outdoor unit
into second−stage (high−capacity) cooling mode. When operating and
temperature pressures have stabilized, continue to step 3.

USE
HEATING
MODE

Use HEATING MODE when:

S
S

Outdoor ambient temperature is 59°F (15.0°C) and below.
Indoor return air temperature range is between 65−75°F (18−24°C). This
temperature range is what the target subcooling values are base upon in
tables 3 through 6.
If indoor return air temperature is not within reference range, set thermostat to
heating mode and a setpoint of 77ºF (25ºC). This should place the outdoor unit
into second−stage (high−capacity) heating mode. When operating and
temperature pressures have stabilized, continue to step 3.
3. Read the liquid line pressure; then find its corresponding temperature pressure listed
in table 8 and record it in the SATº space to the left.
4. Read the liquid line temperature; record in the LIQº space to the left.

SATº
5. Subtract LIQº temperature from SATº temperature to determine subcooling; record
it in SCº space to the left..

LIQº

–

SCº

6. Compare SCº results with tables 3 through 6 (either Heating or Cooling mode
column), also consider any additional charge required for line set lengths longer than
15 feet and/or unit matched component combinations (Add Charge column).
7. If subcooling value is:
A
B

GREATER than shown for the applicable unit match component, REMOVE
refrigerant;
LESS than shown for the applicable unit match component, ADD refrigerant.

8. If refrigerant is added or removed, repeat steps 3 through 6 to verify charge.
9. Close all manifold gauge set valves and disconnect gauge set from outdoor unit.
10. Replace the stem and service port caps and tighten as specified in Operating Service
Valves on page 2.
11. Recheck voltage while the unit is running. Power must be within range shown on the
nameplate.
Figure 24. Using HFC−410A Subcooling Method Second Stage (High Capacity)

Page 27
XP16 SERIES

APPROVED MATCHED SYSTEM COMPONENTS, TARGETED SUBCOOLING (SC) VALUES AND
ADD CHARGE VALUES
Listed below are the approved matched system components (air handlers and indoor coils), targeted subcooling and
add charge values for the XP16. This information is also listed on the unit charging sticker located on the outdoor unit
access panel.
Subcooling values listed in the following tables are based
on outdoor ambient air temperature of:
S 60°F (15.5°C) and above for cooling mode
S 59°F (15.0°C) and below for heating mode.
Table 3. XP16−024−230
Indoor Air Handers
and Coils

Heating
Mode
+5ºF

Cooling
Mode
+1ºF

Subcooling

*Add Charge
lb.

oz.

Table 5. XP16−048−230
Indoor Air Handers
and Coils

Heating
Mode
+5ºF

CBX26UH−048−230

CBX27UH−048−230
CBX27UH−060−230

Cooling
Mode
+1ºF

Subcooling

*Add Charge
lbs.

oz.

CBX32M−048

CBX26UH−024

CBX32M−060

CBX27UH−024−230

CBX32MV−048

CBX27UH−030−230

CBX32MV−060

CBX32MV−024/030

CBX32MV−068

CBX32MV−036

CBX40UHV−048

CBX40UHV−024

CBX40UHV−060

CBX40UHV−030

CH23−68

CBX40UHV−036

CH33−49C

CH33−31B

CH33−50/60C

CR33−30/36A/B/C

CH33−60D

CX34−31A/B

CH33−62D

CX34−38A/B

CR33−50/60C

CR33−60D

CX34−60D

CX34−62D

CX34−62C

Table 4. XP16−036−230
Indoor Air Handers
and Coils

Heating
Mode
+5ºF

Cooling
Mode
+1ºF

Subcooling

*Add Charge
lbs.

oz.

CBX26UH−036

CBX27UH−036−230

CBX27UH−042−230

CBX32M−036

CBX32MV−036

CBX32MV−048

CBX40UHV−030

CBX40UHV−036

CBX40UHV−042

CBX40UHV−048

CH33−43B

CH33−48C

CH33−43C

CR33−48B/C

CX34−43B/C

CX34−50/60C

Table 6. XP16−060−230
Indoor Air Handers
and Coils

Heating
Mode
+5ºF

Cooling
Mode
+1ºF

Subcooling

*Add Charge
lbs.

oz.

CBX26UH−060

CBX27UH−060−230

CBX32M−060

CBX32MV−060

CBX32MV−068

CBX40UHV−060

CH23−682

CH33−50/60C

CH33−62D

CR33−50/60C

CR33−60D

CX34−62C

CX34−62D

*Amount of charge required in additional to charge shown on unit
nameplate. (Remember to consider line set length difference.)

Page 28

NORMAL OPERATING PRESSURES
Use the following tables to perform maintenance checks; it
is not a procedure for charging the system. Minor
variations in these pressures may be due to differences in
installations. Significant deviations could mean that the
system is not properly charged or that a problem exists
with some component in the system.

TEMPERATURE PRESSURES
Compute subcooling by determining saturated
condensing temperature from temperature pressure
chart. Subtract from liquid temperature entering TXV.
Table 8. HFC−410A Temperature (°F) −
Pressure (Psig)
°F

Psig

°F

Psig

°F

Psig

°F

Psig

100.8

178.5

290.8

125

445.9

102.9

181.6

295.1

126

451.8

Table 7. Normal Operating Pressures*

105.0

184.3

299.4

127

457.6

Normal Operating Pressures − Cooling

107.1

187.7

303.8

128

463.5

109.2

190.9

308.2

129

469.5

111.4

194.1

312.7

130

475.6

113.6

197.3

100

317.2

131

481.6

115.8

200.6

101

321.8

132

487.8

Typical pressures only, expressed in psig (liquid +/− 10
and vapor +/− 5 psig); matched indoor component (air
handler or coil), indoor air quality, and indoor load will
cause the pressures to vary.

