Lennox G24-200 Guide

Page 1
503,614M
*P504614M*
07/03
*2P0703*

PRODUCT LITERATURE
E2003 Lennox Industries Inc.
Dallas, Texas
WHAT TO DO IF YOU SMELL GAS:
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.
READ ALL INSTRUCTIONS IN THIS MANUAL
AND RETAIN FOR FUTURE REFERENCE Litho U.S.A.
G24−200
UPFLOW GAS
FURNACE
503,614M
7/2003
Supersedes 1/98
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings ex
actly could result in serious injury
death or property damage.
WARNING
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.
DLeave the building immediately.

Page 2
G24−200 HEAT SECTION AND CABINET
CABINET TOP
HEAT EXCHANGER ASSEMBLY*
LIMIT CONTROL*
LEFT SIDE PANEL* PRESSURE SWITCH*
PRESSURE SWITCH*
FLUE BOX GASKET*
COMBUSTION
AIR BLOWER*
FLUE BOX*
IGNITOR*
SENSOR*
GAS VALVE*
(twostage)
BURNER RETENTION
BRACKET*
BURNER MTG
BRACKET*
FLAME ROLLOUT
SWITCH*
IGNITION CONTROL*
MAKE−UP BOX*
RIGHT SIDE PANEL
HEATING COMPARTMENT ACCESS
PANEL*
BLOWER COMPARTMENT
ACCESS PANEL
CENTER MULLION
REAR PANEL − TOP
REAR PANEL − BOTTOM
FLEXIBLE CONNECTOR
(THIS UNIT CONTAINS TWO HEAT SECTIONS. EACH
HEAT SECTION CONTAINS ONE OF THESE ITEMS.)

Page 3
G24−200 BLOWER SECTION
WHEEL
BLOWER HOUSING
CUTOFF PLATE
BEARING
SHAFT
BLOWER PULLEY
MOTOR PULLEY
(Drive Kit)
VIBRATION ISOLATOR
BASE ASSEMBLY
MOTOR BASE
ADJUSTMENT ARM
MOTOR BASE
LOCATING ROD
DRIVE BELT
(Drive Kit)
MOTOR
(Drive Kit)

Page 4
Safety
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
disconnect 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 fur
ther information, consult material safety data
sheets available from address shown below, or
contact your supervisor.
P.O. Box 799900
Dallas, TX 75379−9900
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.
IMPORTANT
Any additions, changes, or conversions re
quired in order for the appliance to satisfactorily
meet the application needs must be made by a
Lennox service technician using factory speci
fied and approved parts.
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
Danger of explosion and fire. Failure to
follow safety warnings exactly could
result in dangerous operation, serious
injury, 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
SMOKE POTENTIAL
The heat exchanger in this unit could be a source of
smoke on initial firing. Take precautions with re
spect to building occupants and property. Vent ini
tial supply air outside when possible.
WARNING
Danger of explosion. Can cause injury or
death. Do not attempt to light manually.
Unit has a direct spark ignition system.
1 − Keep the furnace area clear and free of combustible
material, gasoline, and other flammable vapors and liq
uids. If installed in an insulated area, furnace must be
kept free of insulating material. Insulating material may
be combustible. Inspect furnace venting system to
make sure it is in place, physically sound, and without
holes, corrosion, or blockage. Inspect furnace return
air duct connection to ensure duct is sealed to the fur
nace and terminates outside the space containing the
furnace. Inspect the physical support of the furnace to
guarantee that it is sound without sagging, cracks or
gaps around base and it maintains seal between base
and support.
2 − DO NOT obstruct air flow to unit. Unit must receive an
unobstructed flow of combustion and ventilating air.

