Lennox LGA060 Guide

10/08
*2P1008*
504,875M
*P504875M*
LGA/LGC036, 042, 048, 060, 072
LGA/LGC090, 102, 120, 150,
LGA/LGC156, 180, 210, 240, 300S
LGA/LGC248, 300H, 360
©2006
Litho U.S.A.
504,875M
10/2008
Supersedes 1/2006
WHAT TO DO IF YOU SMELL GAS:
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings ex-
actly could result in serious injury
death or property damage.
WARNING
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
Installation and service must be per-
formed by a qualified installer, ser-
vice agency or the gas supplier.
DDo not try to light any appliance.
DDo not touch any electrical switch; do not
use any phone in your building.
DImmediately call your gas supplier from a
neighbor’s phone. Follow the gas suppli-
er’s instructions.
DIf you cannot reach your gas supplier, call
the fire department.
DExtinguish any open flames.
ROOFTOP
UNITS
READ ALL INSTRUCTIONS IN THIS MANUAL
AND RETAIN FOR FUTURE REFERENCE
LGA240 SHOWN
See unit nameplate for manufacturer
and address.
FBR113270
(3, 3−1/2, 4, 5, and 6 TONS)
(7−1/2, 8-1/2, 10, and 12-1/2 TONS)
(13, 15, 17-1/2, 20, and 25 TONS)
(20, 25, and 30 TONS)
DLeave the building immediately.

Page 1
LGA/LGC036, 042, 048, 060, 072 Parts Arrangement
CONDENSER FAN
HEAT EXCHANGER
COMPRESSOR
EVAPORATOR COIL
CONDENSATE
DRAIN
BLOWER
TB1
COMBUSTION
AIR INDUCER
GAS VALVE
BURNERS
FILTERS
DISCONNECT
(OPTIONAL)
ECONOMIZER
(OPTIONAL)
120V GFCI OUTLET
(OPTIONAL)
LGA/LGC090, 102, 120 and 150 Parts Arrangement
COMBUSTION AIR
INDUCER
120V GFCI OUTLET
(Factory−installed option)
BLOWER
MOTOR
CONDENSER FANS
CONDENSER
COIL
COMPRESSORS BURNERS
GAS VALVE
HEAT EXCHANGER
TUBES
BLOWER
CONDENSATE
DRAIN
FILTERS
ECONOMIZER DAMPERS
(OPTIONAL)
DISCONNECT
(Factory−installed
option)
EVAPORATOR
COIL

Page 2
LGA/LGC156, 180, 210, 240 and 300S Parts Arrangement
COMBUSTION AIR
INDUCER
EVAPORATOR
COIL
BLOWER MOTOR
CONDENSER FANS
CONDENSER
COILS
COMPRESSORS
(3 COMPRESSORS ON
LGA/LGC156 & 180 UNITS)
BURNERS
GAS VALVE HEAT EXCHANGER TUBES
BLOWERS
CONDENSATE
DRAIN
FILTERS
ECONOMIZER DAMPERS
(OPTIONAL)
CONTROL BOX
120V GFCI OUTLET
(Factory−installed option)
DISCONNECT
(Factory−installed
option)
LGA/LGC248, 300H and 360 Parts Arrangement
COMBUSTION AIR
INDUCER
EVAPORATOR
COIL
CONDENSER FANS
CONDENSER
COILS
COMPRESSORS
(−248 AND −300H HAVE
4 COMPRESSORS)
BURNERS
GAS VALVE
HEAT EXCHANGER
TUBES
CONDENSATE
DRAIN
FILTERS
ECONOMIZER DAMPERS
(OPTIONAL)
BLOWERS
BLOWER
MOTOR