XP16
F
(C)**

−024
Liq

−036

Vap

Liq

−048

Vap

Liq

−060

Vap

Liq

Vap

First Stage (Low Capacity) Pressure
65
(18.3)

226

144

220

141

224

143

230

137

75
(23.9)

260

145

254

144

259

143

267

139

118.0

203.9

102

326.4

133

494.0

85
(29.4)

301

148

295

148

302

147

311

141

120.3

207.2

103

331.0

134

500.2

95
(35.0)

346

151

340

150

346

149

357

144

122.6

210.6

104

335.7

135

506.5

105
(40.6)

396

153

389

153

396

152

398

147

125.0

214.0

105

340.5

136

512.9

115
(46.1)

127.3

217.4

106

345.3

137

519.3

451

156

444

156

450

155

453

149
45

129.7

220.9

107

350.1

138

525.8

132.2

224.4

108

355.0

139

532.4

134.6

228.0

109

360.0

140

539.0

137.1

231.6

110

365.0

141

545.6

139.6

235.3

111

370.0

142

552.3

Second Stage (High Capacity) Pressure
65
(18.3)

241

140

232

129

238

138

232

131

75
(23.9)

279

142

269

136

278

140

276

133

85
(29.4)

321

144

312

140

321

142

320

136

95
(35.0)

369

146

346

142

372

144

367

138

142.2

239.0

112

375.1

143

559.1

105
(40.6)

421

148

409

145

424

147

421

141

144.8

242.7

113

380.2

144

565.9

115
(46.1)

480

151

465

148

481

149

479

144

147.4

246.5

114

385.4

145

572.8

150.1

250.3

115

390.7

146

579.8

152.8

254.1

116

396.0

147

586.8

155.5

258.0

117

401.3

148

593.8

158.2

262.0

118

406.7

149

601.0

161.0

266.0

119

412.2

150

608.1

163.9

270.0

120

417.7

151

615.4

166.7

274.1

121

423.2

152

622.7

169.6

278.2

122

428.8

153

630.1

172.6

282.3

123

434.5

154

637.5

175.4

286.5

124

440.2

155

645.0

Normal Operating Pressures − Heating
First Stage (Low Capacity) Pressure
50
(10)

312

112

350

115

336

114

385

108

60
(15.5)

330

130

372

136

363

135

414

126

Second Stage (High Capacity) Pressure
20
(−7.0)

299

321

289

332

30
(−1.0)

312

347

294

349

40
(4.4)

325

367

321

361

50
(10)

344

110

387

110

341

110

383

60
(15.5)

358

128

395

131

361

128

425

122

** Temperature of air entering outdoor coil.

Page 29
XP16 SERIES

UNIT COMPONENTS

System Operation

IMPORTANT
Some scroll compressor have 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.
This section addresses:
S Unit components (sensors, temperature switch,
pressure switches and demand defrost control)
S Second−stage operation

Demand Defrost Control (A108)
The demand defrost control measures differential
temperatures to detect when the system is performing
poorly because of ice build−up on the outdoor coil. The
controller self−calibrates when the defrost system starts
and after each system defrost cycle. The demand defrost
control’s: components are shown in figure 25.

Demand defrost control connections, jumpers and
LED locations are shown in figure 25.

Demand defrost control connections, jumpers and
LED descriptions are listed on table 9.

Demand defrost control status, fault and lockout LEDs
are listed in table 10.

TEST PINS (P1)
LOW AMBIENT
THERMOSTAT PINS
(P3)

DEFROST TERMINATION
PIN SETTINGS (P1)

SENSOR PLUG IN
(COIL AND
AMBIENT
SENSORS) (P4)
DIAGNOSTIC LEDS
(DS1 AND DS2)

DELAY PINS
(P5)

24V TERMINAL STRIP
CONNECTIONS (P2)

REVERSING VALVE
(O OUT)

PRESSURE SWITCH
CIRCUIT
CONNECTIONS

Note − Component locations vary by board manufacturer.

Figure 25. Demand Defrost Control (A108)

Page 30

Table 9. Demand Defrost Control (A108) Inputs, Outputs and Configurable Settings
Control
Locations

Control Label or
Description

Purpose

Function

TEST

Test Mode

See Test Mode on page 39 for further details.

50, 70, 90, 100

Defrost Temperature
Termination Shunt (Jumper)
Pins

The demand defrost control as illustrated in figure 25 has valid selections
which are: 50, 70, 90, and 100°F (10, 21, 32 and 38°C). The shunt
termination pin is factory set at 50°F (10°C). If the temperature shunt is
not installed, the default termination temperature is 90°F (32°C).

24VAC Thermostat Input /
Output

24VAC input / output from indoor thermostat to indoor unit.

24VAC Common

24VAC common

Thermostat Service Light

Thermostat service light connection.

24VAC

Thermostat Input

Controls the second stage operation of the unit.

Thermostat Input

Reversing valve solenoid.

Thermostat Input

Controls the operation of the unit.

55, 50, 45, 40

Low Ambient Thermostat Provides selection of the Y2 compressor lock−in temperature. Valid
Pins
options are 40, 45, 50 and 55 degrees Fahrenheit.

DIS−YEL

Coil Sensor

(P4−5) Ground connection for outdoor coil temperature sensor.
(P4−6) Connection for outdoor coil temperature sensor.

AMB−BLACK

Ambient Sensor

(P4−3) Ground connection for outdoor ambient temperature sensor.
(P4−4) Connection for outdoor ambient temperature sensor.

COIL−BROWN

Discharge Sensor

No discharge sensor is used; replaced by 10K resistor.

DELAY

The demand defrost control has a field−selectable function to reduce
occasional sounds that may occur while the unit is cycling in and out of
the defrost mode. When a jumper is installed on the DELAY pins, the
compressor will be cycled off for 30 seconds going in and out of the
defrost mode. Units are shipped with jumper installed on DELAY pins.

Delay Mode

NOTE − The 30 second off cycle is NOT functional when TEST pins on
P1 are jumpered.
P6

TST, PS DF, C, R, O, Y1, Y2

DS1

RED LED

Factory Test Connectors

No field use.

Diagnostic LED

Valid states for demand defrost control two LEDs are OFF, ON and
FLASHING which indicate diagnostics conditions that are described in
table 10.

DS2

GREEN LED

FAN

TWO CONNECTORS

Condenser Fan Operation

These two connections provide power for the condenser fan.

