Lennox LGT156H User manual

2022
WARNING
Improper installation, adjustment, alteration, ser
vice or maintenance can cause property damage,
personal injury or loss of life. Installation and ser
vice must be performed by a licensed professional
HVAC installer or equivalent, service agency, or the
gas supplier
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in
jury. Take care while handling this equipment and
wear gloves and protective clothing.
Table of Contents
Dimensions Page 2.................................
Parts Arrangements Page 5.........................
Shipping and Packing List Page 6....................
General Page 6....................................
Unit Support Page 7................................
Duct Connection Page 8............................
Rigging Unit For Lifting Page 8.......................
Condensate Drains Page 8..........................
Gas Piping Page 9.................................
Pressure Test Gas Piping Page 9.....................
High Altitude Derate Page 10.........................
Download Mobile Service App Page 10.................
Electrical Connections - Power Supply Page 11.........
INSTALLATION
INSTRUCTIONS
LGT/LCT156H
LGT/LCT180H
LGT/LCT210H
LGT/LCT240H
LGT/LCT300S
(13 Ton)
(15 Ton)
(17.5 Ton)
(20 Ton)
(25 Ton)
ROOFTOP PACKAGED UNITS
508288-01
9/2022
Electrical Connections - Control Wiring Page 12.........
Blower Operation and Adjustments Page 13............
Cooling Start-Up Page 20............................
Temperature Thermistor Sensors Page 51..............
Gas Heat Start-Up Page 58...........................
Heating Operation and Adjustments Page 59............
Electric Heat Start-Up Page 59........................
Multi-Staged Air Volume Start-Up Page 60..............
Multi-Staged Air Volume & VAV Operation Page 62......
Hot Gas Reheat Start-Up Page 73.....................
Service Page 77....................................
Unit Controller Parameter Settings Page 82.............
RETAIN THESE INSTRUCTIONS FOR FUTURE REFERENCE
Use this QR code to download the mobile service app. Follow the prompts
to pair the app with the unit control system and configure the unit. Refer to the
“Download Mobile App” section in this manual and the Setup Guide provided
with this unit. The QR code is also available in the unit control area.
The app can be downloaded from the appropriate iOS or Android store.
Look for the following icon.
Attention!

Page 2
LGT/LCT156, 180, 210, 240, 300
WARNING
To prevent serious injury or death:
1- Lock-out/tag-out before performing maintenance.
2- If system power is required (e.g., smoke detector mainte
nance), disable power to blower, remove fan belt where
applicable, and ensure all controllers and thermostats are
set to the “OFF” position before
performing maintenance.
3- Always keep hands, hair, clothing, jewelry, tools, etc.,
away from moving parts.
LGT/LCT156H Unit Dimensions - Inches (mm) - Gas Heat Section Shown
4−1/4 (108)
BOTTOM POWER ENTRY
5 X 8 inches (127 X 203 mm)
BOTTOM SUPPL
Y
AIR OPENINGS
BOTTOM RETURN
AIR OPENING
28
(711)
28
(71
1)
4
(102)
4
(102)
12−3/8
(314)
12−3/8
(314)
20 (508) 20 (508)
15 (381)
60−1/2 (1537)
CENTER OF
GRAVITY
TOP VIEW
4−1/2
(114)
ALTERNATE (THRU THE BASE)
CONDENSATE DRAIN LOCATION
1−5/8 in. (41 mm) Diameter
18 (457)
28−3/8
(721)
5−5/8 (143)
107−3/4(2737)
BASE
91−1/8 (2315)
BASE
END VIEW
90−1/8
(2289)
28−3/4
(730)
CONDENSATE
DRAIN
5−3/8
(137)
3−1/4
(83)
54−1/4
(1378)
51
(1295)
91−1/8 (2315)
BASE
SIDE ELECTRICAL
INLETS
8−1/4
(210)
10−1/4
(260)
4
(102)
GAS SUPPLY
INLET
SIDE VIEW
FORKLIFT SLOTS
(Front and Left Side Only)
LIFTING HOLES
(For Rigging
Front and Back) 107−3/4(2737)
BASE
106−1/2
(2705)
FLUE
OUT LET
54−1/4
(1378)

Page 3
508288-01 9/2022
LGT/LCT180H, 210H Unit Dimensions - Inches (mm) - Gas Heat Section Shown
END VIEW
90−1/8
(2289)
28−3/4
(730 )
5−3/8
(137)
3−1/4
(83)
54−1/4
(1378)
51
(1295)
91−1/8 (2315)
BASE
8−1/4
(210)
10−1/4
(260)
4
(102)
4−1/4 (108)
BOTTOM POWER ENTRY
5 X 8 inches (127 X 203 mm)
BOTTOM SUPPL
Y
AIR OPENINGS
BOTTOM RETURN
AIR OPENING
28
(711)
28
(71
1)
4
(102)
4
(102)
12−3/8
(314)
12−3/8
(314) 20 (508)
15 (381)
60−1/2 (1537)
AA BB
CC
DD
CENTER OF
GRAVITY
TOP VIEW
4−1/2
(114)
20 (508)
SIDE VIEW
FORKLIFT SLOTS
(Front and Left Side Only)
132−5/8
(3369)
LIFTINGHOLES
(For Rigging
Front and Back)
25−3/8
(645)
107−3/4 (2737)
BASE
OPTIONAL
115 VOLT OUTLET
(Factory Installed Inside Unit)
FLUE
OUT LET
OPTIONAL
DISCONNECT
(Factory Installed)
CONDENSA
TE
DRAIN
ALTERNATE (THRU THE BASE)
CONDENSATE DRAIN LOCATION
1−5/8 in. (41 mm) Diameter
18 (457)
28−3/8
(721)
5−5/8 (143)
91−1/8
(2315)
133−1/8
(3394)
54−1/4
(1378)
ELECTRICAL
INLETS
GAS SUPPLY INLET
SIDE
GAS SUPPLY OUTLET
(For Bottom
Gas Supply Only)

