Lennox SL18XC1, XP21-036, XP21-060, XP21-024, XP21-048 Installation Instructions Manual

INSTALLATION

E2016 Lennox Industries Inc.

Dallas, Texas, USA

THIS MANUAL MUST BE LEFT WITH THE

HOMEOWNER FOR FUTURE REFERENCE

General

This SL18XC1 outdoor air conditioner with all-aluminum
coil is designed for use with HFC-410A refrigerant only.

This unit must be installed with an approved indoor air han
dler or coil. See the Lennox SL18XC1 Product Specifica
tions bulletin (EHB) for approved indoor component match
ups.

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.

NOTICE !

For more in-depth information, consult the Installa
tion and Service Procedures manual, available as
Corp. 1405-L10 on DaveNet or through the Technical
Support department at 800-453-6669.

INSTRUCTIONS

Dave Lennox Signature
Collection SL18XC1 System

AIR CONDITIONERS
507353-01
7/2018

WARNING

Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal inju
ry or loss of life.

Installation and service must be performed by a licensed
professional installer (or equivalent) or service agency.

CAUTION

Before attempting to perform any service or mainte
nance, turn the electrical power to unit OFF at discon
nect switch.

®

STEP 1 -- SETTING THE UNIT -- Clearances

CLEARANCE ON ALL SIDES — INCHES (MILLIMETERS)

6 (152)

CONTROL

PANEL ACCESS

LOCATION

24

(610)

30 (762)

12 (305)

36 (914)

MINIMUM CLEARANCE BETWEEN TWO UNITS

NOTES:

S Clearance to access panel must be 30

inches (762mm).

S Clearance to one of the other three

sides must be 36 inches (914mm).

S Clearance to one of the remaining two

sides may be 12 inches (305mm) and
the final side may be 6 inches
(152mm).

ACCESS PANEL

LINE SET

CONNECTIONS

MINIMUM CLEARANCE

ABOVE UNIT

48 (1219)

REAR VIEW OF UNIT

FIGURE 1

Page 1

STEP 1 -- SETTING THE UNIT (Continued) -- Dimensions / Placement

UNIT DIMENSIONS - INCHES (MM)

39.40”
(1003)

DISCHARGE AIR

ELECTRICAL INLETS

[-030 THROUGH -042]

SUCTION LINE
INLET

LIQUID
LINE
INLET

41 (1040)

[-024, -048, -060]

47 (1194)

18.60”
(470)

8.00” (203)

35.50”
(902)

SIDE VIEW

UNIT SUPPORT

FEET

3-1/8

16-7/8

(429)

8-3/4
(222)

(79)

WARNING

To prevent personal injury, as well as damage to panels,
unit or structure, observe the following:

While installing or servicing this unit, carefully stow all
removed panels so that the panels will not cause injury
to personnel, objects or nearby structures. Also, take
care to store panels where they will not be subject to
damage (e.g., being bent or scratched).

While handling or stowing the panels, consider any
weather conditions (especially wind) that may cause
panels to be blown around and damaged.

CAUTION

As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and use protective
clothing.

30-3/4

(781)

1 (25)

26-7/8

(683)

3-3/4 (95)

4-5/8
(117)

ACCESS VIEW

BASE WITH
ELONGATED LEGS

NOTICE !

Roof Damage!
This system contains both refrigerant and oil. Some

rubber roofing material may absorb oil, causing the
rubber to degrade. Failure to follow this notice
could result in damage to roof surface.

IMPORTANT !

Exhaust vents from dryers, water heaters and
furnaces should be directed away from the outdoor
unit. Prolonged exposure to exhaust gases and the
chemicals contained within them may cause
condensation to form on the steel cabinet and other
metal components of the outdoor unit. This will
diminish unit performance and longevity.

Page 2

PLACEMENT

INSTALL UNIT AWAY

FROM WINDOWS

TWO 90_ ELBOWS INSTALLED IN LINE SET

WILL REDUCE LINE SET VIBRATION

FIGURE 2

SLAB MOUNTING

Install unit level or, if on a slope, maintain slope tolerance of 2
degrees (or 2 inches per 5 feet [50 mm per 1.5 m]) away from
building structure.

BUILDING

STRUCTURE

DISCHARGE AIR

STABILIZING UNIT ON UNEVEN SURFACES

Slab Mounting

#10 X 1/2” LONG

SELF-DRILLING

SHEET METAL

SCREWS

STABILIZING BRACKET

(18 GAUGE METAL — 2”

WIDTH; HEIGHT AS

REQUIRED)

#10 X 1-1/4” LONG

HEX HD SCREW AND

FLAT WASHER

Concrete slab — use two
plastic anchors (hole drill 1/4”)

CORNER POST

Deck Top Mounting

Stabilizing bracket - 18 gauge metal.
2” (50.8mm) width; height as required.
Bent to form right angle as shown.

SAME FASTENERS AS
SLAB SIDE MOUNTING.

COIL

BASE PAN

MOUNTING
SLAB

GROUND LEVEL

FIGURE 3

ELEVATED SLAB MOUNTING USING FEET

EXTENDERS

2” (50.8MM) SCH 40

FEMALE THREADED

ADAPTER

2” (50.8MM)
SCH 40 MALE
THREADED
ADAPTER

LEG DETAIL

Use additional 2” SCH 40 male
threaded adapters which can
be threaded into the female
threaded adapters to make
additional adjustments to the
level of the unit.

BASE

FIGURE 4

MINIMUM ONE

PER SIDE

FOR EXTRA

STABILITY

Install one bracket per side (minimum). For extra stability, install
two brackets per side, two inches (51mm) from each corner.

IMPORTANT !

Unit Stabilizer Bracket (field-provided):

Always use stabilizers when unit is raised above
the factory height.
(Elevated units could become unstable in gusty
wind conditions.)