O OUT

24 VAC output

24 VAC output connection for reversing valve.
When the low pressure switch trips, the demand defrost control will cycle
off the compressor, and the strike counter in the demand defrost control
will count one strike. The low pressure switch is ignored under the
following conditions:

LO−PS

Low−Pressure Switch

S
S
S
S

during the defrost cycle and 90 seconds after the termination of
defrost
when the average ambient sensor temperature is below 0°F (−18°C)
for 90 seconds following the start up of the compressor
during TEST mode

Y2 OUT

24 VAC Output

24 VAC output for second stage compressor solenoid.

Y1 OUT

24 VAC Common Output

24 VAC common output, switched for enabling compressor contactor.

HS−PS

High−Pressure Switch

When the high pressure switch trips, the demand defrost control will cycle
off the compressor, and the strike counter in the demand defrost control
will count one strike.

Service Light Output

24VAC service light output.

24V

24 Volt output

24VAC typically used to supply power to the Lennox System Operation
Monitor (LSOM). Not used in this system.

Page 31
XP16 SERIES

DEMAND DEFROST CONTROL (A108) DIAGNOSTIC LEDS
The state (Off, On, Flashing) of two LEDs on the demand defrost control (DS1 [Red] and DS2 [Green]) indicate diagnostics
conditions that are described in table 10.
Table 10. Demand Defrost Control (A108) Diagnostic LEDs
DS1 and DS2 System Status, Fault and Lockout Codes
DS2
Green

DS1
Red

Condition/Code

Possible Cause(s)

Status

Power problem

No power (24V) to demand
defrost control terminals R and C
or demand defrost control failure.

Simultaneous
SLOW Flash

Status

Normal operation

Unit operating normally or in
standby mode.

None required.

Alternating SLOW
Flash

Status

5−minute anti−short cycle delay

Initial power up, safety trip, end of
room thermostat demand.

None required (jumper TEST pins to override)

Simultaneous
FAST Flash

Fault

Ambient Sensor Problem

Sensor being detected open or shorted or out of temperature range. Demand defrost
control will revert to time/temperature defrost operation. (System will still heat or
cool).

Alternating
FAST Flash

Fault

Coil Sensor Problem

Sensor being detected open or shorted or out of temperature range. Demand defrost
control will not perform demand or time/temperature defrost operation. (System will
still heat or cool).

Fault

Demand Defrost Control
Failure

Indicates that demand defrost control has internal component failure. Cycle 24VAC
power to demand defrost control. If code does not clear, replace demand defrost
control.

OFF

SLOW
Flash

Fault

Low Pressure Fault

OFF

Lockout

Low Pressure Lockout

SLOW
Flash

OFF

Fault

High Pressure Fault

OFF

Lockout

High Pressure Lockout

SLOW
Flash

Fault

FAST
Flash

Lockout

OFF

Fast
Flash

Fault

Fast
Flash

OFF

Lockout

OFF

Type

Solution
1
2

Check control transformer power (24V).
If power is available to demand defrost control and LED(s) do not light, replace demand
defrost control.

Restricted air flow over indoor or
outdoor coil.
2 Improper refrigerant charge in
system.
3 Improper
metering device
installed or incorrect operation
of metering device.
4 Incorrect or improper sensor
location or connection to
system.

Remove any blockages or restrictions from
coils and/or fans. Check indoor and outdoor
fan motor for proper current draws.
2 Check system charge using subcooling
method.
3 Check system operating pressures and
compare to unit subcooling tables in this
instruction or located on unit access panel.
4 Make sure all pressure switches and sensors
have secure connections to system to prevent
refrigerant leaks or errors in pressure and
temperature measurements.

Discharge Line Temperature This code detects shorted sensor or high discharge temperatures. If the discharge
Fault
line temperature exceeds a temperature of 285ºF (140ºC) during compressor
operation, the demand defrost control will de−energize the compressor contactor
Discharge Line Temperature
output (and the defrost output if active). The compressor will remain off until the
discharge temperature has dropped below 225ºF (107ºC).
Lockout
Discharge Sensor Fault
Discharge Sensor Lockout

The demand defrost control detects open sensor or out of temperature sensor range.
This fault is detected by allowing the unit to run for 90 seconds before checking
sensor resistance. If the sensor resistance is not within range after 90 seconds, the
demand defrost control will count one fault. After 5 faults, the demand defrost control
will lockout.

(Each fault adds 1 strike to that code’s counter; 5 strikes per code = LOCKOUT)

Page 32

High Pressure Switch (S4)
When the high pressure switch trips, the demand defrost
control will cycle off the compressor, and the strike counter
in the demand defrost control will count one strike. High
Pressure (auto reset) − trip at 590 psig, reset at 418.
Low Pressure Switch (S87)
When the low pressure switch trips, the demand defrost
control will cycle off the compressor, and the strike counter
in the demand defrost control will count one strike. Low
pressure switch (auto reset) − trip at 25 psig, reset at 40
psig.
The low pressure switch is ignored under the following
conditions:
S During the defrost cycle and 90 seconds after the
termination of defrost
S When the average ambient sensor temperature is
below 15° F (−9°C)
S For 90 seconds following the start up of the
compressor
S During test mode
Ambient Sensor (RT13)
The ambient sensor considers outdoor temperatures
below −35°F (−37°C) or above 120°F (48°C) as a fault. If the
ambient sensor is detected as being open, shorted or out
of the temperature range of the sensor, the demand
defrost control will not perform demand defrost operation.
The demand defrost control will revert to time/temperature
defrost operation and will display the appropriate fault
code. Heating and cooling operation will be allowed in this
fault condition.
Coil Sensor (RT21)
Coil SensorThe coil temperature sensor considers
outdoor temperatures below −35°F (−37°C) or above 120°F
(48°C) as a fault. If the coil temperature sensor is detected
as being open, shorted or out of the temperature range of
the sensor, the demand defrost control will not perform
demand or time/temperature defrost operation and will
display the appropriate fault code. Heating and cooling
operation will be allowed in this fault condition.
High Discharge Temperature Sensor (RT28)
If the discharge line temperature exceeds a temperature of
285°F (140°C) during compressor operation, the demand
defrost control will de−energize the compressor contactor
output (and the defrost output, if active). The compressor
will remain off until the discharge temperature has dropped
below 225°F (107°C) and the 5-minute anti−short cycle
delay has been satisfied. This sensor has two fault and
lockout codes:
1. If the demand defrost control recognizes five high
discharge line temperature faults during a single (Y1)
compressor demand, it reverts to a lockout mode and
displays the appropriate code. This code detects
shorted sensor or high discharge temperatures. Code
on demand defrost control is Discharge Line
Temperature Fault and Lockout.