Page 4
LGT/LCT156, 180, 210, 240, 300
LGT/LCT 240H & 300S Unit Dimensions - Inches (mm)-Gas Heat Section Shown
4−1/4 (108)
12−3/8
(314)
(314)
12−3/8
4
(102)
BOTTOM SUPPL
Y
AIR OPENINGS
BOTTOM RETURN
AIR OPENING
28
(711)
28
(711)
20 (508)
15 (381)
60−1/2 (1537)
AA BB
CC
DD
CENTER OF
GRAVITY
TOP VIEW
4−1/2
(114)
20 (508)
BOTTOM POWER ENTRY
5 X 8 inches (127 X 203 mm)
4
(102)
END VIEW
90−1/8
(2289)
28−3/4
(730)
5−3/8
(137)
3−1/4
(83)
54−1/4
(1378)
51
(1295)
91−1/8 (2315)
BASE
8−1/4
(210)
10−1/4
(260)
4
(102)
OPTIONAL
DISCONNECT
(Factory Installed)
CONDENSA
TE
DRAIN
FLUE
OUT LET
SIDE VIEW
FORKLIFT SLOTS
(Front and Left Side Only)
132−5/8
(3369)
LIFTINGHOLES
(For Rigging
Front and Back)
25−3/8
(645)
107−3/4 (2737)
BASE
OPTIONAL
115 VOLT OUTLET
(Factory Installed Inside Unit)
FLUE
OUT LET
ALTERNATE (THRU THE BASE)
CONDENSATE DRAIN LOCATION
1−5/8 in. (41 mm) Diameter
18 (457)
28−3/8
(721)
5−5/8 (143)
91−1/8
(2315)
133−1/8
(3381)
54−1/4
(1378)
ELECTRICAL
INLETS
GAS SUPPLY INLET
SIDE
GAS SUPPLY OUTLET
(For Bottom
Gas Supply Only)

Page 5
508288-01 9/2022
8.8.8.8
EVAPORATOR
COIL
COMBUSTION
AIR INDUCER
CONDENSER FANS
(3 ON 156,
4 ON 180, 210
6 on 240, 300)
CONDENSER
COILS
COMPRESSORS
(2 ON 156 - 1 & 3;
3 ON 180 - 1, 2, & 3
4 on 210, 240, & 300)
GAS VALVE BURNERS
FILTERS
(SIX - 24 X 24 X 2”)
DISCONNECT
(FACTORY-INSTALLED
OPTION)
REHEAT
COIL
BLOWERS
LGT156, 180, 210, 240, 300 PARTS ARRANGEMENT
BLOWER
MOTOR
ECONOMIZER
DAMPERS
(OPTIONAL)
CONDENSATE
DRAIN
BLOWER
INVERTER
UNIT
CONTROLLER
12
3
4
8.8.8.8
LCT156, 180, 210, 240, 300 PARTS ARRANGEMENT
ELECTRIC
HEAT
EVAPORATOR
COIL
FILTERS
(SIX - 24 X 24 X 2”)
REHEAT
COIL
BLOWER
MOTOR
ECONOMIZER
DAMPERS
(OPTIONAL)
BLOWERS
CONDENSATE
DRAIN
DISCONNECT
(FACTORY-INSTALLED
OPTION)
CONDENSER
COILS
BLOWER
INVERTER
UNIT
CONTROLLER
12
3
4
CONDENSER FANS
(3 ON 156,
4 ON 180, 210
6 on 240, 300)
COMPRESSORS
(2 ON 156 - 1 & 3;
3 ON 180 - 1, 2, & 3
4 on 210, 240, & 300)