Stabilizers may be used on any unit installed on
unstable and uneven surfaces.

FIGURE 5

STEP 2 -- ELECTRICAL -- Circuit Sizing
and Wire Routing

In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).

Refer to the furnace or air handler installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.

Page 3

SL18XC1 SERIES

24VAC TRANSFORMER

Use the transformer provided with the furnace or air han
dler for low‐voltage control power (24VAC - 40 VA mini
mum).

WARNING

Electric Shock Hazard. Can cause injury
or death. Unit must be grounded in
accordance with national and local
codes.

Line voltage is present at all components
when unit is not in operation on units with
single‐pole contactors. Disconnect all
remote electric power supplies before
opening access panel. Unit may have
multiple power supplies.

IMPORTANT !

If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start-up to pre
vent compressor damage as a result of slugging.

1. Size Circuit and Install Disconnect: Refer to unit

nameplate for minimum circuit ampacity, and maximum
fuse or circuit breaker size (HACR per NEC). Install pow

er wiring and properly sized disconnect switch.

NOTE — Units are approved for use only with cop
per conductors. Ground unit at disconnect switch or
connect to an earth ground.

2. Install Thermostat: Install room thermostat (ordered

separately) on an inside wall in the center of the condi
tioned area and 5 feet (1.5m) from the floor. The ther
mostat should not be installed on an outside wall or
where it can be affected by sunlight or drafts.

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

CAUTION

Electrostatic discharge can affect
electronic components. Take care
during unit installation and service to
protect the unit's electronic controls.

ELECTROSTATIC

DISCHARGE

(ESD)

Precautions and

Procedures

Precautions will help to avoid control
exposure to electrostatic discharge by
putting the unit, the control and the
technician at the same electrostatic
potential. Touch hand and all tools on an
unpainted unit surface before
performing any service procedure to
neutralize electrostatic charge.

A. ROUTE CONTROL WIRES — NON-COMMUNICATING

Install low voltage control wiring from outdoor to indoor unit and from
thermostat to indoor unit. All low voltage wiring must enter unit through
provided field-installed busing installed in electrical inlet.

Run 24VAC control wires through hole with grommet.
Make 24VAC control wire connections to heat pump control (A175).

NOTE — Do not bundle any excess 24VAC control wires inside control box.
NOTE — Wire tie provides low voltage wire strain relief and maintains

separation of field-installed low and high voltage circuits.
NOTE — For proper voltages, select control wires gauge per table below.

WIRE RUN LENGTH AWG# INSULATION TYPE

LESS THAN 100' (30 METERS) 18 TEMPERATURE RATING

MORE THAN 100' (30 METERS) 16 35ºC MINIMUM.

B

A

HOLE

CONTROL
(A175)

B. ROUTE CONTROL WIRES — COMMUNICATING

Maximum length of wiring (18 gauge) for all connections on the RSBus is 1500 feet (457 meters). Wires should be color-coded, with a temperature rating
of 95ºF (35ºC) minimum, and solid-core (Class II Rated Wiring). All low voltage wiring must enter unit through provided field-installed busing installed
in electrical inlet.

Communicating systems using the iComfortt-enabled thermostat require four thermostat wires between the thermostat and the furnace/air handler
control and four wires between the outdoor unit and the furnace/air handler control. When a thermostat cable with more than four wires is used, the extra
wires must be properly connected to avoid electrical noise (see illustration below).

Use a wire nut to bundle the four unused wires at each end of the cable. Each bundle should also include an additional wire that should be connected
on each end to the C terminal as shown in figure 7.

iComfortt-enabled

Outdoor Unit

Single Wire To

C Terminal

iComfortt-enabled

Indoor Unit

Single Wire To
C Terminal

iComfortt-enabled

thermostat

Unused Wires

Unused Wires

FIGURE 6

Page 4

B. ROUTE HIGH VOLTAGE AND GROUND WIRES

Any excess high voltage field wiring should be trimmed and secured away from any low voltage field wiring. To facilitate a conduit, a
cutout is located in the bottom of the control box. Connect conduit to the control box using a proper conduit fitting.

WATERTIGHT

CONDUIT FITTING

GROUND LUG*

CONTROL BOX

ACCESS VIEW

* Attach field-provided

WATERTIGHT

FLEXIBLE CONDUIT

CONTACTOR

ELECTRICAL

INLET (HIGH

VOLTAGE)

WIRING ENTRY

POINTS

green ground wire to
provided ground lug.

NOTE - Grounding wire
must be a single, contin
uous wire run from unit
ground lug to earth
ground. DO NOT splice

TO SERVICE

DISCONNECT BOX

ELECTRICAL INLET (CONTROL WIRING —
LOW VOLTAGE). USE BUSHING
PROVIDED IN BAG ASSEMBLY HERE.

wire.

FIGURE 7

STEP 2 -- ELECTRICAL (Continued) -- Outdoor Control (A175) Jumpers and Terminals

J4 - COMPRESSOR

SHIFT DELAY

30

SECOND DELAY

(DEFAULT)

0

SECOND DELAY

30

J2 - SECOND-STAGE

LOCK-IN

TEMPERATURE

(TWO-STAGE HEAT PUMP ONLY)

55

DEGREE
TARGET

50
DEGREE
TARGET

45
DEGREE
TARGET

40
DEGREE

TARGET (DEFAULT)

55

50

45

55

50

45

55

50

45

55

50

45

40

7-SEGMENT DISPLAY

PUSH BUTTON

J3 - DEFROST AUTO

(HEAT PUMP ONLY)

JUMPER ON PINS 1 AND 2

DEFROST AUTO ENABLED

JUMPER ON PINS 2 AND 3

DEFROST AUTO DISABLED (DEFAULT)