2. If the demand defrost control recognizes five
temperature sensor range faults during a single (Y1)
compressor demand, it reverts to a lockout mode and
displays the appropriate code. The demand defrost
control detects open sensor or out-of-temperature
sensor range. This fault is detected by allowing the unit
to run for 90 seconds before checking sensor
resistance. If the sensor resistance is not within range
after 90 seconds, the demand defrost control will count
one fault. After five faults, the demand defrost control
will lockout. Code on demand defrost control is
Discharge Sensor Fault and Lockout.
The discharge line sensor, which covers a range of 150°F
(65°C) to 350°F (176°C), is designed to mount on a ½"
refrigerant discharge line.
NOTE − Within a single room thermostat demand, if
5−strikes occur, the demand defrost control will lockout the
unit. demand defrost control 24 volt power R must be
cycled OFF or the TEST pins on demand defrost control
must be shorted between 1 to 2 seconds to reset the
demand defrost control.
Crankcase Heater (HR1) and Crankcase Thermostat
Switch (S40)
The reference models are equipped with a 70 watt, belly
band type crankcase heater. HR1 prevents liquid from
accumulating in the compressor. HR1 is controlled by a
thermostat located on the liquid line. When liquid line
temperature drops below 50° F the thermostat closes
energizing HR1. The thermostat will open, de−energizing
HR1 once liquid line temperature reaches 70° F .
Liquid Line Bi−Flow Filter Drier
The unit is equipped with a large−capacity biflow filter drier
which keeps the system clean and dry. If replacement is
necessary, order another of like design and capacity. The
replacement filter drier must be suitable for use with
HFC−410A refrigerant.
The replacement filter drier must be suitable for use with
HFC−410A refrigerant.
SECOND−STAGE OPERATION
If the demand defrost control (A108) receives a call for
second−stage compressor operation Y2 in heating or
cooling mode and the first-stage compressor output is
active, the second-stage compressor solenoid output will
be energized.
If first-stage compressor output is active in heating mode
and the outdoor ambient temperature is below the selected
compressor lock−in temperature, the second-stage
compressor solenoid output will be energized without the
Y2 input. If the jumper is not connected to one of the
temperature selection pins on P3 (40, 45, 50, 55°F), the
default lock−in temperature of 40°F (4.5°C) will be used.
The demand defrost control de−energizes the
second-stage compressor solenoid output immediately
when the Y2 signal is removed or the outdoor ambient
temperature is 5°F above the selected compressor lock−in
temperature, or the first-stage compressor output is
de−energized for any reason.

Page 33
XP16 SERIES

Defrost System
This section addresses:
S Emergency Heat
S Defrost System Overview
S Defrost Control Connections, Jumper Settings and
Features
S Operational Mode Overview (Calibration, Normal and
Defrost)
S Defrost Cycle Actuation
EMERGENCY HEAT (AMBER LIGHT)
An emergency heat function is designed into some room
thermostats. This feature is applicable when isolation of the
outdoor unit is required, or when auxiliary electric heat is
staged by outdoor thermostats. When the room thermostat is
placed in the emergency heat position, the outdoor unit
control circuit is isolated from power and field-provided relays
bypass the outdoor thermostats. An amber indicating light
simultaneously comes on to remind the homeowner that he
is operating in the emergency heat mode.
Emergency heat is usually used during an outdoor unit
shutdown, but it should also be used following a power
outage if power has been off for over an hour and the
outdoor temperature is below 50°F (10°C). System should
be left in the emergency heat mode at least six hours to
allow the crankcase heater sufficient time to prevent
compressor slugging.
DEFROST SYSTEM OVERVIEW
The control monitors ambient temperature, outdoor coil
temperature, and total run time to determine when a
defrost cycle is required. The coil temperature probe is
designed with a spring clip to allow mounting to the outside
coil tubing. The location of the coil sensor is important for
proper defrost operation.
NOTE − The demand defrost control accurately measures
the performance of the system as frost accumulates on the
outdoor coil. This typically will translate into longer running
time between defrost cycles as more frost accumulates on
the outdoor coil before the demand defrost control initiates
defrost cycles.
DEFROST CONTROL CONNECTIONS, JUMPERS
SETTINGS AND FEATURES
Pressure Switch 5−Strike Lockout
The internal control logic of the demand defrost control
counts the pressure switch trips only while the Y1 (Input)
line is active. If a pressure switch opens and closes four
times during a Y1 (Input), the control logic will reset the
pressure switch trip counter to zero at the end of the Y1
(Input). If the pressure switch opens for a fifth time during
the current Y1 (Input), the control will enter a lockout
condition.
The 5−strike pressure switch lockout condition can be reset
by cycling OFF the 24−volt power to the demand defrost
control or by shorting the TEST pins between 1 to 2
seconds. All timer functions (run times) will also be reset.

If a pressure switch opens while the Y1 Out line is
engaged, a 5−minute short cycle will occur after the switch
closes.
Demand Defrost Control Pressure Switch
Connections
The unit’s automatic reset pressure switches (LO PS − S87
and HI PS − S4) are factory−wired into the demand defrost
control on the LO−PS and HI−PS terminals, respectively.
Demand Defrost Control Sensors
Sensors connect to the demand defrost control through a
field-replaceable harness assembly that plugs into the
demand defrost control as illustrated in figure 1. Through
the sensors, the demand defrost control detects outdoor
ambient, coil, and discharge temperature fault conditions.
As the detected temperature changes, the resistance
across the sensor changes.
Testing Demand Defrost Control Sensors
Sensor resistance values can be checked by ohming
across pins shown in table 11.
Table 11. Sensor Temperature /Resistance Range
Pins/W
ire
Color

Sensor

Temperature
Range °F (°C)

Resistance values
range (ohms)

Outdoor

−35 (−37) to 120 (48)

280,000 to 3750

3&4
(Black)

Coil

−35 (−37) to 120 (48)

280,000 to 3750

5&6
(Brown)

Discharge (if
applicable)

24 (−4) to 350 (176)

41,000 to 103

1&2
(Yellow)

Note: Sensor resistance increases as sensed temperature decreases.

