Lennox G24M SERIES Guide

Page 1
WHAT TO DO IF YOU SMELL GAS:
If the information in this manual is not
followed exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
:$51,1*
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.
Do not try to light any appliance.
Do not touch any electrical switch; do not
use any phone in your building.
Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
If you cannot reach your gas supplier, call
the fire department.
Extinguish any open flames.
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE Litho USA
G24M
SERIES
50HZ
GAS FURNACE
503,877M
02/99
Supersedes 9/98
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Page 2
7
6
G24M PARTS IDENTIFICATION
UPFLOW POSITION DOWNFLOW POSITION
1
2
3
4
5
6
7
1
2
3
4
5
1 - COMBUSTION AIR
BLOWER
2 - PRESSURE SWITCH
3- GASVALVE
4 - ROLLOUT SWITCH
(One on each side)
5 - BURNERS
6 - CONTROL BOARD
7- BLOWER
8 - TRANSFORMER
9 - BLOWER DOOR
INTERLOCK SWITCH
8
9
8
9
WARNING
Productcontainsfiberglasswool.Disturbingthe
insulation in this product during installation,
maintenance, or repair will expose you to fiber-
glass wool. Breathing this may cause lung can-
cer. (Fiberglass wool is known to the State of
Californiatocausecancer.)Fiberglasswoolmay
alsocauserespiratory,skin,andeyeirritation.To
reduceexposuretothissubstanceorforfurther
information,consult materialsafety datasheets
available from address shown below, or contact
your supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379-9900
WARNING
If overheating occurs or if gas supply fails to shut
off, shut off the manual gas valve to the appliance
before shutting off electrical supply.
WARNING
Do not use this furnace if any part has been under-
water. Immediately call a qualified service techni-
cian to inspect the furnace and to replace any part
of the control system and any gas control which
has been under water.
CAUTION
Before attempting to perform any service or mainte-
nance, turn the electrical power to unit OFF at discon-
nect switch.
IMPORTANT
Anyadditions,changes,orconversionsrequiredin
orderfortheappliancetosatisfactorilymeettheap-
plication needs must be made by a Lennox service
technician using factory specified and approved
parts.

Page 3
Important Directions
1 - Keep the furnace area clear and free of combustible
material,gasoline,andotherflammablevaporsandliq-
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.
3 - DO NOT store chlorine or fluorine products near unit or
introduce these products into the combustion air.
These products can cause furnace corrosion.
4- DO NOT draw return air from a room where this
furnace, or any other gas appliance (ie., a water
heater),isinstalled.Whenreturnairisdrawnfroma
room, anegativepressure iscreatedin theroom.Ifa
gas appliance is operating in a room with negative
pressure, the flue products can be pulled back down
the vent pipe and into the room. This reverse flow of
thefluegasmayresultinincompletecombustionand
theformationofcarbonmonoxidegas.Thistoxic gas
might then be distributed throughout the house by
the furnace duct system.
Yourfurnaceisagasappliance. It iscriticalthatthegas
suppliedtotheunitbecompletelyburnedtoavoidthepro-
duction of carbon monoxide gas. Complete combustion
of the gas requires, but is not limited to, correct gas pres-
sure and gas flow rate, adequate combustion, air, and
proper venting.
WARNING
Carbon monoxide gas is invisible, odorless, and
toxic.
Exposuretothisgascancausepersonalinjuryandeven
death to all occupants, including pets. Any item that is
powered by or gives off heatfrom a combustionprocess
(including lawn mowers, automobiles, and fireplaces)
has the potential to produce carbon monoxide gas. Be-
cause of this, Lennox recommends the use of a car-
bon monoxide detector in your home, even if you do
not own gas appliances. Reliable detectors are avail-
able at reasonable retail prices. Contact your indepen-
dent Lennox dealer for more details about this invest-
ment in your safety.
Yourfurnaceisdesignedtomeetstandardssetbynation-
alagencies,andtooperatesafelywhenproperlyinstalled
and maintained. However, the unit’s performance can be
greatly impacted by the individual installation and the op-
erating environment. It is your responsibility to ensure
that this appliance is maintained. Proper maintenance is
criticalforyoursafetyandthesatisfactoryoperationofthe
product. Lennox strongly recommends annual in-
spection and maintenance of this appliance. Contact
your independent Lennox dealer for an inspection by a
qualified service technician.
Yourfurnaceisdesignedtomeetstandardssetbynation-
alagencies,andtooperatesafelywhenproperlyinstalled
and maintained. However, the unit’s performance can be
greatly impacted by the individual installation and the op-
erating environment. It is your responsibility to ensure
that this appliance is maintained. Proper maintenance is
criticalforyoursafetyandthesatisfactoryoperationofthe
product. Lennox strongly recommends annual in-
spection and maintenance of this appliance. Contact
your independent Lennox dealer for an inspection by a
qualified service technician.
Lighting Information and Operation
WARNING
If you do notfollow these instructionsexactly, a fire
or explosion may result causing property damage,
personal injury or loss of life.
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.