Page 6
LGT/LCT156, 180, 210, 240, 300
Shipping and Packing List
Package 1 of 1 contains:
1- Assembled unit
Check unit for shipping damage. Receiving party should
contact last carrier immediately if shipping damage is found.
General
These instructions are intended as a general guide and
do not supersede local codes in any way. Authorities
having jurisdiction should be consulted before
installation.
The LGT156H gas/electric packaged rooftop unit is
available in 169, 000, 260,000, & 360,000 Btuh heating
input. The LGT180, 210, 240, & 300 gas/electric
packaged rooftop units are available in 260,000,
360,000, or 480,000 Btuh heating inputs.
The LCT cooling packaged rooftop unit is the same basic
design as the LGT unit except for the heating section.
Optional electric heat is factory- or field-installed in LCT
units.
LGT and LCT units have identical refrigerant circuits with
respective 13, 15, 17‐1/2, 20 and 25 ton cooling
capacities. 156H units contain two compressors;
compressor 1 is two speed and compressor 2 is fixed
speed. 180H units contain three compressors; all are
fixed speed. 210, 240 and 300 units contain four
compressors; all are fixed speed compressors.
Units come standard with a factory-installed, all-aluminum
condenser coil.
Units are available with an optional hot gas reheat coil
which provides a dehumidifying mode of operation. Refer
to Reheat Operation section.
Units are available with variable air volume or single-zone
variable air volume. Refer to the 9th character of the
model number to determine type of blower:
V - Variable Air Volume
M - Single-Zone Variable Air Volume
Units use R410A, an ozone-friendly HFC refrigerant.
Refer to the Cooling Start-Up section for precautions
when installing unit.
WARNING
Electric shock hazard and danger of
explosion. Can cause injury, death or
product or property damage. Turn off
gas and electrical power to unit before
performing any maintenance or
servicing operations on the unit. Follow
lighting instructions attached to unit
when putting unit back into operation
and after service or maintenance.
Requirements
See figure 1 for unit clearances.
UNIT CLEARANCES
C
DB
A
FIGURE 1
Optional
Outdoor
Air Hood
1Unit
Clearance
A
in.(mm)
B
in.(mm)
C
in.(mm)
D
in.(mm)
Top
Clearance
Service
Clearance
60
(1524)
36
(914)
36
(914)
66
(1676)
Unob
structed
Clearance to
Combus
tibles
36
(914) 1 (25) 1 (25) 1 (25) Unob structed
Minimum
Operation
Clearance
36
(914)
36
(914)
36
(914)
41
(1041)
Unob
structed
Note - Entire perimeter of unit base requires support when elevated above
mounting surface.
1Service Clearance - Required for removal of serviceable parts.
Clearance to Combustibles - Required clearance to combustible material
(gas units). On LCT units, see clearance to combustible materials outlined
on heater rating plate.
Minimum Operation Clearance - Required clearance for proper unit operation.

Page 7
508288-01 9/2022
NOTICE
Roof Damage!
This system contains both refrigerant and oil.
Some rubber roofing material may absorb oil,
causing the rubber to swell. Bubbles in the rubber
roofing material can 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.
Use of this unit as a construction heater or air conditioner
is not recommended during any phase of construction.
Very low return air temperatures, harmful vapors and
operation of the unit with clogged or misplaced filters will
damage the unit.
If this unit has been used for heating or cooling of
buildings or structures under construction, the following
conditions must be met or the warranty will be void:
 The vent hood must be installed per these installation
instructions.
 A room thermostat must control the unit. The use of
fixed jumpers that will provide continuous heating or
cooling is not allowed.
 A pre-filter must be installed at the entry to the return
air duct.
 The return air duct must be provided and sealed to
the unit.
 Return air temperature range between 55°F (13°C)
and 80°F (27°C) must be maintained.
 Air filters must be replaced and pre-filters must be
removed upon construction completion.
 The input rate and temperature rise must be set per
the unit rating plate.
 The heat exchanger, components, duct system, air
filters and evaporator coil must be thoroughly
cleaned following final construction clean-up.
 The unit operating conditions (including airflow,
cooling operation, ignition, input rate, temperature
rise and venting) must be verified according to these
installation instructions.
This appliance is not to be used by persons with reduced
physical, sensory or mental capabilities, or lack of
experience and knowledge, unless they have been given
supervision or instruction.
This appliance should not be used by children. Children
should be supervised to ensure they do not play with the
appliance.
IMPORTANT
The Clean Air Act of 1990 bans the intentional vent
ing of refrigerant (CFC's and HCFC's) as of July 1,
1992. Approved methods of recovery, recycling or
reclaiming must be followed. Fines and/or incar
ceration may be levied for non-compliance.
Unit Support
In downflow discharge installations, install the unit on a
non-combustible surface only. Unit may be installed on
combustible surfaces when used in horizontal discharge
applications or in downflow discharge applications when
installed on an LARMF18/36 roof mounting frame.
NOTE - Securely fasten roof frame to roof per local codes.
CAUTION
To reduce the likelihood of supply / return air by
pass and promote a proper seal with the RTU, duct
work / duct drops / diffuser assemblies must be
supported independently to the building structure.
A-Downflow Discharge Application
Roof Mounting with LARMF18/36
1- The LARMF roof mounting frame must be installed,
flashed and sealed in accordance with the
instructions provided with the frame.
2- The LARMF roof mounting frame should be square
and level to 1/16” per linear foot (5mm per linear
meter) in any direction.
3- Duct must be attached to the roof mounting frame
and not to the unit; supply and return plenums must
be installed before setting the unit.
Installer's Roof Mounting Frame
Many types of roof frames can be used to install the unit
depending upon different roof structures. Items to keep
in mind when using the building frame or supports are:
1- The base is fully enclosed and insulated, so an
enclosed frame is not required.
2- The frames or supports must be constructed with
non-combustible materials and should be square and
level to 1/16” per linear foot (5mm per linear meter)
in any direction.
3- Frame or supports must be high enough to prevent
any form of moisture from entering unit.
Recommended minimum frame height is 14”
(356mm).
4- Duct must be attached to the roof mounting frame
and not to the unit. Supply and return plenums must
be installed before setting the unit.