Page 5
3 − DO NOT store chlorine or fluorine products near unit or
introduce these products into the combustion air.
These products can cause furnace corrosion.
BEFORE LIGHTING smell all around the appliance area
for gas. Be sure to smell next to the floor because some
gas is heavier than air and will settle on the floor.
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 techni
cian. Force or attempted repair may result in a fire or ex
plosion.
Lighting Information and Operation
1 − STOP! Read the safety information at the beginning
of this section.
2 − Set thermostat to the lowest setting. See figure 1.
3 − Turn off all electrical power to furnace.
4 − This furnace is equipped with two ignition devices
which automatically light the burners. Do not try to
light burners by hand.
5 − Remove control access panels.
THERMOSTATS
FIGURE 1
WHITE RODGERS 36E TWOSTAGE GAS VALVE
FIGURE 2
GAS VALVE KNOB SHOWN IN OFF" POSITION
LOW HEAT MANIFOLD
PRESSURE FACTORYSET,
NOT FIELDADJUSTABLE.
MANIFOLD
PRESSURE
TAP (SIDE)
HIGH FIRE
ADJUSTMENT
INLET
PRESSURE
TAP (SIDE)
6 − Perform the following to both gas valves: turn knob
on gas valve 180_either way to OFF. Do not force.
7 − Wait five minutes to clear out any gas. If you then
smell gas, STOP! Immediately call your gas suppli
er from your neighbor’s phone. Follow the gas sup
plier’s instructions. If you don’t smell gas go to next
step.
8 − Perform the following to both gas valves: turn knob
on gas valve 180_either way to ON position.
9 − Replace control access panels.
10 − Turn on electrical power to furnace.
11 − Set thermostat to desired setting.
12 − Both combustion air blowers will start. Burners in
both heat sections will light after a 30 second pre
purge.
13 − If furnace does not light first time (gas line not fully
purged) it will attempt up to two more ignitions be
fore locking out.
14 − If lockout occurs, repeat steps 1 through 10.
15 − If the furnace will not operate, follow the instructions
To Turn Off Gas To Unit" and call your service techni
cian or gas supplier.
B−To Turn Off Gas To Unit
1 − Set thermostat to lowest setting.
2 − Turn off all electrical power to furnace if service is to
be performed.
3 − Remove control access panels.
4 − Perform the following to both gas valves: White Rodg
ers 36E series valves: turn knob on gas valve 180_
either way to OFF. Do not force.
Service Reminder
Call your Lennox service technician if unit is inoperative.
Before calling, always check the following to be sure ser
vice is required.
1 − Check that electrical disconnect switches are ON.
2 − Check room thermostat for proper setting.
3 − Replace any blown fuses or reset circuit breakers.
4 − Gas valves should be ON.
5 − Air filters should not be plugged limiting air flow.
6 − Is gas turned on at meter?
7 − Is manual main shutoff valve open?
To keep your Lennox gas heating system in peak operat
ing condition year after year, contact your independent
Lennox dealer about a planned service program.

Page 6
Service
A qualified service technician should inspect the com
plete system each season (heating and cooling). The fol
lowing maintenance procedures should only be con
ducted by a qualified service technician. Do not attempt
to service the unit in any way.
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could re
sult in dangerous operation, serious injury, death
or property damage.
Improper servicing could result in dangerous op
eration, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior to dis
connecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
Venting System
WARNING
Asphyxiation Hazard
The exhaust vent for this furnace must be securely
connected to the furnace flue collar at all times.
For your safety and to fulfill the terms of the limited
warranty, a qualified service technician must annu
ally inspect this furnace and its vent system.
Annually (before heating season) inspect furnace venting
system, vent cap, heat exchanger, and burners for corro
sion, deterioration, or deposits of debris. Remove any ob
structions.
Inspect the furnace for obvious signs of deterioration.
Inspect the furnace venting system to make sure it is in
place, physically sound, and without holes, corrosion, or
blockage.
Vent pipe must be clear and free of obstructions and must
slope upward away from the furnace.
Inspect the furnace return air duct connection to ensure
duct is sealed to the furnace and terminates outside the
space containing the furnace.
During a seasonal check the service technician will in
spect the indoor blower, burner flames and electrical con
nections along with the venting system.
Burner Flame
CAUTION
To ensure proper operation, a qualified technician
should annually check the burner flame.
Blowers
Check the blower wheels for debris and clean if neces
sary. The blower motors are prelubricated for extended
bearing life. No further lubrication is needed.
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), Chev
ron 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.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal in
jury or death.
Filters
All G24−200 filters are installed external to the unit. Filters
should be inspected monthly and cleaned or replaced
when necessary to assure proper furnace operation. If
optional filter box is used, see figures 3 or 4 for replace
ment directions. The filter box contains four 16x25 inch
(406mmx635mm) filters.
NOTE − Replacement filters must be U.L.C. certified or
equivalent for use in Canada.
Flame Rollout Safety Switches
Your Lennox furnace is equipped with two sets of flame
rollout safety switches (one in each heat section). Each
switch shuts off the gas supply to the heat section it con
trols when blockage occurs to its heat exchanger. If the
furnace fails to operate due to the functioning of one or
both of these safety switches, DO NOT attempt to place
the furnace into operation. Contact a qualified service
technician.