Page 3
Safety
1− Keep unit area clear and free of combustible
materials, gasoline and other flammable vapors and
liquids.
2− Do not obstruct air flow to unit. Unit must receive
an unobstructed flow of combustion and
ventilating air.
WARNING
Danger of explosion and fire. Failure to
follow safety warnings exactly could
result in dangerous operation, serious
injury, death or property damage.
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 qualified installer, ser-
vice agency or the gas supplier
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon-
nect switch(es). Unit may have multiple
power supplies.
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of
California to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact
your supervisor.
P.O. Box 79990
Dallas, TX 75379−9900 USA
CAUTION
Label all wires prior to disconnection when servic-
ing controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.
WARNING
Danger of electrical shock, explosion
and fire. Improper servicing could
result in dangerous operation, serious
inujry, death or property damage.
WARNING
Do not use this furnace if any part has been under
water. A flood−damaged furnace is extremely dan-
gerous. Attempts to use the furnace can result in
fire or explosion. A qualified service agency
should be contacted to inspect the furnace and to
replace all gas controls, control system parts,
electrical parts that have been wet or the furnace
if deemed necessary.
WARNING
Danger of explosion. Can cause injury
or product or property damage. Should
the gas supply fail to shut off or if
overheating occurs, shut off the gas
valve to the furnace before shutting off
the electrical supply.
Unit Operation
FOR YOUR SAFETY READ BEFORE LIGHTING
BEFORE LIGHTING smell all around the furnace area for
gas. Be sure to smell next to the roof because some gas is
heavier than air and will settle on the roof.
Use only your hand to push in or turn the gas control knob.
Never use tools. If the knob will not push in or turn by
hand, do not try to repair it, call a qualified service
technician. Force or attempted repair may result in a fire
or explosion.
The unit is equipped with an automatic spark ignition
system. There is no pilot. In case of a safety shutdown,
move thermostat switch to OFF and return the thermostat
switch to HEAT. Electromechanical thermostat is shown
in figure 1. For logic units and units with electronic
temperature controls, shut off the main disconnect and
then turn it on to reset the ignition control.

Page 4
TYPICAL ELECTROMECHANICAL THERMOSTAT
FIGURE 1
Placing Unit Into Operation
WARNING
Danger of explosion and fire. Can cause
injury or product or property damage.
You must follow these instructions ex-
actly.
Gas Valve Operation White Rodgers 36E (figure 2),
Honeywell VR8205M (figure 3), and Honeywell
VR8205Q/VR8305Q (figure 4)
1− Set thermostat to lowest setting.
2− Turn off all electrical power to furnace.
3− This furnace is equipped with an ignition device which
automatically lights the burner. Do not try to light the
burner by hand.
4− Open or remove the heat section access panel.
5− VR8205, & VR8305 −
Turn the knob on the gas valve clockwise to
OFF". Do not force.
36E −
Turn the knob 180° either way to OFF".
WHITE RODGERS 36E GAS VALVE
NO
OFF
Gas valve knob is shown
in OFF position.
FIGURE 2
MANIFOLD
PRESSURE
TAP (SIDE)
INLET
PRESSURE
TAP (SIDE)
ON
OFF
HONEYWELL VR8205M SERIES GAS VALVE
Gas valve knob is shown in OFF position.
FIGURE 3
MANIFOLD
PRESSURE
TAP
INLET
PRESSURE
TAP
HONEYWELL VR8205Q/VR8305Q SERIES GAS VALVE
Gas valve knob is shown in OFF position.
FIGURE 4
LOW FIRE
ADJUSTMENT
HIGH FIRE
ADJUSTMENT
INLET
PRESSURE
TAP
MANIFOLD
PRESSURE
TAP
6− Wait five (5) minutes to clear out any gas. If you then
smell gas, STOP! Immediately call your
gas supplier from a neighbor’s phone. Follow the gas
supplier’s instructions. If you do not smell gas, go to
the next step.
7− VR8205, & 8305 −
Turn the knob on the gas valve counterclockwise
to ON". Do not force.
36E −
Turn the knob 180° either way to ON".
8− Close or replace the heat section access panel.
9− Turn on all electrical power to furnace.
10− Set thermostat to desired setting.
11− The ignition sequence will start.
12− If the furnace does not light the first time (gas line not
fully purged), it will attempt up to two more ignitions
before locking out.
13− If lockout occurs, repeat steps 1 through 10.
14− If the furnace will not operate, follow the instructions
Turning Off Gas to Furnace" and call your service
technician or gas supplier.
Turning Off Gas to Furnace
1− If using an electromechanical thermostat, set to the
lowest setting.
2− Before performing any service, turn off all electrical
power to the furnace.