Page 8
LGT/LCT156, 180, 210, 240, 300
5- Units require support along all four sides of unit base.
Supports must be constructed of steel or suitably
treated wood materials.
NOTE-When installing a unit on a combustible surface for
downflow discharge applications, an LARMF18/36 roof
mounting frame is required.
B-Horizontal Discharge Applications
1- Units installed in horizontal airflow applications must
use an LARMFH18/24 horizontal roof mounting
frame. The supply air duct connects to the horizontal
supply air opening on the LARMFH18/24. The return
air duct connects to the unit horizontal return air
opening. Refer to unit dimensions.
2- Specified installation clearances must be maintained
when installing units. Refer to figure 1.
3- Top of support slab should be approximately 4”
(102mm) above the finished grade and located so no
run-off water from higher ground can collect around
the unit.
4- Units require support along all four sides of unit base.
Supports must be constructed of steel or suitably
treated wood materials.
Duct Connection
All exterior ducts, joints and openings in roof or building
walls must be insulated and weather-proofed with
flashing and sealing compounds in accordance with
applicable codes. Any duct passing through an
unconditioned space must be insulated.
CAUTION
In downflow applications, do not drill or punch
holes in base of unit. Leaking in roof may occur if
unit base is punctured.
Rigging Unit For Lifting
Rig unit for lifting by attaching four cables to holes in unit
base rail. See figure 2.
1- Detach wooden base protection before rigging.
2- Connect rigging to the unit base using both holes in
each corner.
3- All panels must be in place for rigging.
4- Place field‐provided H‐style pick in place just above
top edge of unit. Frame must be of adequate
strength and length. (H-style pick prevents damage
to unit.)
CAUTION - Do not
walk on unit.
IMPORTANT - ALL PANELS MUST
BE IN PLACE FOR RIGGING.
RIGGING
LIFTING POINT SHOULD BE DIRECTLY
ABOVE CENTER OF GRAVITY
*Maximum weight with all available
factory-installed accessories.
FIGURE 2
156
Kg.
LGT/LCT Unit *Weight
Lbs.
2499 1135
2613 1186
180
3054 1386
210
240, 300 3136 1424
Condensate Drains
Remove cap and make drain connection to the 1”
N.P.T. drain coupling provided on unit. A trap must be
installed between drain connection and an open vent
for proper condensate removal. See figure 3. It is
sometimes acceptable to drain condensate onto the
roof or grade; however, a tee should be fitted to the trap
to direct condensate downward. The condensate line
must be vented. Check local codes concerning
condensate disposal. Refer to pages 2, 3 and 4 for
condensate drain location.
Note - The drain pan is made with a glass reinforced
engineered plastic capable of withstanding typical joint
torque but can be damaged with excessive force. Tighten
pipe nipple hand tight and turn an additional quarter turn.

Page 9
508288-01 9/2022
FIGURE 3
Á
Á
Á
Á
Á
Á
Á
Á
Á
Á
Á
Á
Á
Á
UNIT
Minimum Pitch
1” (25 mm) per
10' (3 m) of line
MOUNTING
FRAME
OPEN VENT
CONDENSATE DRAIN CONNECTION
NOTE - Allow clearance to
open doors when installing
condensate piping.
CAULK AROUND
CONDENSATE
COUPLING
Connect Gas Piping
Before connecting piping, check with gas company or
authorities having jurisdiction for local code
requirements. When installing gas supply piping, length
of run from gas meter must be considered in determining
pipe size for 0.5” w.c. (.12kPa) maximum pressure drop.
Do not use supply pipe smaller than unit gas connection.
For natural gas units, operating pressure at the unit gas
connection must be a minimum of 4.7” w.c. (1.17kPa)
and a maximum of 10.5” (2.60kPa) w.c. For LP/propane
gas units, operating pressure at the unit gas connection
must be a minimum of 11” w.c. (2.74kPa) and a maximum
of 13.5” w.c. (3.36kPa).
When making piping connections a drip leg should be
installed on vertical pipe runs to serve as a trap for
sediment or condensate. A 1/8” N.P.T. plugged tap is
located on gas valve for test gauge connection. Refer to
Heating Start-Up section for tap location. Install a ground
joint union between the gas control manifold and the
main manual shut-off valve. See figure 4 for gas supply
piping entering outside the unit. See figure 5 for gas
supply entering through bottom of unit.
Compounds used on threaded joints of gas piping shall be
resistant to the action of liquified petroleum gases.
TO
GAS
SUPPLY
FIGURE 4
TO GAS
VALVE
MANUAL MAIN
SHUT-OFF VALVE
GAS PIPING
SUPPORT
GROUND
JOINT UNION
(REFER TO
LOCAL CODES) DRIP LEG
OUTSIDE OF UNIT GAS PIPING
DRIP LEG
MANUAL MAIN
SHUT-OFF VALVE
TO GAS
VALVE
GROUND
JOINT UNION
FIGURE 5
BOTTOM ENTRY GAS PIPING
CAP
EXISTING
SUPPLY
Pressure Test Gas Piping
When pressure testing gas lines, the gas valve must
be disconnected and isolated. Gas valves can be
damaged if subjected to more than 0.5 psig (3.48kPa).
See figure 6.