Tables 12 and 13 shows how the resistance varies as the
temperature changes for various types of sensors.
NOTE − When checking the ohms across a sensor, be
aware that a sensor showing a resistance value that is not
within the range shown in table 11, may be performing as
designed. However, if a shorted or open circuit is detected,
then the sensor may be faulty and the sensor harness will
need to be replaced.
Defrost Temperature Termination Jumper
Settings (P1)
The demand defrost control selections are: 50, 70, 90, and
100°F (10, 21, 32 and 38°C). The shunt termination pin is
factory set at 50°F (10°C). If temperature shunt is not
installed, default termination temperature is 90°F (32°C).
Test Pins (P1) Function
Placing the jumper on the field test pins (P1) allows the
technician to:
S Clear short cycle lockout
S Clear five−strike fault lockout
S Cycle the unit in and out of defrost mode
S Place the unit in defrost mode to clear the coil
See figure 27 for flowchart of test pin (P1) operations.

Page 34

Compressor Delay Mode (P5)
The demand defrost control has a field−selectable function
to reduce occasional sounds that may occur while the unit
is cycling in and out of the defrost mode. When a jumper is
installed on the DELAY pins, the compressor will be cycled
off for 30 seconds going in and out of the defrost mode.
Units are shipped with jumper installed on DELAY pins.
NOTE − The 30 second off cycle is NOT functional when
jumpering the TEST pins.

1. Frost Detection If the compressor runs longer than
30 minutes and the actual difference between the clear
coil and frosted coil temperatures exceeds the
maximum difference allowed by the demand defrost
control, a defrost cycle will be initiated.
2. Time If six hours of heating mode compressor run
time has elapsed since the last defrost cycle while the
coil temperature remains below 35°F (2°C), the
demand defrost control will initiate a defrost cycle.

OPERATIONAL MODE OVERVIEW
The demand defrost control has three basic operational
modes. Those modes are:
1. Calibration Mode The demand defrost control is
considered uncalibrated when power is applied to the
demand defrost control, after cool mode operation, or
if the coil temperature exceeds the termination
temperature when it is in heat mode (see figure 26 for
further details).
2. Normal Mode The demand defrost control
monitors the O line, to determine the system operating
mode (heat/cool), outdoor ambient temperature, coil
temperature (outdoor coil) and compressor run time to
determine when a defrost cycle is required.
Calibration of the demand defrost control occurs after
a defrost cycle to ensure that there is no ice on the coil.
During calibration, the temperature of both the coil and
the ambient sensor are measured to establish the
temperature differential which is required to allow a
defrost cycle.
3. Defrost Mode The following paragraphs provide a
detailed description of the defrost system operation.

Actuation
When the reversing valve is de−energized, the Y1 circuit is
energized, and the coil temperature is below 35°F (2°C),
the demand defrost control logs the compressor run time.
If the demand defrost control is not calibrated, a defrost
cycle will be initiated after 30 minutes of heating mode
compressor run time. The control will attempt to
self−calibrate after this (and all other) defrost cycle(s).

DEFROST CYCLE ACTUATION
The demand defrost control initiates a defrost cycle based
on either frost detection or time.

Calibration success depends on stable system
temperatures during the 20−minute calibration period. If
the demand defrost control fails to calibrate, another
defrost cycle will be initiated after 45 minutes of heating
mode compressor run time. Once the demand defrost
control is calibrated, it initiates a demand defrost cycle
when the difference between the clear coil and frosted coil
temperatures exceeds the maximum difference allowed
by the control or after six hours of heating mode
compressor run time has been logged since the last
defrost cycle.
Termination
The defrost cycle ends when the coil temperature exceeds
the termination temperature or after 14 minutes of defrost
operation. If the defrost is terminated by the 14−minute
timer, another defrost cycle will be initiated after 30
minutes of run time.

Page 35
XP16 SERIES

DEFROST CONTROL (A108) CALIBRATION MODE SEQUENCE
Occurs after power up and cooling operation, or if the coil temperature exceeds
the termination temperature while in Heat Mode.

Demand defrost control defaults to 30 minute Time / Temperature Mode
Reset Compressor Runtime / Reset Three / Five Strike Counter

DEMAND MODE
Accumulate compressor runtime of
more than 30 minutes while coil
temperature is below 35° F (2°C).
When the accumulated compressor
time exceeds six (6) hours or if the
coil sensor indicates frost is present
on coil, go to Defrost.

THIRTY (30) MINUTE TIME /
TEMPERATURE MODE

45 MINUTE
TIME/TEMPERATURE MODE

Accumulate compressor runtime
while coil temperature is below 35° F
(2°C). When the accumulated
compressor time exceeds 30 minutes
go to Defrost.

Accumulate compressor runtime
while coil temperature is below 35°
F (2°C). When the accumulated
compressor time exceeds 45
minutes go to Defrost.

DEFROST

S
S
S

Outdoor Fan OFF
Reversing Valve ON
W1 line ON

Monitor coil temperature and
time in defrost mode.

HOW DID DEFROST TERMINATE?

Coil temperature was above 35°F (2°C) for four (4)
minutes. of the 14−minute defrost OR reached
defrost termination temperature.

Defrosted for 14−minute without the coil temperature
going above 35°F (2°C) for four (4) minutes and coil
did not reach termination temperature.