Page 5
3− Open or remove the heat section access panel.
4− VR8205, & VR8305 −
Turn the knob on the gas valve clockwise to
OFF". Do not force.
36E −
Turn the knob 180° either way to OFF".
5− Close or replace the heat section access panel.
WARNING
Danger of explosion. Can cause injury or
death. Do not attempt to light manually.
Unit has a direct spark ignition system.
Burner Flame
WARNING
Danger of explosion and fire. Can cause
injury or product or property damage.
Periodically inspect burner flame to en-
sure proper unit operation.
The primary air is permanently set for normal operation.
The flame will be basically blue with some clear yellow
streaking in the end of the flame. Inspect the burner flame
periodically during the heating season using the
inspection port provided on the burner access panel.
Flue Passage and Vent Inspection
Annually, before heating season, inspect the combustion
air louvers, vent cap, heat exchanger, burners and
combustion air inducer for corrosion, deterioration or
deposits of debris. Remove any obstructions or blockage.
See figures 5 and 6.
Service
To maintain efficiency and longevity, your equipment
must be serviced yearly by a qualified service technician.
Failure to provide proof of service can void warranty.
CAUTION
Label all wires prior to disconnection when ser-
vicing controls. Wiring errors can cause improper
and dangerous operation. Verify proper operation
after servicing.
HEAT EXCHANGER ASSEMBLY (036−072)
BURNERS
COMBUSTION
AIR
INDUCER
VENT
CONNECTOR
GAS
VALVE
HEAT
EXCHANGER TUBES
BAFFLE
FLUE BOX
FIGURE 5
BURNER
COMBUSTION
AIR INDUCER
VENT
CONNECTOR
GAS VALVE
HEAT
EXCHANGER
TUBE
HEAT EXCHANGER ASSEMBLY (090−360)
FIGURE 6

Page 6
Servicing Filter
Units are equipped with the number of filters shown in
table 1. Filters should be checked monthly and replaced
when necessary with filters of like kind and size. Take note
of air flow direction marking on filter frame when
reinstalling filters. See figure 7.
REMOVE FILTERS
PULL TO REMOVE
FILTERS
FIGURE 7
NOTE − Filters must be ULC approved or equivalent for
use in Canada.
TABLE 1
NUMBER AND SIZE OF FILTER BY UNIT
LGA/LGC Unit Qty Filter Size − inches (mm)
036, 042, 048, 060, 072 216 X 25 X 2 (406 X 635 X 51)
090, 102, 120, 150 418 X 24 X 2 (457 X 610 X 51)
156, 180, 210, 240, 300S 624 X 24 X 2 (610 X 610 X 51)
248, 300H, 360 12 20 X 20 X 2 (508 X 508 X 51)
Lubrication
All motors are lubricated at the factory. No further
lubrication is required.
Blower shaft bearings are prelubricated. For extended
bearing life, relubricate at least once every two years
with a lithium base grease, such as Alvania 3 (Shell Oil),
Chevron BRB2 (Standard Oil) or Regal AFB2 (Texas
Oil). Use a hand grease gun for relubrication. Add only
enough grease to purge through the bearings so that a
bead of grease appears at the seal lip contacts.
Manifold Pressures
Manifold pressures are shown in table 2. Refer to figures
2, 3, and 4 to locate pressure ports.
TABLE 2
MANIFOLD PRESSURES in.wg. (kPa)
Natural Gas Propane (LP) Gas
LGA/LGC Unit 1st Stg.+
0.2(+.05)
2nd Stg.+
0.3 (+.08)
1st Stg.+
0.2 (+.05)
2nd Stg.+
0.3 (+.08)
036, 042, 048, 060,
072 Std./High Heat NA 3.5 (0.87) NA 10.5 (2.61)
036, 042, 048, 060,
072 Dual Heat
1.9
(0.47)
3.5
(0.87)
5.3
(1.32)
10.5
(2.61)
090 through 360 1.6
(0.40)
3.7
(0.92)
5.5
(1.37)
10.5
(2.61)
Burners
Clean the burners as follows:
1− Turn off the electrical power and the gas supply to the
unit.
2− Open or remove the burner compartment access
panel.
3− Remove two screws securing burners to burner
support and lift the burners from the orifices. See
figure 8. Clean as necessary. Spark gap on ignition
electrode must be properly set. Refer to the Heating
Adjustment section in the installation instructions.
4− Replace burners and screws securing burner.
Replace the burner compartment access panel.
5− Turn on the electrical power and the gas supply to the
unit. Follow the operating instructions attached to the
unit and use the inspection port in the access panel
to check the flame.
BURNER BOX ASSEMBLY
FIGURE 8
GAS MANIFOLD
FLAME
SENSOR
GAS
VALVE
BURNERS