ON

OFF

J1 - DEFROST TERMINATION

0

SECOND-STAGE LOCK-IN

40

40

TEMPERATURE

TEMPERATURE

MAX

TARGET

90

MAX

90

DEGREE

TARGET

90

70

DEGREE

TARGET

MAX

MAX

DS TO R LINK - EDA

(HEAT PUMP ONLY)

70

50

(DEFAULT WHEN JUMPER IS

REMOVED OR MISSING)

70

50

70
DEGREE
TARGET

(DEFAULT)

90

70

50

MAX

90

90

70

50

MAX

90

70

50

APPLICATION

(TWO-STAGE UNIT ONLY)

40

NOTE - LINK NOT APPLICABLE TO SINGLE-STAGE
UNIT. CUTTING LINK WILL HAVE NO AFFECT ON
OPERATION OF SINGLE-STAGE UNITS

.

CUT FOR HUMIDITROL® - ENHANCED
DEHUMIFICATION ACCESSORY (EDA)
APPLICATIONS.

FIGURE 8

Page 5

SL18XC1 SERIES

STEP 2 -- ELECTRICAL (Continued) -- Field Control Wiring

The following two illustrations provide examples of control wiring connections when using a non-communicating thermostat.
For examples of control wiring in complete or partial communicating systems, see the iComfortt-enabled thermostat
Quick Start Guide which is provided with the thermostat.

On−board link

Low voltage thermostat wiring

Flat metal jumper

1. Thermostat T terminals are used for outdoor

sensor input. Use for thermostat's outdoor
temperature display (optional).

2. R to L connection is required for this model only

when used with the ComfortSense
thermostat- (catalog number Y0349). Resistor Kit
(catalog number 47W97) required and ordered
separately.

3. Air handler control ships from factory with metal

jumpers (links) installed across W1, W2 and W3.
For single-stage electric heat, do not remove
factory-installed metal link.

4. Air handler control ships from factory with metal

jumpers installed across W1, W2 and W3. For
two-stage electric heat, cut factory-installed metal
link between W1 and W2. Then, connect
thermostat wire between the air handler control's
W2 and the thermostat's W2 terminal.

5. Cut on-board link (clippable wire) DS-R for

Humiditrol
slow the indoor blower motor to the lowest speed
setting. See air handler installation instruction or
product specifications bulletin for lowest fan speed
information.

®

or Harmony IIIt applications. This will

®

7000

Single−Stage

Air Conditioner Control

W
L

Y2
Y1

O

DS

2

C

i−

i+

R

FIGURE 9

Air Handler Control

DS

O

5

L
H

DH

R

C

Y1
Y2

G

W3
W2

3

W1

ComfortSense[ 7000 Thermostats

Catalog # Y0349 or Y2081

R

G

W2
W1

O
L

H
D

B

Y2
Y1

1

C

4

T
T

On−board link

Low voltage thermostat wiring

Flat metal jumper

1. Thermostat T terminals are used for outdoor sen

sor input. Sensor provides input for thermostat's
outdoor temperature display (optional).

2. R to L connection is required for this model only

when used with the ComfortSense
mostat - (catalog number Y0349). Resistor Kit
(catalog number 47W97) is required and must be
ordered separately.

3. Cut on-board link (clippable wire) DS-R for Humi

®

ditrol

or Harmony IIIt applications. This will slow
the indoor blower motor to the lowest speed set
ting. See furnace installation instruction or prod
uct specification bulletin for lowest fan speed in
formation.

®

7000 ther

Single−Stage

Air Conditioner Control

W

L

Y2
Y1

O

DS

2

C

i−

i+

R

Furnace Control

DS

O
L

3

H

DH

R

C

Y1
Y2

G

W2
W1

ComfortSense[ 7000 Thermostats

Catalog # Y0349 or Y2081

R

G

W2
W1

O
L

H
D

B

Y2
Y1

1

C

T
T

Cut on-board link (W914) (clippable wire) from DS to R for dehumidification (Optional).

FIGURE 10

Page 6

STEP 3 -- REFRIGERANT PIPING —
Flushing Existing Line Set & Indoor Coil

Flush the existing line set per the following instruc

tions. For more information, refer to the Installation
and Service Procedures manual available on Dav
eNet. CAUTION - DO NOT attempt to flush and re-use
existing line sets or indoor coil when the system con
tains contaminants (i.e., compressor burn out).

NOTE - When installing refrigerant lines longer than 50
feet, refer to the Refrigerant Piping Design and Fabrication
Guidelines manual available on DaveNet (Corp. 9351-L9),
or contact the Technical Support Department Product Ap
plication group for assistance.

NOTE - For new or replacement line set installation, refer
to Service and Application Note - Corp. 9112-L4 (C-91-4).

TABLE 1

REFRIGERANT LINE SET — INCHES (MM)

Field

Model

Size

-024

-030

-036

-042

-048

-060

NOTE — Some applications may require a field-provided 7/8” to
1-1/8” adapter

Connections

Liquid

Line

3/8“

(10)

3/8“

(10)

3/8“

(10)

3/8“

(10)

Suction

Line

3/4“
(19)

7/8“
(22)

7/8“
(22)

1-1/8“.

(29)

Recommended Line Set

Liquid

Line

3/8“
(10)

3/8“
(10)

3/8“
(10)

3/8“
(10)

Suction

Line

3/4“
(19)

7/8“
(22)

7/8“
(22)

1-1/8“

(29)

L15

Line Sets

Feet (Meters)

L15-41

15 - 50' (5 - 15)

L15-65

15 - 50' (5 - 15)

Field Fabricated

IMPORTANT !