Page 10
LGT/LCT156, 180, 210, 240, 300
NOTE-Codes may require that manual main shut-off valve
and union (furnished by installer) be installed in gas line
external to unit. Union must be of the ground joint type.
After all connections have been made, check all piping
connections for gas leaks. Also check existing unit gas
connections up to the gas valve; loosening may occur
during installation. Use a leak detection solution or other
preferred means. Do not use matches candles or other
sources of ignition to check for gas leaks.
NOTE-In case emergency shut down is required, turn off
the main manual shut-off valve and disconnect main
power to unit. These devices should be properly labeled
by the installer.
GAS VALVE CAP
MANUAL MAIN
SHUT-OFF VALVE
FIGURE 6
PRESSURE TEST GAS LINE
CAUTION
Some soaps used for leak detection are corrosive
to certain metals. Carefully rinse piping thoroughly
after leak test has been completed. Do not use
matches, candles, flame or othe sources of ignition
to check for gas leaks.
WARNING
Danger of explosion. Can cause injury
or product or property damage. Do not
use matches, candles, flame or other
sources of ignition to check for leaks.
High Altitude Derate
Locate the high altitude conversion sticker in the unit
literature bag. Fill out the conversion sticker and affix next
to the unit nameplate. High altitude kits are available for
field-installation.
Refer to table 1 for high altitude adjustments.
TABLE 1
HIGH ALTITUDE DERATE
Unit Altitude Ft.* Gas Manifold Pressure
2000-4500 2000-4500 See Unit Nameplate
169KBtuh 4500 & Above Derate 2% / 1000 Ft.
Above Sea Level
260-380 KBtuh 4500 & Above Derate 4% / 1000 Ft.
Above Sea Level
*Units installed at 0-2000 feet do not need to be modified.
NOTE ‐ This is the only permissible derate for these units.
Download Mobile Service App
A-Mobile Device Requirements
 Android hardware requires 2GB RAM and a 2Ghz
core processor. Tablets are supported.
 Minimum Android 6.0 (Marshmallow) or higher.
Recommend Android 10 and Apple products require
iOS version 11 or higher.

Page 11
508288-01 9/2022
B-New Installations
Once the app is downloaded, refer to the Setup Guide
provided with this unit to pair the app to the unit control
system. Follow the setup wizard prompts to configure the
unit. See figure 7 for the app menu overview. If a mobile
device is unavailable or not pairing, refer to the Unit
Controller Setup Guide for start-up instructions.
MOBILE SERVICE APP MENU OVERVIEW
MENU
RTU MENU
SETUP
INSTALL
NETWORK
INTEGRATION
TEST AND BALANCETEST AND BALANCE
ALARM HISTORY
DATA TRENDING
FACTORY
RUNTIMES
SYSTEM DATA /
SENSORS / OUTPUTS
SERVICE
COMPONENT TEST
REPORT
ADVANCED
CONTROL
FIRMWARE UPDATE
SETTINGS
RTU OPTION
INSTALL
FIGURE 7
Electrical Connections - Power Supply
A-Wiring
Route fieldwiringinconduit betweenbottompower entry
and disconnect. See figure 8. This does not supersede
local codes or authorities having jurisdiction.
Do not apply power or close disconnect switch until
installation is complete. Refer to start-up directions.
Refer closely to unit wiring diagram.
Refer to unit nameplate for minimum circuit ampacity
and maximum fuse size.
1- Units are factory-wired for 240/460/575 volt supply.
For 208V supply, remove the insulated terminal
cover from the 208V terminal on the control
transformer. Move the wire from the transformer
240V terminal to the 208V terminal. Place the
insulated terminal cover on the unused 240V
terminal.
2- Route power through the bottom power entry area
and connect to line side of unit disconnect, circuit
breaker or terminal block. See unit wiring diagram.
3- Units With Optional 120v GFCI Outlet -
Route and connect separate 120v wiring to GFCI
outlets which do not have factory-installed wiring.
Route field wiring in conduit between bottom power
entry and GFCI. See figure 8.
SEAL
WATERTIGHT
RUN FIELD
WIRING IN
FIELD PRO
VIDED CONDUIT
SIDE ENTRY
KNOCKOUTS
BOTTOM
POWER ENTRY
OPTIONAL
120V GFI
MAKE-
UP BOX
FIGURE 8
FIELD WIRE ROUTING
B-Unbalanced Three-Phase Voltage
Units equipped with an inverter (VFD) are designed to
operate on balanced, three-phase power. Operating units
on unbalanced three-phase power will reduce the
reliability of all electrical components in the unit.
Unbalanced power is a result of the power delivery
system supplied by the local utility company.
Factory-installed inverters are sized to drive blower
motors with an equivalent current rating using balanced
three-phase power. When unbalanced three-phase
power is supplied; the installer must replace the existing
factory-installed inverter with an inverter that has a higher
current rating to allow for the imbalance. Use table 2 to
determine the appropriate replacement inverter.