Page 4
Placing Furnace Into Operation
G24M units are equipped with an electronic ignition system.
Do not attempt to manually light burners on these furnaces.
Each time the thermostat calls for heat, the burner will auto-
matically light.
Use only your hand to turn the gas control knob. Never use
tools. If the knob will not 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.
THERMOSTATS
FIGURE 1
Gas Valve Operation
1- STOP! Read the safety information at the beginning
of this section.
2 - Set the thermostat to lowest setting. See figure 1.
3 - Turn off all electrical power to the unit.
4 - This furnace Is equipped with an ignition device
which automatically lights the burner. Do not try to
light the burner by hand.
5 - Remove the access panel.
6-
White Rodgers 36E Gas Valve - Turn knob on gas valve
180 q either way to OFF. See figure 2.
Honeywell VR8205 Gas Valve - Turn knob on gas valve
clockwise to OFF.Donotforce.Seefigure3.
7 - 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 next step.
WHITE RODGERS 36E SERIES GAS VALVE
GAS VALVE SHOWN IN OFF POSITION
12
2))
FIGURE 2
ON
OFF
HONEYWELL VR8205 SERIES GAS VALVE
GAS VALVE SHOWN IN OFF POSITION
FIGURE 3
8-
White Rodgers 36E Gas Valve - Turn knob on gas
valve 180 q either way to ON.
Honeywell VR8205 Gas Valve - Turn knob on gas
valve counterclockwise to ON. Do not force.
9 - Replace the access panel.
10- Turn on all electrical power to unit.
11- Set the thermostat to desired setting.
NOTE-When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12- If the appliance will not operate, follow the instruc-
tions “Turning Off Gas to Unit” and call your service
technician or gas supplier.
TurningOffGastoUnit
1 - Set the thermostat to the lowest setting.
2 - Turn off all electrical power to the unit if service is to
be performed.
3 - Remove the access panel.
4 - TurnknobonWhiteRodgersgas valve180 q eitherway
to OFF; turn knob on Honeywell valve clockwise to
OFF. Do not force.
5 - Replace the access panel.
Filters
G24Mseriesunitsareequippedwithexternalfilterswhich
should be inspected monthly and replaced when neces-
sary to assure proper furnace operation. See table 1 for
filtersizes.ReplacementfiltersusedwithG24M-40/60/75
units must have a minimum velocity rating of 400 FPM.
Replacement filters used with G24M-100/120/140 units
require a minimum velocity rating of 625 FPM. Figures 4,
5 and 6 show possible filter locations.
TABLE 1
FILTER SIZE
MODEL NUMBER
UPFLOW DOWNFLOW
1FILTER 2FILTERS
G24M-45/60/75 16 in. X 20 in. X 1 in. 16 in. X 20 in. X 1 in.
G24M-100/120/140 20 in. X 20 in. X 1 in. 16 in. X 20 in. X 1 in.