If this unit is being matched with an approved line
set or indoor unit coil that was previously charged
with mineral oil, or if it is being matched with a coil
which was manufactured before January of 1999,
the coil and line set must be flushed prior to installa
tion. Take care to empty all existing traps. Polyol es
ter (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 sys
tem performance and capacity.

Failure to properly flush the system per this instruc
tion and the detailed Installation and Service Proce
dures manual will void the warranty.

WARNING

When using a high pressure gas such as
nitrogen to pressurize a refrigeration or air
conditioning system, use a regulator that
can control the pressure down to 1 or 2
psig (6.9 to 13.8 kPa).

WARNING

Refrigerant can be harmful if it is inhaled. Refrigerant
must be used and recovered responsibly.

Failure to follow this warning may result in personal injury
or death.

WARNING

Fire, Explosion and Personal Safety Haz
ard. Failure to follow this warning could re
sult in damage, personal injury or death.

Never use oxygen to pressurize or purge
refrigeration lines. Oxygen, when exposed
to a spark or open flame, can cause fire
and/or an explosion, that could result in
property damage, personal injury or death.

WARNING

Polyol ester (POE) oils used with HFC-410A
refrigerant absorb moisture very quickly. It is very
important that the refrigerant system be kept closed
as much as possible. DO NOT remove line set caps
or service valve stub caps until you are ready to make
connections.

IMPORTANT !

Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction pres
sure 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 COM
PRESSOR.

Page 7

SL18XC1 SERIES

STEP 4 -- REFRIGERANT PIPING -- Removing Existing Indoor Metering Device

TYPICAL EXISTING FIXED ORIFICE

1A

DISTRIBUTOR

ASSEMBLY

1. On fully cased coils, remove the coil access and plumbing panels.

2. Remove any shipping clamps from the liquid line and distributor as
sembly.

3. Using two wrenches, disconnect liquid line from liquid line orifice hous
ing. Take care not to twist or damage distributor tubes during this pro
cess.

4. Remove and discard fixed orifice, valve stem assembly (if present)
and Teflon® washer as illustrated above.

5. Use a field-provided fitting to temporarily reconnect the liquid line to the
indoor unit's liquid line orifice housing.

(UNCASED COIL SHOWN)

DISTRIBUTOR TUBES

LIQUID LINE ORIFICE HOUSING

TEFLON® RING

FIXED ORIFICE

REMOVE AND DISCARD

WHITE TEFLON

(IF PRESENT)

®

SEAL

LIQUID LINE ASSEMBLY

(INCLUDES STRAINER)

REMOVAL PROCEDURE

OR

BRASS NUT

1B

TWO-PIECE PATCH PLATE

CONNECT GAUGES AND EQUIPMENT FOR
FLUSHING PROCEDURE

2

CYLINDER CONTAINING
CLEAN HCFC-22* TO BE
USED FOR FLUSHING
(Positioned to deliver liquid

A

refrigerant)

1

VAPOR LINE

SERVICE VALVE

EXISTING

INDOOR

UNIT

LIQUID LINE SERVICE

VALV E

RECOVERY

CYLINDER

VAPOR

LIQUID

OUTDOOR

B

NEW

UNIT

OPENED

C

D

RECOVERY MACHINE

A. HCFC-22 cylinder with clean refrigerant* (positioned to deliver liquid

refrigerant) to the vapor service valve.

B. HCFC-22 gauge set (low side) to the liquid line valve.
C. HCFC-22 gauge set center port to inlet on the recovery machine with an

empty recovery tank connected to the gauge set.

D. Connect recovery tank to recovery machine per machine instructions.

GAUGE

MANIFOLD

LOW HIGH

CLOSED

TANK
RETURN

INLET

DISCHARGE

TYPICAL EXISTING EXPANSION VALVE REMOVAL
PROCEDURE (UNCASED COIL SHOWN)

ORIFICE

HOUSING

EQUALIZER
LINE

STUB END

TEFLON
RING

VAPOR

EXPANSION

VALV E

®

LIQUID LINE

ASSEMBLY WITH

BRASS NUT

LINE

TEFLON

(UNCASED COIL ONLY)

DISTRIBUTOR

TUBES

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER

LINE FITTING

1. On fully cased coils, remove the coil access and plumbing panels.

2. Remove any shipping clamps from the liquid line and distributor
assembly.

3. Disconnect the equalizer line from the expansion valve equalizer
line fitting on the vapor line.

4. Remove the vapor line sensing bulb.

5. Disconnect the liquid line from the expansion valve at the liquid line
assembly.

6. Disconnect the expansion valve from the liquid line orifice housing.
Take care not to twist or damage distributor tubes during this
process.

7. Remove and discard expansion valve and the two Teflon® rings.

8. Use a field-provided fitting to temporarily reconnect the liquid line to
the indoor unit's liquid line orifice housing.

LIQUID LINE

SENSING BULB

FLUSHING LINE SET

The line set and indoor unit coil must be flushed with at least the same

3

amount of clean refrigerant* that previously charged the system.
Check the charge in the flushing cylinder before proceeding.

1. Set the recovery machine for liquid recovery and start the recovery
machine. Open the gauge set valves to allow the recovery
machine to pull a vacuum on the existing system line set and indoor
unit coil.

B

2. Position the cylinder of clean HCFC-22* for delivery of liquid
refrigerant 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.

3. 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 the system
down to 0.

4. Close the valve on the inverted HCFC-22 cylinder and the gauge
set valves. Pump the remaining refrigerant out of the recovery
machine and turn the machine off.

RING

®

SENSING

LINE

LIQUID

LINE

*IMPORTANT - Clean refrigerant is any refrigerant in a system that has not had compressor burn out. If the system
has experienced burn out, it is recommended that the existing line set and indoor coil be replaced.