Page 12
LGT/LCT156, 180, 210, 240, 300
TABLE 2
INVERTER UP-SIZING
Factory-Installed Inverter HP Replacement Inverter HP
2 5
3 7-1/2
5 10
7.5 15
10 20
Electrical Connections - Control Wiring
A-Thermostat Location
Room thermostat mounts vertically on a standard 2” X 4”
handy box or on any non-conductive flat surface.
Locate thermostat approximately 5 feet (1524mm)
above the floor in an area with good air circulation at
average temperature. Avoid locating the room
thermostat where it might be affected by:
-drafts or dead spots behind doors and in corners
-hot or cold air from ducts
-radiant heat from sun or appliances
-concealed pipes and chimneys
B-Wire Routing
Route thermostat cable or wires from subbase through
knockout provided in unit. Use 18 AWG wire for all
applications using remotely installed electro-mechanical
and electronic thermostats.
On hot gas reheat units, route wires from RH sensor or
remote switch through knockout provided in unit. For
sensor installations, use 22AWG stranded, two twisted
pairs, individually shielded, 100% aluminum shield with
drain wire and Teflon jacket.
IMPORTANT - Unless field thermostat wires are rated for
maximum unit voltage, they must be routed away from
line voltage wiring.
C-Wire Connections
The Unit Controller will operate the unit from a
thermostat or zone sensor based on the System Mode.
The default System Mode is the thermostat mode. Refer
to the Unit Controller Setup Guide to change the System
Mode. Use the mobile service app menu and select:
SETTINGS > INSTALL.
Note - Unit Controller is capable of up to four stages of
cooling in network control mode.
1- Default Thermostat Mode -
The Unit Controller will operate two stages of heating
and cooling based on thermostat demands. Install
thermostat assembly in accordance with instructions
provided with thermostat. See figure 9 for field wiring
and and refer to wiring diagrams on unit.
IMPORTANT-Terminal connections at the wall plate or
subbase must be made securely. Loose control wire
connections may result in intermittent operation.
FIGURE 9
FIELD WIRING WITH ELECTRONIC AND
ELECTRO-MECHANICAL THERMOSTATS
(Thermostat Mode)
J262C
10
11
12
J297
P297
1
2
3
4
5
6
7
8
9
10
24 V POWER
W1
W2
P262
A55
R
OCP
C
G
W1
W2
Y1
Y2
D
2- Zone Sensor Mode -
The Unit Controller will operate heating and cooling
based on the Unit Controller internal setpoints and the
temperature from the A2 zone sensor. An optional
Network Control Panel (NCP) can also be used to provide
setpoints. A thermostat or return air sensor can be used
as a back-up mode. Make zone sensor wiring
connections as shown in figure 10.
Note - Install sensor and make communication wiring
connections as shown in literature provided with sensor.
FIGURE 10
FIELD WIRING IN ZONE SENSOR MODE
(Zone Sensor Mode)
A2 SENSOR
INPUTS
SENSOR SENSOR
24VAC
RC
IAQ
HUM
AI1 AI2
TMP R
UNIT CONTROLLER
J298

Page 13
508288-01 9/2022
D-Hot Gas Reheat Units Only
1- Install humidity sensor in accordance with instructions
provided with sensor. A DDC input may be used to
initiate dehumidification instead of a sensor.
2- Make wiring connections as shown in figure 9 for
Thermostat Mode and figure 10 for Zone Sensor
Mode. In addition, connect either a humidity sensor
or a dehumidification input. See figure 11 or 12 for
humidity sensor wiring and figure 13 for
dehumidification input wiring.
Humidity Sensor Cable Applications:
Wire runs of 50 feet (mm) or less:
Use two separate shielded cables containing 20AWG
minimum, twisted pair conductors with overall shield.
Belden type 8762 or 88760 (plenum) or equivalent.
Connect both cable shield drain wires to TB1-7 as shown
in figure 11.
Wire runs of 150 feet (mm) or less:
Use two separate shielded cables containing 18AWG
minimum, twisted pair conductors with overall shield.
Belden type 8760 or 88760 (plenum) or equivalent.
Connect both cable shield drain wires to TB1-7 as shown
in figure 11.
Wire runs over 150 feet (mm):
Use a local, isolated 24VAC transformer such as Lennox
cat #18M13 (20VA minimum) to supply power to RH
sensor as shown in figure 12. Use two shielded cables
containing 20AWG minimum, twisted pair conductors
with overall shield. Belden type 8762 or 88760 (plenum)
or equivalent.
FIGURE 11
FIELD WIRING REHEAT UNITS (Using A Humidity
Sensor With Less Than 150 Ft. Wire Runs)
9
8
J298
P298 1
2
3
4
5
6
7
10
A91
VIN
VO
GND
R
C
AI-1
HUM
TMP
AI2
C
R
UNUSED
WIRE
NOT
CONNECTED
NOT
CONNECTED
DRAIN
A55 UNIT
CONTROLLER
FIGURE 12
FIELD WIRING REHEAT UNITS (Using A Humid
ity Sensor With More than 150 Ft. Wire Runs)
ISOLATED 24V
TRANSFORMER
9
8
J298P298
1
2
3
4
5
6
7
10
A91
VIN
VO
GND
R
C
AI-1
HUM
TMP
AI2
C
R
NOT
CONNECTED
NOT
CONNECTED
DRAIN
A55 UNIT
CONTROLLER
FIGURE 13
FIELD WIRING REHEAT UNITS
(Using A Dehumidification Switch)
7
10
8
9
R
DI−4
C
Use 24 VAC (R) from any terminal
available on P299−2, −5, or −7.
P299
DEHUMIDIFICATION
SWITCH
Blower Operation and Adjustments
Supply Air Staged Units - The blower rotation will
always be correct on units equipped with an inverter.
Checking blower rotation is not a valid method of
determining voltage phasing for incoming power.
Supply Air Staged Units and Units Equipped With
Optional Voltage or Phase Detection - The Unit
Controller checks the incoming power during start-up. If
the voltage or phase is incorrect, the Unit Controller will
display an alarm and the unit will not start.
A-Blower Operation
Refer to the Unit Controller Setup Guide to energize
blower. Use this mobile service app menu:
SERVICE > TEST > BLOWER