Page 7
FIGURE 3
REAR RETURN AIR FILTER BOX
With Top or Side Filter access
SIDE
FILTER
ACCESS
PANEL
FOUR FILTERS
(Filters may also be installed
through top of filter box)
TOP
FILTER
ACCESS
PANEL
G24−200
UNIT
FILTER
BOX
FIGURE 4
FRONT FILTER
ACCESS PANEL
G24−200
UNIT
FOUR FILTERS
(Filters may also
be installed
through side of
filter box)
SIDE FILTER
ACCESS PANEL
BOTTOM RETURN AIR FILTER BOX
With Front or Side Filter access
Burners (Both heat sections)
Inspect the burners and burner flame at the beginning of
each heating season. If necessary, clean the burners as
indicated below:
1 − Turn off the electrical and gas supply to the furnace.
2 − Remove the burner box top.
3 − Remove the burner retaining bracket.
4 − Remove the burners.
5 − Clean the inside of each burner with a bottle brush as
shown in figure 5.
CLEANING BURNERS
BOTTLE
BRUSH
BURNER
FIGURE 5
6 − Check the electrode gap using appropriately sized
twist drills or feeler gauges. Gap should be between
0.110 and 0.140 inches (2.79 to 3.56mm).
7 − Replace the burners and the burner retaining brack
et. Make sure that the burners are properly seated in
their slots in the tray and that each burner and man
ifold orifice is aligned properly.
8 − Reinstall the burner box top.
9 − Carefully check all piping connections (factory and field)
for gas leaks. Use a leak detecting solution or other pre
ferred means.
IMPORTANT
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 other sources of igni
tion to check for gas leaks.
10 − Restore electrical power and gas supply to the furnace.
Follow lighting instructions on the front of the unit. Check
the appearance of the burner flame, burner pressure,
gas flow, and temperature rise. If necessary, make ad
justments. See the other unit adjustments section.

Page 8
Flue And Chimney
Check the flue pipe, chimney and all connections for tight
ness and to make sure there is no blockage.
Heat Exchangers (Both)
Periodically inspect the heat exchanger tubes and flue box
for corrosion. If necessary, clean as indicated below:
1 − Turn off the electrical and gas supply to the furnace.
2 − Disconnect the wiring to the combustion air fan.
3 − Remove the screws securing the flue box to the fur
nace. Clean the flue box with a wire brush (brass
bristle brush recommended).
4 − Disconnect the gas supply piping and the ignitor and
sensor wires. Remove the burner assembly from the
furnace.
5 − Pull a largebore wire brush (brassbristle brush recom
mended) through each heat exchanger tube to clean.
6 − Reinstall the flue box using a new gasket.
7 − Reconnect the combustion air fan wiring.
8 − Reinstall the burner box, ignitor and sensor wires and
the gas supply piping.
9 − Follow step 10 in the burners section above.
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating).
3 − Check ampdraw on blower motor.
Motor service factor amps
Nameplate __________Actual__________
Repair Parts List
The following repair parts are available through independent Lennox dealers. When ordering parts, include the complete
furnace model number listed on the CSA international. rating plate  Example: G24−200. Refer to page 4 and 5 for parts
identification.
Cabinet Parts Electrical Parts Heating Parts Blower Parts
Front louver door (2)Transformer(s) Heat exchanger (2) Wheel (2)
Blower access panel (2) Ignition control board (2) Main burners Motor
Cabinet cap Door interlock (2) Main burner orifices Cutoff plate (2)
Cabinet toprear Ignition cable (2) Gas manifold/burner
box assembly (2)
Shaft
Cabinet bottomrear Ignitor (2) Gas valve (2) Motor pulley
Flue adapter (2) Flame sensor (2) Flue box (2) Wheel pulley
Rollout switch (2) Combustion air blower (2) Belt
Primary limit (2) Flexible gas connector Bearing (2)
Pressure switch (2) Vibration isolators (4)
Blower timing control board Locating rods (2)
Accessory relay
Blower operation relays
Contactor
Combustion air blower
operation relays