DEFROST TERMINATION

S
S
S
S

Compressor runtime counter RESET
Outdoor Fan ON
Reversing Valve OFF
W1 line OFF

Attempt to Calibration Temperature measurements are not taken for the first few minutes of each heat demand. This is
to allow coil temperatures to stabilize. demand defrost control has a maximum of 20 minutes of accumulated compressor
runtime in heat mode to calibrate demand defrost control This may involve more than one heating demand.

YES Calibration occurred

Was stable coil temperature attained
within 20 minutes?

Figure 26. Defrost Calibration

Page 36

NO Demand defrost control
reverts to 45 minute time /
temperature.

Table 12. Ambient (RT13) and Coil (RT21) Sensors Temperature / Resistance Range
Degrees
Fahrenheit
136.3
133.1
130.1
127.3
124.7
122.1
119.7
117.5
115.3
113.2
111.2
109.3
107.4
105.6
103.9
102.3
100.6
99.1
97.6
96.1
94.7
93.3
92.0
90.6
89.4
88.1
86.9
85.7
84.5
83.4
82.3
81.2
80.1
79.0
78.0
77.0
76.0
75.0
74.1
73.1
72.2
71.3
70.4
69.5
68.6
67.7
66.9
66.0
65.2
64.4
63.6
62.8
62.0
61.2
60.5
59.7
59.0
58.2
57.5

Resistance
2680
2859
3040
3223
3407
3592
3779
3968
4159
4351
4544
4740
4937
5136
5336
5539
5743
5949
6157
6367
6578
6792
7007
7225
7444
7666
7890
8115
8343
8573
8806
9040
9277
9516
9757
10001
10247
10496
10747
11000
11256
11515
11776
12040
12306
12575
12847
13122
13400
13681
13964
14251
14540
14833
15129
15428
15730
16036
16345

Degrees
Fahrenheit
56.8
56.0
55.3
54.6
53.9
53.2
52.5
51.9
51.2
50.5
49.9
49.2
48.5
47.9
47.3
46.6
46.0
45.4
44.7
44.1
43.5
42.9
42.3
41.7
41.1
40.5
39.9
39.3
38.7
38.1
37.5
37.0
36.4
35.8
35.2
34.7
34.1
33.5
33.0
32.4
31.9
31.3
30.7
30.2
29.6
29.1
28.6
28.0
27.5
26.9
26.4
25.8
25.3
24.8
24.2
23.7
23.2
22.6
22.1

Resistance
16657
16973
17293
17616
17942
18273
18607
18945
19287
19633
19982
20336
20695
21057
21424
21795
22171
22551
22936
23326
23720
24120
24525
24934
25349
25769
26195
26626
27063
27505
27954
28408
28868
29335
29808
30288
30774
31267
31766
32273
32787
33309
33837
34374
34918
35471
36031
36600
37177
37764
38359
38963
39577
40200
40833
41476
42130
42794
43468

Degrees
Fahrenheit
21.6
21.0
20.5
20.0
19.4
18.9
18.4
17.8
17.3
16.8
16.3
15.7
15.2
14.7
14.1
13.6
13.1
12.5
12.0
11.5
11.0
10.4
9.9
9.3
8.8
8.3
7.7
7.2
6.7
6.1
5.6
5.0
4.5
3.9
3.4
2.8
2.3
1.7
1.2
0.6
0.0
−0.5
−1.1
−1.7
−2.2
−2.8
−3.4
−4.0
−4.6
−5.2
−5.7
−6.3
−6.9
−7.5
−8.2
−8.8
−9.4
−10.0
−10.6

Resistance
44154
44851
45560
46281
47014
47759
48517
49289
50074
50873
51686
52514
53356
54215
55089
55979
56887
57811
58754
59715
60694
61693
62712
63752
64812
65895
67000
68128
69281
70458
71661
72890
74147
75431
76745
78090
79465
80873
82314
83790
85302
86852
88440
90068
91738
93452
95211
97016
98870
100775
102733
104746
106817
108948
111141
113400
115727
118126
120600

Degrees
Fahrenheit
−11.3
−11.9
−12.6
−13.2
−13.9
−14.5
−15.2
−15.9
−16.5
−17.2
−17.9
−18.6
−19.3
−20.1
−20.8
−21.5
−22.3
−23.0
−23.8
−24.6
−25.4
−26.2
−27.0
−27.8
−28.7
−29.5
−30.4
−31.3
−32.2
−33.2
−34.1
−35.1
−36.1
−37.1
−38.2
−39.2

Resistance
123152
125787
128508
131320
134227
137234
140347
143571
146913
150378
153974
157708
161588
165624
169824
174200
178762
183522
188493
193691
199130
204829
210805
217080
223677
230621
237941
245667
253834
262482
271655
281400
291774
302840
314669
327343

Page 37
XP16 SERIES

Table 13. High Discharge Sensor (RT28) Temperature / Resistance Range
Degrees
Fahrenheit
303.1
298.1
293.4
289.0
284.8
280.9
277.1
273.6
270.2
267.0
263.9
260.9
258.1
255.3
252.7
250.1
247.7
245.3
243.0
240.8
238.6
236.5
234.4
232.4
230.5
228.6
226.7
224.9
223.2
221.5
219.8
218.1
216.5
214.9
213.4
211.9
210.4
208.9
207.5
206.0
204.6
203.3
201.9
200.6
199.3
198.0
196.8
195.5
194.3
193.1
191.9
190.7
189.5
188.4
187.2

Resistance
183
195
207
220
232
245
258
270
283
297
310
323
336
350
364
378
391
405
420
434
448
463
478
492
507
523
538
553
569
584
600
616
632
649
665
682
698
715
732
750
767
785
803
821
839
857
876
894
913
932
952
971
991
1011
1031

Degrees
Fahrenheit
186.1
185.0
183.9
182.8
181.8
180.7
179.6
178.6
177.6
176.6
175.5
174.6
173.6
172.6
171.6
170.6
169.7
168.7
167.8
166.9
165.9
165.0
164.1
163.2
162.3
161.4
160.5
159.7
158.8
157.9
157.1
156.2
155.3
154.5
153.6
152.8
152.0
151.1
150.3
149.5
148.7
147.9
147.1
146.2
145.4
144.6
143.8
143.0
142.3
141.5
140.7
139.9
139.1
138.3
137.6