FIGURE 11

Page 8

STEP 5 -- REFRIGERANT PIPING -- Brazing Procedures

PIPING PANEL REMOVAL / PREPARING LINE SET

Remove piping panel to access service valves. Cut

1

ends of the refrigerant lines square (free from nicks or
dents) and debur the ends. The pipe must remain
round. Do not crimp the end of the line.

CUT AND DEBUR

LINE SET SIZE MATCHES

SERVICE VALVE CONNECTION

SERVICE VALVE

COPPER TUBE

REDUCER

CONNECTION

STUB

REFRIGERANT LINE

LINE SET SIZE IS SMALLER

THAN CONNECTION

CAP AND CORE REMOVAL

Remove service cap and core from both the suction

2

and liquid line service ports.

SERVICE PORT CAP

SERVICE PORT
CORE

LIQUID LINE SERVICE VALVE

SERVICE PORT
CORE

SERVICE
PORT CAP

SUCTION LINE

DO NOT CRIMP SERVICE VALVE

CONNECTOR WHEN PIPE IS

SMALLER THAN CONNECTION

SERVICE VALVE

ATTACH THE MANIFOLD GAUGE SET FOR BRAZING
LIQUID AND SUCTION LINE SERVICE VALVES

3

A Connect gauge set low pressure side to liquid line service valve (service port).
B Connect gauge set center port to bottle of nitrogen with regulator.
C With valve core removed from the suction line service port, nitrogen flow will have an exit point.

HIGHLOW

ATTACH

GAUGES

SUCTION LINE SERVICE PORT MUST BE OPEN

AND SERVICE PORT CORE REMOVED TO

ALLOW EXIT POINT FOR NITROGEN FLOW

SUCTION LINE

INDOOR

UNIT

LIQUID LINE

C

LIQUID LINE SERVICE

SUCTION

LINE

SERVICE

VALV E

VALV E

A

B

OUTDOOR

UNIT

NITROGEN

FIGURE 12

Page 9

SL18XC1 SERIES

CAUTION

Brazing alloys and flux contain materials which are
hazardous to your health.

Avoid breathing vapors or fumes from brazing
operations. Perform operations only in well-ventilated
areas.

Wear gloves and protective goggles or face shield to
protect against burns.
Wash hands with soap and water after handling brazing
alloys and flux.

WRAP SERVICE VALVES

To help protect service valve seals during brazing, wrap water-saturated cloths around service valve bodies and copper tube stubs. Use

4

additional water-saturated cloths under the valve body to protect the base paint.

FLOW NITROGEN

Flow regulated nitrogen (at 1 to 2 psig) through the refrigeration

5

gauge set into the valve stem port connection on the liquid service
valve and out of the suction valve stem port. See steps 3A, 3B and

3C on previous page and below for manifold gauge setup.

BRAZE LINE SET

Cloths must remain water-saturated throughout the brazing and

6

cool-down process.

A. Braze liquid line to liquid line service valve.

B. Braze suction line to suction service valve.

FIRE, PERSONAL INJURY, OR PROPERTY DAMAGE

may result if you do not wrap a water-saturated cloth around
both liquid and suction line service valve bodies and copper
tube stub while brazing the line set! The braze, when
complete, must be quenched with water to absorb any
residual heat.

Do not open service valves until refrigerant lines and
indoor coil have been leak-tested and evacuated. Refer
to Installation and Service Procedures manual found on
DAVENET.

WARNING

Danger of fire. Bleeding the refrigerant
charge from only the high side may result
in pressurization of the low side shell and
suction tubing. Application of a brazing
torch to a pressurized system may result
in ignition of the refrigerant and oil
mixture. Check the high and low
pressures before applying heat.

WARNING

SUCTION LINE

WATER-SATURATED CLOTHS

IMPORTANT !

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

LIQUID LINE

6B

6A

WHEN BRAZING LINE SET TO

SERVICE VALVES, POINT FLAME

AWAY FROM SERVICE VALVE.

SUCTION SERVICE PORT MUST

BE OPEN AND SERVICE PORT

CORE REMOVED TO ALLOW
EXIT POINT FOR NITROGEN

FLOW

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

7

valves to cool piping. Once piping is cool, remove all water-saturated cloths.

WATER-SATURATED

FIGURE 13

Page 10

CLOTHS

STEP 6 -- INSTALLING INDOOR EXPANSION VALVE

THIS OUTDOOR UNIT IS DESIGNED FOR USE IN SYSTEMS THAT USE A CHECK EXPANSION VALVE METERING DEVICE. SEE THE LENNOX SL18XC1
PRODUCT SPECIFICATION BULLETIN (EHB) FOR APPROVED EXPANSION VALVE KIT MATCH-UPS AND APPLICATION INFORMATION.

THE EXPANSION VALVE UNIT CAN BE INSTALLED INTERNAL OR
EXTERNAL TO THE INDOOR COIL. IN APPLICATIONS WHERE AN

TWO PIECE

PATCH PLATE

(UNCASED

COIL ONLY)

DISTRIBUTOR

TUBES

DISTRIBUTOR

ASSEMBLY

MALE EQUALIZER LINE

FITTING (SEE

EQUALIZER LINE

INSTALLATION FOR

FURTHER DETAILS)

SENSING BULB INSULATION IS REQUIRED
IF MOUNTED EXTERNAL TO THE COIL
CASING. SEE SENSING BULB
INSTALLATION FOR BULB POSITIONING.