Page 7
Combustion Air Inducer
A combustion air inducer proving switch checks
combustion air inducer operation before allowing power
to the gas controller. The gas controller will not operate if
the inducer is obstructed.
Under normal operating conditions, the combustion air
inducer wheel should be checked and cleaned prior to the
heating season. However, it should be examined
periodically during the heating season to establish an
ideal cleaning schedule.
Clean the combustion air inducer as follows:
1− Turn off the electrical power and the gas supply to the
unit.
2− Disconnect the pressure switch air tubing from the
combustion air inducer port.
3− Remove and retain the screws securing the
combustion air inducer to the flue box. Remove and
retain two screws from the bracket supporting the
vent connector. See figures 5 and 6.
4− Clean the inducer wheel blades with a small brush
and wipe off any dust from the housing. Clean
accumulated dust from the front of the flue box cover.
5− Return the combustion air inducer motor and the vent
connector to their original location and secure with
retained screws. It is recommended that the
combustion air inducer gasket be replaced during
reassembly.
6− Use a small brush to clean the combustion air inlet
louvers on the heat access panel.
Flue Passageway and Flue Box
1− Remove the combustion air inducer assembly as
described in the Combustion Air Inducer subsection.
2− Remove the flue box cover. Clean the flue box with a
wire brush as required.
3− Clean the tubes with a wire brush.
4− Reassemble the unit. The flue box cover gasket and
combustion air inducer gasket should also be
replaced during reassembly.
Service Reminder
Call a qualified service technician if the unit is inoperative.
Before calling, always check the following to be sure
service is required:
1− Be sure electrical disconnect switches are ON.
2− Check room thermostat for proper setting.
3− Replace any blown fuses or reset circuit breakers.
4− Gas valve should be ON.
5− Air filters should not be plugged, limiting air flow.
6− Make sure all access panels are in place.
Repair Parts Listing
When ordering repair parts, include the complete model number and serial number listed on the ETL/C.G.A./CSA rating
plate − e.g. LGA240H2BH1Y.
Gas Heat Section Parts
Heat Exchanger
Combustion Air Assembly
Combustion Air Proving Switch
Burner Assembly
Burner Manifold Assembly
Main Burner Orifices
Flame Roll−out Switches
Auxiliary Limit Controls
Ignition Electrode Assembly
Ignition Lead
Ignition Sensor Assembly
Sensor Lead
Combination Gas Valve
Limit Controls
Cooling Parts
Compressors
Low Pressure Switch
High Pressure Switch
Condenser Fan Motors
Condenser Fan Blades
Condenser Fan Run Capacitors
Freezestats
Low Ambient Pressure Switch
Low Ambient Thermostat
Condenser Fan Mounting Bracket
Fan Grille
Indoor Blower Motors
Blower Wheel
Expansion Valve
Distributor
Crankcase Heaters
Exhaust Fans (Opt.)
Electrical Control Parts
Main Control Panel
Economizer Control Panel (Opt.)
Compressor 2 Control Panel
Compressor 3 and 4 Control Panel
Gas 2 Control Panel
Compressor Contactors
Circuit Breakers (Opt.)
Transformer (Control)
Transformer (Contactor)
Transformer (CAB)
Blower Contactor
Limit, Blower Relay
Heat Relays
Condenser Fan Relays
Capacitor CAB
Relay CAB
Low Ambient Relay
Low Amb. Low Pressure Switches
Disconnect Switch (Opt.)
Blower Motor Overload Relay