Resistance
1052
1072
1093
1114
1135
1157
1179
1201
1223
1245
1268
1291
1315
1338
1362
1386
1411
1435
1460
1486
1511
1537
1563
1590
1617
1644
1672
1699
1728
1756
1785
1815
1845
1875
1905
1936
1968
1999
2032
2064
2098
2131
2165
2200
2235
2270
2306
2343
2380
2418
2456
2495
2534
2574
2615

Degrees
Fahrenheit
136.8
136.0
135.2
134.5
133.7
132.9
132.2
131.4
130.6
129.9
129.1
128.4
127.6
126.8
126.1
125.3
124.6
123.8
123.1
122.3
121.6
120.8
120.1
119.3
118.5
117.8
117.0
116.3
115.5
114.8
114.0
113.2
112.5
111.7
111.0
110.2
109.4
108.7
107.9
107.1
106.4
105.6
104.8
104.0
103.3
102.5
101.7
100.9
100.1
99.3
98.5
97.7
96.9
96.1
95.3

Page 38

Resistance
2656
2698
2740
2783
2827
2872
2917
2963
3010
3057
3105
3154
3204
3255
3307
3359
3413
3467
3523
3579
3637
3695
3755
3816
3877
3940
4005
4070
4137
4205
4274
4345
4418
4491
4567
4644
4722
4802
4884
4968
5054
5141
5231
5323
5416
5512
5610
5711
5814
5920
6028
6139
6253
6370
6489

Degrees
Fahrenheit
94.5
93.6
92.8
92.0
91.2
90.3
89.5
88.6
87.8
86.9
86.0
85.2
84.3
83.4
82.5
81.6
80.7
79.8
78.8
77.9
76.9
76.0
75.0
74.1
73.1
72.1
71.1
70.0
69.0
68.0
66.9
65.8
64.7
63.6
62.5
61.3
60.2
59.0
57.8
56.6
55.3
54.0
52.7
51.4
50.0
48.6
47.2
45.7

Resistance
6613
6739
6869
7002
7139
7281
7426
7575
7729
7888
8051
8220
8394
8574
8759
8951
9149
9354
9566
9786
10013
10250
10495
10749
11014
11289
11575
11873
12184
12509
12848
13202
13573
13961
14368
14796
15246
15719
16218
16744
17301
17891
18516
19180
19887
20641
21448
22311

TEST

Placing the jumper on the field test pins (P1) allows the technician to:

S
S
S
S

Clear short cycle lockout
Clear five−strike fault lockout
Cycle the unit in and out of defrost mode
Place the unit in defrost mode to clear the coil

When Y1 is energized and 24V power is being applied to the Control, a test cycle can be initiated by placing a jumper on the Control’s TEST pins for 2 to
5 seconds. If the jumper remains on the TEST pins for longer than five seconds, the Control will ignore the jumpered TEST pins and revert to normal
operation.
The Control will initiate one test event each time a jumper is placed on the TEST pins. For each TEST the jumper must be removed for at least one
second and then reapplied.
Y1 Active

Place a jumper on TEST pins for
longer than one second but less
than two seconds.

Clears any short cycle lockout and
five strike fault lockout function, if
applicable. No other functions will be
executed and unit will continue in the
mode it was operating.

Place a jumper on TEST pins for
more than two seconds.

Clears any short cycle lockout and
five strike fault lockout function, if
applicable.

ACTIVE

INACTIVE

O Line Status

If in COOLING Mode

If in DEFROST Mode

If in HEATING Mode

No further test mode operation will be
executed until the jumper is removed
from the TEST pins and reapplied.

The unit will terminate defrost and
enter HEAT MODE uncalibrated
with defrost timer set for 45 minute
test.

If no ambient or coil sensor fault
exist, unit will go into DEFROST
MODE.
If ambient or coil faults exist (open or
shorted), unit will remain in HEAT
MODE.

NOTE Placing a jumper on the TEST pins will not bring the unit
out of inactive mode. The only way manually activate the heat
pump from an inactive mode is to cycle the 24VAC power to the
Control.

If jumper on TEST pins remains in
place for more than five seconds.

If jumper on TEST pins is removed
before a maximum of five seconds.

The unit will return to HEAT MODE
un−calibrated with defrost timer set
for 34 minutes.

The unit will remain in DEFROST
MODE until termination on time or
temperature.

Figure 27. Test Pin (P1) Functions
Page 39
XP16 SERIES

12. After testing is complete, return unit to original set up.

Two−Stage Modulation Compressors
Checks

Maintenance

Use this checklist on page 42 to verify part-load and
full-load capacity operation of two-stage modulation
compressors.
TOOLS REQUIRED
S Refrigeration gauge set
S Digital volt/amp meter
S Electronic temperature thermometer
S On-off toggle switch

DEALER
Maintenance and service must be performed by a qualified
installer or service agency. At the beginning of each
cooling season, the system should be checked as follows:
Outdoor Unit
1. Clean and inspect outdoor coil (may be flushed with a
water hose). Ensure power is off before cleaning.
2. Outdoor unit fan motor is pre−lubricated and sealed.
No further lubrication is needed.
3. Visually inspect all connecting lines, joints and coils for
evidence of oil leaks.
4. Check all wiring for loose connections.
5. Check for correct voltage at unit (unit operating).
6. Check amp draw on outdoor fan motor.
Motor Nameplate:_________ Actual:__________.

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 proper to
correctly perform compressor modulation 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).
PROCEDURE
NOTE − Block outdoor coil to maintain a minimum of 375
psig during testing).
1. Turn main power OFF to outdoor unit.
2. Adjust room thermostat set point 5ºF above 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.