(Uncased Coil Shown)

LIQUID LINE

ORIFICE

HOUSING

STUB

END

TEFLON
RING

EQUALIZER
LINE

EXPANSION

VALV E

®

LIQUID LINE

ASSEMBLY WITH

BRASS NUT

VAPOR

LINE

UNCASED COIL IS BEING INSTALLED IN A FIELD-PROVIDED
PLENUM, INSTALL THE CHECK EXPANSION VALVE IN A MANNER
WHICH PROVIDES ACCESS FOR FIELD SERVICING OF THE
EXPANSION VALVE. REFER TO BELOW ILLUSTRATION FOR
REFERENCE DURING INSTALLATION OF EXPANSION VALVE
UNIT.

®

TEFLON

RING

1. REMOVE THE FIELD-PROVIDED FITTING THAT TEMPORARILY RECON
NECTED THE LIQUID LINE TO THE INDOOR UNIT'S DISTRIBUTOR ASSEM

SENSING

LINE

LIQUID LINE

BLY.

2. INSTALL ONE OF THE PROVIDED TEFLON
STUBBED END OF THE EXPANSION VALVE AND LIGHTLY LUBRICATE THE
CONNECTOR THREADS AND EXPOSE SURFACE OF THE TEFLON
WITH REFRIGERANT OIL.

3. ATTACH THE STUBBED END OF THE EXPANSION VALVE TO THE LIQUID
LINE ORIFICE HOUSING. FINGER TIGHTEN AND USE AN APPROPRIATE
LY SIZED WRENCH TO TURN AN ADDITIONAL 1/2 TURN CLOCKWISE AS
ILLUSTRATED IN THE FIGURE ABOVE, OR 20 FT-LB.

4. PLACE THE REMAINING TEFLON
OF THE EXPANSION VALVE. LIGHTLY LUBRICATE CONNECTOR
THREADS AND EXPOSE SURFACE OF THE TEFLON
ERANT OIL.

5. ATTACH THE LIQUID LINE ASSEMBLY TO THE EXPANSION VALVE. FIN
GER 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.

9 O'CLOCK TO

3 O'CLOCK

BULB

12

®

BULB

9

WASHER AROUND THE OTHER END

12

11

1

10

8

7

®

RINGS AROUND THE

®

RING WITH REFRIG

ON LINES SMALLER THAN
7/8”, MOUNT SENSING
BULB BETWEEN THE 9 AND
3 O'CLOCK POSITIONS.

4

5

6

2

3

1/2 TURN

®

RING

SENSING BULB INSTALLATION

A. ATTACH THE SUCTION LINE SENSING BULB IN THE PROPER

ORIENTATION AS ILLUSTRATED TO THE RIGHT USING THE
CLAMP AND SCREWS PROVIDED.

NOTE - CONFIRM PROPER THERMAL CONTACT BETWEEN
SUCTION LINE AND CHECK EXPANSION BULB BEFORE IN
SULATING THE SENSING BULB ONCE INSTALLED.

B. CONNECT THE EQUALIZER LINE

FROM THE EXPANSION VALVE TO
THE EQUALIZER VAPOR PORT ON
THE SUCTION LINE. FINGER
TIGHTEN THE FLARE NUT PLUS
1/8 TURN (7 FT-LBS) AS ILLUS
TRATED BELOW.

9

10

11

12

1

8

7

EQUALIZER LINE INSTALLATION

REMOVE AND DISCARD EITHER THE FLARE SEAL CAP OR FLARE
NUT WITH COPPER FLARE SEAL BONNET FROM THE EQUALIZER
LINE PORT ON THE SUCTION LINE AS ILLUSTRATED IN THE FIGURE
TO THE RIGHT.

5

6

1/8 TURN

2

FLARE SEAL CAP

3

4

FIGURE 14

VAPOR LINE

BULB

ON 7/8” AND LARGER LINES,
MOUNT SENSING BULB AT
EITHER THE 4 OR 8 O'CLOCK
POSITION. NEVER MOUNT

12

BULB

OR

THE SENSING BULB ON
BOTTOM OF LINE.

NOTE - NEVER MOUNT

THE SENSING BULB ON

BOTTOM OF LINE.

FLARE NUT

COPPER FLARE
SEAL BONNET

MALE BRASS EQUALIZER
LINE FITTING

SUCTION LINE

Page 11

SL18XC1 SERIES

STEP 7 -- LEAK TEST

HIGHLOW

MANIFOLD GAUGE SET

OUTDOOR UNIT

B

TO SUCTION

SERVICE VALVE

NOTE - Position
canister to deliver
liquid refrigerant.

NITROGEN

CONNECT GAUGE SET

A Connect the high pressure hose of an HFC-410A manifold gauge set to the suction valve service port.

1

2

NOTE — Normally, the high pressure hose is connected to the liquid line port. However, connecting it
to the suction port better protects the manifold gauge set from high pressure damage.

B With both manifold valves closed, connect the cylinder of HFC-410A refrigerant to the center port of

the manifold gauge set.

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

TEST FOR LEAKS

After the line set has been connected to the indoor and outdoor units, check the line set connections
and indoor unit for leaks. Use the following procedure to test for leaks:

A With both manifold valves closed, connect the cylinder of HFC-410A refrigerant to the center port of

the manifold gauge set. Open the valve on the HFC-410A cylinder (vapor only).

B Open the high pressure side of the manifold to allow HFC-410A into the line set and indoor unit.

Weigh in a trace amount of HFC-410A. [A trace amount is a maximum of two ounces (57 g) refriger
ant or three pounds (31 kPa) pressure.] Close the valve on the HFC-410A cylinder and the valve on
the high pressure side of the manifold gauge set. Disconnect the HFC-410A cylinder.

C Connect a cylinder of nitrogen with a pressure regulating valve to the center port of the manifold

gauge set.

D Adjust nitrogen pressure to 150 psig (1034 kPa). Open the valve on the high side of the manifold gauge

set in order to pressurize the line set and the indoor unit.

E After a few minutes, open one of the service valve ports and verify that the refrigerant added to the

system earlier is measurable with a leak detector.