Page 14
LGT/LCT156, 180, 210, 240, 300
Instructions provided with the thermostat may also be
used to initiate blower only (G) demand. Unit will cycle on
thermostat demand. The following steps apply to
applications using a typical electro-mechanical
thermostat.
1- Blower operation is manually set at the thermostat
subbase fan switch. With fan switch in ON position,
blowers will operate continuously.
2- With fan switch in AUTO position, the blowers will
cycle with demand. Blowers and entire unit will be off
when system switch is in OFF position.
IMPORTANT
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se
quentially to ensure correct compressor and blower*
rotation and operation. Compressor and blower are
wired in phase at the factory. Power wires are color-
coded as follows: line 1-red, line 2-yellow, line 3-blue.
1-Observe suction and discharge pressures and blow
er* rotation on unit start-up.
2-Suction pressure must drop, discharge pressure must
rise and blower* rotation must match rotation marking.
If pressure differential is not observed or blower* rota
tion is not correct:
3-Disconnect all remote electrical power supplies.
4-Reverse any two field-installed wires connected to
the line side of S48 disconnect or TB13 terminal strip.
Do not reverse wires at blower contactor.
5-Make sure the connections are tight.
Discharge and suction pressures should operate at
their normal start‐up ranges.
*Supply air inverter blower motors should rotate in the
correct direction; verify scroll compressor rotation
separately. Contact technical support if the blower is
rotating incorrectly.
WARNING
1-Make sure that unit is installed in accordance with the
installation instructions and applicable codes.
2-Inspect all electrical wiring, both field‐ and factory‐
installed, for loose connections. Tighten as required.
3-Check to ensure that refrigerant lines do not rub against
the cabinet or against other refrigerant lines.
4-Check voltage at disconnect switch. Voltage must be
within range listed on nameplate. If not, consult power
company and have voltage condition corrected before
starting unit.
5-Make sure filters are new and in place before start‐up.
B-Blower Access
1- Disconnect jack/plug connector to blower motor. Also
disconnect jack/plug connector heating limit switches
on gas units.
2- Remove screws on either side of blower assembly
sliding base. See figure 15.
3- Pull base toward outside of unit.
C-Determining Unit CFM
IMPORTANT - Multi-staged supply air units are
factory-set to run the blower at full speed when there is a
blower (G) demand without a heating or cooling
demand. Refer to the field-provided, design specified
CFM for all modes of operation. Use the following
procedure to adjust motor pulley to deliver the highest
CFM called for in the design spec. See Inverter Start-Up
section to set blower CFM for all modes once the motor
pulley is set.
Variable Air Volume Units - Refer to the Variable Air
Volume Start-Up section.
1- The following measurements must be made with a
dry indoor coil. Run blower (G demand) without a
cooling demand. Measure the indoor blower shaft
RPM. Air filters must be in place when measurements
are taken.
2- With all access panels in place, measure static
pressure external to unit (from supply to return).
Blower performance data is based on static pressure
readings taken in locations shown in figure 14.
Note - Static pressure readings can vary if not taken
where shown.
3- Referring to page 17, use static pressure and RPM
readings to determine unit CFM. Use page 18 when
installing units with any of the optional accessories
listed.
4- The blower RPM can be adjusted at the motor pulley.
Loosen Allen screw and turn adjustable pulley
clockwise to increase CFM. Turn counterclockwise to
decrease CFM. See figure 15. Do not exceed
minimum and maximum number of pulley turns as
shown in table 3.
TABLE 3
MINIMUM AND MAXIMUM PULLEY ADJUSTMENT
Belt Minimum Turns Open Maximum Turns Open
A Section No minimum 5
B Section 1* 6
*No minimum number of turns open when B belt is used on
pulleys 6” O.D. or larger.

Page 15
508288-01 9/2022
FIGURE 14
LOCATION OF STATIC PRESSURE READINGS
SUPPLY AIR
READING
LOCATION
SUPPLY RE
TURN
INSTALLATIONS WITH DUCTWORK
SUPPLY RE
TURN
INSTALLATIONS WITH CEILING DIFFUSERS
MAIN
DUCT RUN
FIRST BRANCH
OFF OF MAIN RUN
DIFFUSER
ROOFTOP UNIT ROOFTOP UNIT
SUPPLY AIR
READING
LOCATION
RETURN AIR
READING LOCATION
RETURN AIR
READING
LOCATION
BLOWER ASSEMBLY
TO INCREASE BELT TENSION
1-Loosen four screws securing blower motor to
sliding base.
2-Turn adjusting screw to the left, or counter
clockwise, to move the motor downward and
tighten the belt.
3-Tighten four screws.
TO INCREASE CFM
LOOSEN ALLEN SCREW &
TURN PULLEY CLOCKWISE
TO DECREASE CFM
TURN PULLEY
COUNTERCLOCKWISE
FIGURE 15
BLOWER
WHEEL
BLOWER
MOTOR
PULLEY
BLOWER
ASSEMBLY
SLIDING BASE
BELT TENSION
ADJUSTING
SCREW
LOOSEN (4) SCREWS TO
ADJUST BELT TENSION
REMOVE SCREWS TO
SLIDE BLOWER
ASSEMBLY OUT OF UNIT
PULLEY
MOTOR ALLEN
SCREW
SIDE VIEW