7. Inspect drain holes in coil compartment base and
clean if necessary.
NOTE - If insufficient heating or cooling occurs, the unit
should be gauged and refrigerant charge should be
checked.
Outdoor Coil
It may be necessary to flush the outdoor coil more
frequently if it is exposed to substances which are
corrosive or which block airflow across the coil (e.g., pet
urine, cottonwood seeds, fertilizers, fluids that may contain
high levels of corrosive chemicals such as salts)

S
S

4. Turn toggle switch OFF and install switch in series with
Y2 wire from room thermostat.
5. Cycle main power ON.
6. Allow pressures and temperatures to stabilize before
taking measurements (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.
9. Allow pressures and temperatures to stabilize before
taking measurements (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 Two−Stage Modulation Compressor Field
Operational Checklist on page 42, 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 modulating between low and high capacity and
replacement is necessary).

Page 40

Outdoor Coil The outdoor coil may be flushed with
a water hose.
Outdoor Coil (Sea Coast) Moist air in ocean
locations can carry salt, which is corrosive to most
metal. Units that are located near the ocean require
frequent inspections and maintenance. These
inspections will determine the necessary need to wash
the unit including the outdoor coil. Consult your
installing contractor for proper intervals/procedures
for your geographic area or service contract.
Indoor Unit
1. Clean or change filters.
2. Lennox blower motors are prelubricated and
permanently sealed. No more lubrication is needed.
3. Adjust blower speed for cooling. Measure the pressure
drop over the coil to determine the correct blower CFM.
Refer to the unit information service manual for pressure
drop tables and procedure.
4. Belt Drive Blowers − Check belt for wear and proper
tension.
5. Check all wiring for loose connections.
6. Check for correct voltage at unit. (blower operating)
7. Check amp draw on blower motor.
Motor Nameplate:_________ Actual:__________.

Indoor Coil
1. Clean coil if necessary.
2. Check connecting lines, joints and coil for evidence of
oil leaks.
3. Check condensate line and clean if necessary.

HOMEOWNER
Cleaning of the outdoor unit’s coil should be performed by
a trained service technician. 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 and diminish performance and longevity
of the unit.
Outdoor Coil
The outdoor unit must be properly maintained to ensure its
proper operation.

Please contact your dealer to schedule proper
inspection 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
periodically check for debris which collects around the
unit.
Cleaning of the outdoor unit’s coil should be performed by
a trained service technician. 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.
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.
1. Air Filter 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 Filter Disposable filters should be
replaced with a filter of the same type and size.
NOTE If you are unsure about the filter required for your
system, call your Lennox dealer for assistance.
3. Reusable Filter Many indoor units are equipped
with reusable foam filters. Clean foam filters with a
mild soap and water solution; rinse thoroughly; allow

filter to dry completely before returning it to the unit or
grille.
NOTE The filter and all access panels must be in place
any time the unit is in operation.
4. Indoor Unit The indoor unit’s 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 thermostat homeowner manual for instructions on
how to operate your thermostat.
Heat Pump Operation
Your new Lennox heat pump has several characteristics
that you should be aware of:
S Heat pumps satisfy heating demand by delivering
large amounts of warm air into the living space. This
is quite different from gas- or oil-fired furnaces or an
electric furnace which deliver lower volumes of
considerably hotter air to heat the space.
S Do not be alarmed if you notice frost on the outdoor coil
in the winter months. Frost develops on the outdoor
coil during the heating cycle when temperatures are
below 45F (7C). An electronic control activates a
defrost cycle lasting 5 to 15 minutes at preset intervals
to clear the outdoor coil of the frost.
S During the defrost cycle, you may notice steam rising
from the outdoor unit. This is a normal occurrence. The
thermostat may engage auxiliary heat during the
defrost cycle to satisfy a heating demand; however,
the unit will return to normal operation at the
conclusion of the defrost cycle.
Extended Power Outage
The heat pump is equipped with a compressor crankcase
heater which protects the compressor from refrigerant
slugging during cold weather operation.
If power to your unit has been interrupted for several hours
or more, set the room thermostat selector to the
EMERGENCY HEAT setting to obtain temporary heat
without the risk of serious damage to the heat pump.
In EMERGENCY HEAT mode, all heating demand is
satisfied by auxiliary heat; heat pump operation is locked
out. After a six-hour compressor crankcase warm-up
period, the thermostat can be switched to the HEAT setting
and normal heat pump operation may resume.
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 41
XP16 SERIES

Accessories
For update−to−date information, see any of the following
publications:

S
S
S

Lennox XP16 Engineering Handbook
Lennox Product Catalog
Lennox Price Book

Checklists
Two−Stage Modulation Compressors Field Operational Checklist

Unit Readings

Y1 − First-Stage

Expected results during Y2 demand
(Toggle switch On)

COMPRESSOR

Voltage

Same

Amperage

Higher

OUTDOOR UNIT FAN MOTOR

Amperage

Same or Higher

TEMPERATURE

Ambient

Same

Outdoor Coil Discharge Air

Higher

Compressor Discharge Line

Higher

Indoor Return Air

Same

Indoor Coil Discharge Air

Lower

PRESSURES

Suction (Vapor)

Lower

Liquid

Higher

Page 42

Y2 − Second-Stage

XP16 Start−Up and Performance
Customer

Address

Indoor Unit Model

Serial

Outdoor Unit Model

Serial

Notes:

START UP CHECKS
Refrigerant Type:
1st Stage: Rated Load Amps

Actual Amps

Rated Volts

Actual Volts

2nd Stage: Rated Load Amps

Actual Amps

Rated Volts

Actual Volts

Outdoor Unit Fan Full Load Amps

Actual Amps:

1st Stage

2nd Stage

COOLING MODE
Suction Pressure: 1st Stage:

2nd Stage:

Liquid Pressure: 1st Stage:

2nd Stage:

Supply Air Temperature: 1st Stage:

2nd Stage:

Temperature: Ambient:

Return Air:

System Refrigerant Charge (Refer to manufacturer’s information on unit or installation instructions for required subcooling and approach temperatures.)
A

Subcooling:

Saturated Condensing Temperature (A) minus Liquid
Line Temperature (B)
A

Approach:

Indoor Coil Temperature Drop (18 to 22°F)

Liquid Line Temperature (A) minus Outdoor Air
Temperature (B)
A

APPROACH
=

Return Air Temperature (A) minus Supply Air
Temperature (B)

SUBCOOLING

COIL TEMP DROP
=

Page 43
XP16 SERIES

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