Page 5
UPFLOW FURNACE
BOTTOM RETURN AIR
FIGURE 4
UPFLOW FURNACE
SIDE RETURN AIR
FIGURE 5
DOWNFLOW FURNACE
FILTERS IN PLENUM RACK
FIGURE 6
Blower
Checkandcleanblowerwheelforanydebris.Blowermo-
torisprelubricatedforextendedbearinglife.Nofurtherlu-
brication is needed.
WARNING
Blowerdoormustbe securelyinplacewhen blower
and burners areoperating. Gas fumes,which could
contain carbon monoxide, can be drawn into living
space resulting in personal injury or death.
Burner Flame
The G24M burner flame is not adjustable; however, the
flame should be inspected at the beginning of each heat-
ing season and burners should be cleaned, if necessary.
Burner flame should be blue when burning natural gas,
blue/yellow when burning propane gas.
BURNER FLAME
BURNER
FLAME
HEAT
EXCHANGER
TUBE
VEST
PANEL
FLAME APPEARS BLUE IF
BURNING NAT. GAS; BLUE/
YELLOW FOR PROPANE.
FIGURE 7

Page 6
Venting System Inspection
Annually(beforeheatingseason)inspectfurnaceventing
system, vent cap, heat exchanger and burners for corro-
sion,deterioration,ordepositsofdebris.Removeanyob-
structions.
Contact your Lennox dealer for a periodic unit inspection
by a qualified service technician.
Flame Rollout Safety Switches
Your Lennox furnace is equipped with two flame roll-out
safety switches which shut off the gas supply to the fur-
nace in case of heat exchanger blockage. If the furnace
fails to operate due to the functioning of these safety
switches, DO NOT attempt to place the furnace into op-
eration. Contact a qualified service technician.
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 valve should be ON.
5 - Air filter 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.
Safety Precautions
If you discover any of the following, shut down your
unit, and contact an independent Lennox dealer for
an inspection by a qualified technician.
:
If you repeatedly hear any new or unfamiliar sounds
while your unit is operating, there may be a problem.
For example, poorly performing burners can produce
unfamiliar noises.
:
If you smell any unusualodors, your unit may be oper-
ating improperly. For example, units can give off unfa-
miliar odors if components are required to operate in
abnormal conditions.
:
Look for visible signs of a malfunctioning unit. Exam-
ples include unusual amounts of condensate on win-
dows inside your house, visibly burnt components or
unusual dirt or rust accumulations on the vent pipe or
in the unit.
:
If you experience headache, nausea, fatigue, or dizzi-
ness, the cause could be exposure to carbon monox-
ide gas. This is often misdiagnosed as theflu because
symptoms are similar. If you suffer from flu-like symp-
toms that are exaggerated at home, but seem to sub-
side while you are away from the house, exposure to
carbon monoxide could be the cause.
Your vigilance may pay off in early detection of a problem
before either personal injury or property damage occurs.
Donothesitatetocontactaqualifiedservicetechnicianas
an investment in your well being.
Planned Service
You should expect a service technician to check the fol-
lowing items during an annual inspection. Power to the
unit must be shut off for the service technician’s safety.
Freshairgrillesandlouvers(ontheunitandintheroom
where the furnace is installed) - Must be open and unob-
structed to provide combustion air.
Burners- Must be inspected for rust, dirt, or signs of wa-
ter.
Vent pipe - Must be inspected for signs of water, dam-
aged or sagging pipe, or disconnected joints.
Unit appearance - Must be inspected for rust, dirt, signs
of water, burnt or damaged wires, or components.
Fanaccess door- Must be properly in placeand provide
a seal between the return air and the room where the fur-
nace is installed.
Return air duct - Must be properly attached and provide
an air seal to unit.
Operating performance - Unit must be observed during
operation to monitor proper performance of the unit and
the vent system.
Combustion gases - Flue products must be analyzed
and compared to the unit specifications.
Problems detected during the inspection may make it
necessary to temporarily shut down the furnace until the
items can be repaired or replaced.
Pay attention to your furnace. Situations can arise be-
tween annual furnace inspections that may result in un-
safeoperation.Forinstance,itemsinnocentlystorednext
to the furnace may obstruct the combustion air supply.
Thiscouldcauseincompletecombustionandtheproduc-
tion of carbon monoxide gas.