Page 16
LGT/LCT156, 180, 210, 240, 300
D-Blower Belt Adjustment
Maximum life and wear can be obtained from belts only if
proper pulley alignment and belt tension are maintained.
Tension new belts after a 24-48 hour period of operation.
This will allow belt to stretch and seat into pulley grooves.
Make sure blower and motor pulley are aligned. See figure
16.
1- Loosen four screws securing blower motor to sliding
base. See figure 15.
2- To increase belt tension -
Turn belt tension adjusting screw to the left, or
counterclockwise, to tighten the belt. This increases
the distance between the blower motor and the
blower housing.
To loosen belt tension -
Turn the adjusting screw to the right, or clockwise to
loosen belt tension.
3- Tighten four screws securing blower motor to sliding
base once adjustments have been made.
FIGURE 16
PULLEY ALIGNMENT
BELT BLOWER
PULLEY
MOTOR
PULLEY
NOT ALIGNED
ALIGNED
E-Check Belt Tension
Overtensioning belts shortens belt and bearing life.
Check belt tension as follows:
1- Measure span length X. See figure 17.
2- Apply perpendicular force to center of span (X) with
enough pressure to deflect belt 1/64” for every inch
of span length or 1.5mm per 100mm of span length.
Example: Deflection distance of a 40” span would be
40/64” or 5/8”.
Example: Deflection distance of a 400mm span
would be 6mm.
3- Measure belt deflection force. For a used belt, the
deflection force should be 5 lbs. (35kPa) . A new belt
deflection force should be 7 lbs. (48kPa).
A force below these values indicates and
undertensioned belt. A force above these values
indicates an overtensioned belt.
MEASURE BELT TENSION
FIGURE 17
DEFLECTION 1/64” PER INCH OF SPAN
OR 1.5mm PER 100mm OF SPAN
FORCE
F-Field-Furnished Blower Drives
For field-furnished blower drives, use page 16 to
determine BHP and RPM required. Reference page 17 to
determine the manufacturer's model number.
G-Minimum Airflow For Optional Electric Heat
Electric Heat kW Minimum CFM
15 5200
30 5200
45 5200
60 5200
90 6000

Page 17
508288-01 9/2022
BLOWER TABLES

Page 18
LGT/LCT156, 180, 210, 240, 300
Accessory Air Resistance

Page 19
508288-01 9/2022
MANUFACTURER'S NUMBERS
Same as 508336. Not as of 12/5 markup.

Page 20
LGT/LCT156, 180, 210, 240, 300
Cooling Start-Up
IMPORTANT-The crankcase heater must be energized
for 24 hours before attempting to start compressor. Set
thermostat so there is no demand to prevent
compressors from cycling. Apply power to unit.
NOTE - These units must not be used as a
“construction heater” at any time during any phase of
construction. Very low return air temperatures,
harmful vapors and misplacement of the filters will
damage the unit and its efficiency. Additionally, a unit
which will be subject to cold temperatures when not in
operation must have a vapor barrier installed to seal
the duct connections. Failure to protect the unit from
moisture laden air or harmful vapors (generated from
the construction process and temporary combustion
heating equipment) will cause corrosive condensation
within the unit. Failure to properly protect the unit in
this situation will cause electrical and electronic
component failure and could affect the unit warranty
status.
A-Preliminary Checks
1- Make sure that unit is installed in accordance with the
installation instructions and applicable codes.
2- Inspect all electrical wiring, both field‐ and
factory‐installed, for loose connections. Tighten as
required.
3- Check to ensure that refrigerant lines do not rub against
the cabinet or against other refrigerant lines.
4- Check voltage at disconnect switch. Voltage must be
within range listed on nameplate. If not, consult
power company and have voltage condition
corrected before starting unit.
5- Make sure filters are in place before start‐up.
B-Start-Up
Supply Air Staged Blower - Refer to the Multi-Staged Air
Volume Start-Up section.
1- Initiate first and second stage cooling demands using
this mobile service app menu path:
SERVICE > TEST > COOLING > COOL4
Instructions provided with the thermostat may also be
used to initiate cooling.
2- First-stage thermostat demand will energize indoor
blower in Low Cooling CFM and associated
first-stage compressors. Second-stage thermostat
demand will energize indoor blower in High Cooling
CFM and all remaining compressors.
3- 156 -
Units contain two refrigerant circuits or systems. See
figure 18.
180 -
Units contain three refrigerant circuits or systems.
See figure 19.
210, 240, 300 -
Units contain four refrigerant circuits or systems. See
figure 20.
4- Each refrigerant circuit is separately charged with
R410A refrigerant. See unit rating plate for correct
amount of charge.
5- Refer to the Refrigerant Check and Charge section to
check refrigerant charge.
C-R410A Refrigerant
Units charged with R410A refrigerant operate at much
higher pressures than R22. The expansion valve and
liquid line drier provided with the unit are approved for use
with R410A. Do not replace them with components
designed for use with R22.
R410A refrigerant is stored in a pink cylinder.
IMPORTANT
Mineral oils are not compatible with R410A. If oil
must be added, it must be a polyol ester oil.
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures of 0-800 on the high side and a low
side of 30” vacuum to 250 psi with dampened speed to
500 psi. Gauge hoses must be rated for use at up to 800
psi of pressure with a 4000 psi burst rating.