F After leak testing, disconnect gauges from service ports.

HFC-410A

A

FIGURE 15

Page 12

STEP 8 -- EVACUATION

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. Non­condensables and water suction combine with refrigerant to produce substances that corrode copper piping and compres
sor parts.

WARNING

Danger of Equipment Damage. Avoid deep vacuum system operation. Do not use the system compressor to
evacuate a system. Extremely low vacuums can cause internal arcing and compressor failure. Damage caused by
deep vacuum system operation will void warranty.

MANIFOLD

LOW

GAUGE SET

HIGH

LINE SET AND INDOOR COIL

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 suction line
service valve

B Connect high side of manifold gauge

set to liquid line service valve

C Connect micron gauge available

connector on the 1/4 SAE in-line tee.

D Connect the vacuum pump (with

vacuum gauge) to the center port of the
manifold gauge set. The center port line
will be used later for both the HFC-410A
and nitrogen containers.

NITROGEN

OUTDOOR

UNIT

A

A34000 1/4 SAE TEE WITH
SWIVEL COUPLER

500

C

MICRON

GAUGE

TO SUCTION

SERVICE VALVE

HFC-410A

VACUUM PUMP

B

FIGURE 16

EVACUATE LINE SET AND INDOOR COIL

The unit is shipped with a factory refrigerant charge. The
liquid and suction line valves were closed after final testing
at the factory. Do not operate these valves until the line set
and indoor coil have been evacuated and leak checked, or
the charge is lost.

NOTE - Do not use any portion of the factory charge for
purging or leak testing. The factory charge is for filling the
system only after a complete evacuation and leak check
has been performed.

Line set and indoor coil should be evacuated using the rec
ommended deep vacuum method of 500 microns. If deep
vacuum equipment is not available, the alternate triple
evacuation method may be used by following the specified
procedure.

TO LIQUID LINE
SERVICE VALVE

D

RECOMMEND

MINIMUM 3/8” HOSE

If vacuum must be interrupted during the evacuation pro
cedure, always break vacuum with dry nitrogen.

Deep Vacuum Method

The deep vacuum method requires a vacuum pump capa
ble of pulling a vacuum to 500 microns and a vacuum
gauge capable of accurately measuring this vacuum level.
The deep vacuum method is the most positive way of as
suring a system is free of air and water.

Watch the vacuum gauge as the system is pulling down.
The response of the gauge is an indicator of the condition
of the system (refer to figure 17).

With no leaks in the system, allow the vacuum pump to run
for 30 minutes minimum at the deep vacuum level.

Page 13

SL18XC1 SERIES

Deep Vacuum Gauge Response and

System Conditions

FIGURE 17

Triple Evacuation Method

The triple evacuation method should only be used when
system does not contain any water in liquid form and vacu
um pump is only capable of pulling down to 28 inches of
mercury (711mm Hg). Refer to figure 18 and proceed as
follows:

Triple Evacuation Sequence

EVACUATE

BREAK VACUUM WITH DRY NITROGEN

6. After the final evacuation sequence, confirm there are
no leaks in the system. If a leak is found, repeat the en
tire process after repair is made.

7. 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.

8. Disconnect the manifold hose from the vacuum pump
and connect it to an inverted cylinder of HFC*410A
positioned to deliver liquid refrigerant. Open the mani
fold gauge valve 1 to 2 psig in order to release the vac
uum in the line set and indoor unit.

9. Perform the following:

S Close manifold gauge valves.

S Shut off HFC*410A cylinder.

S Slowly open the service valves.

S Refer to the charging sticker on the unit to com

plete the outdoor unit installation.

Charging

The SL18XC1 unit is factory-charged with enough
HFC-410A refrigerant to accommodate a 15-foot length of
refrigerant piping. Charge should be checked and adjusted
using the tables provided on the charging procedure stick
er on the unit access panel. Detailed information is given in
the SL18XC1 Installation and Service Procedures manual,
which is available on LennoxPROS.com.

WAIT

EVACUATE

BREAK VACUUM WITH DRY NITROGEN

WAIT

EVACUATE

CHECK FOR TIGHT, DRY SYSTEM (IF IT HOLDS DEEP VACUUM)

CHARGE SYSTEM

FIGURE 18

1. Pull system down to 28 inches of mercury (711mm Hg)
and allow pump to continue operating for an additional
15 minutes.

2. Close manifold valves or valve at vacuum pump and
shut off vacuum pump.

3. Connect a nitrogen cylinder and regulator to system
and fill with nitrogen until system pressure is 2 psig.

4. Close nitrogen valve and allow system to stand for one
hour. During this time, dry nitrogen will diffuse through
out the system absorbing moisture.

5. Repeat this procedure as indicated in figure 18.

Homeowner Information

CAUTION

Before attempting to perform any service or mainte
nance, turn the electrical power to unit OFF at discon
nect switch.

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.

Homeowner Maintenance

The following maintenance may be performed by the
homeowner.

S Contact a licensed professional HVAC technician to

schedule a yearly inspection and maintenance appoint
ment for your equipment.

S Check the indoor unit filter each month and replace the

filter, if necessary.
Have your Lennox dealer show you where your indoor
unit filter is located. It will be either at the indoor unit (in
stalled internal or external to the cabinet) or behind a re
turn air grille in the wall or ceiling. Check the filter monthly
and clean or replace it as needed.
Disposable filters should be replaced with a filter of the
same type and size.

S Check the indoor unit drain line for obstructions monthly

during the cooling season.
The indoor evaporator coil is equipped with a drain pan

Page 14

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 ob
structions. (This would also apply to an auxiliary drain,
if installed.)

S Check the area around the outdoor unit monthly and re

move any obstructions that may restrict airflow to the
outdoor unit. This would include grass clippings, leaves,
or papers that may have settled around the unit.

S Trim shrubbery away from the unit and periodically

check for debris which collects around the unit.

S During the winter months, keep the snow level below the

louvered panels.

NOTE - The filter and all access panels must be in place
any time the unit is in operation. If you are unsure about the
filter required for your system, call your Lennox dealer for
assistance.

IMPORTANT !

Sprinklers and soaker hoses should not be installed
where they could cause prolonged exposure to the
outdoor unit by treated water. Prolonged exposure
of the unit to treated water (i.e., sprinkler systems,
soakers, waste water, etc.) will corrode the surface
of steel and aluminum parts, diminish performance
and affect longevity of the unit.

Thermostat Operation

See the ComfortSense® 7000 or iComfort®-enabled ther
mostat homeowner manual for instructions on how to op
erate your thermostat.

Pre-Service 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.

Professional Maintenance

Your heating and air conditioning system should be in
spected and maintained yearly (before the start of the cool
ing and heating seasons) by a licensed professional HVAC
technician. You can expect the technician to check the fol
lowing items. These checks may only be conducted by

a licensed professional HVAC technician.
Outdoor Unit

1. Inspect component wiring for loose, worn or damaged
connections. Also check for any rubbing or pinching of
wires. Confirm proper voltage plus amperage of outdoor
unit.

2. Check the cleanliness of outdoor fan and blade as
semblies. Check condition of fan blades (cracks).
Clean or replace them, if necessary.

3. Inspect base pan drains for debris and clean as neces
sary.

4. Inspect the condition of refrigerant piping and confirm
that pipes are not rubbing copper-to-copper. Also,
check the condition of the insulation on the refrigerant
lines. Repair, correct, or replace as necessary.

5. Test capacitor. Replace as necessary.

6. Inspect contactor contacts for pitting or burn marks.
Replace as necessary.

7. Check outdoor fan motor for worn bearings/bushings.
Replace as necessary.

8. Inspect and clean outdoor coils, if necessary and note
any damage to coils or signs of leakage.

NOTICE !

Failure to follow instructions will cause damage to
the unit.
This unit is equipped with an aluminum coil. Alu
minum coils may be damaged by exposure to solu
tions with a pH below 5 or above 9. The aluminum
coil should be cleaned using potable water at a
moderate pressure (less than 50psi). If the coil can
not be cleaned using water alone, Lennox recom
mends use of a coil cleaner with a pH in the range of
5 to 9. The coil must be rinsed thoroughly after
cleaning.
In coastal areas, the coil should be cleaned with
potable water several times per year to avoid corro
sive buildup (salt).

Indoor Unit (Air Handler or Furnace)

1. Inspect component wiring for loose, worn or damaged
connections. Confirm proper voltage plus amperage
indoor unit.

2. Inspect and clean or replace air filters in indoor unit.

3. Check the cleanliness of indoor blower and clean
blower, if necessary.

4. Inspect the evaporator coil (Indoor) drain pans and
condensate drains for rust, debris, obstructions, leaks
or cracks. Pour water in pans to confirm proper
drainage from the pan through to the outlet of the pipe.
Clean or replace as necessary.

5. Inspect and clean evaporator (indoor) coil, if necessary.

6. Inspect the condition of the refrigerant lines and con
firm that pipes are not rubbing copper-to-copper. Also,
ensure that refrigerant pipes are not being affected by
indoor air contamination. Check condition of insulation
on the refrigerant lines. Repair, correct, or replace as
necessary.

7. Inspect the duct system for leaks or other problems.
Repair or replace as necessary.

8. Check for bearing/bushing wear on indoor blower mo
tor. Replace as necessary.

9. Indoor unit inspections of gas- or oil-fired furnaces will
also include inspection and cleaning of the burners,
and a full inspection of the gas valve, heat exchanger
and flue (exhaust) system.

General System Test with System Operating

1. Your technician should perform a general system test.
He will turn on the air conditioner to check operating
functions such as the startup and shutoff operation.
He will also check for unusual noises or odors, and
measure indoor/outdoor temperatures and system
pressures as needed.

Page 15

SL18XC1 SERIES

2. The technician will check the refrigerant charge per
the charging sticker information on the outdoor unit.

3. Verify that system total static pressure and airflow set
tings are within specific operating parameters.

4. Verify correct temperature drop across indoor coil.

IMPORTANT

This performance check is ONLY valid on systems that have clean indoor and outdoor coils, proper airflow over coils,
and correct system refrigerant charge. All components in the system must be functioning properly to correctly perform
compressor operational check. (Accurate measurements are critical to this test as indoor system loading and outdoor
ambient can affect variations between low and high capacity readings).

SL18XC1 Start-Up and Performance Checklist

Customer Address

Indoor Unit Model Serial

Outdoor Unit Model Serial

Solar Module Mfg and Model Serial

Notes:

START-UP CHECKS

Refrigerant Type:

Rated Load Amps Actual Amps Rated Volts Actual Volts

Condenser Fan Full Load Amps Actual Amps:

COOLING MODE

Vapor Pressure: Liquid Pressure:

Supply Air Temperature: Ambient Temperature: Return Air Temperature:

HEATING MODE

Vapor Pressure: Liquid Pressure:

Supply Air Temperature: Ambient Temperature: Return Air Temperature:

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

Subcooling:

Saturated Condensing Temperature (A)

minus Liquid Line Temperature (B)

Approach:

Liquid Line Temperature (A)

minus Outdoor Air Temperature (B)

Indoor Coil Temp. Drop (18 to 22°F)

minus Supply Air Temperature (B)

A — B = SUBCOOLING

A — B = APPROACH

A — B = COIL TEMP DROPReturn Air Temperature (A)

Page 16