Lennox G24MCE Guide

Page 1

PRODUCT LITERATURE
1999 Lennox Industries Inc.
Dallas, Texas
WHAT TO DO IF YOU SMELL GAS:
If the information in this manual is not
followe exactly, a fire or explosion
may result causing property amage,
personal injury or loss of life.
WARNING
Do not store or use petrol or other
flammable vapours an liqui s in the
vicinity of this or any other appliance.
Installation an service must be perĆ
forme by a qualifie installer, serĆ
vice agency or the gas supplier.
Do not try to light any appliance.
Do not touch any electrical switch; o not
use any telephone in your buil ing.
Imme iately call your gas supplier from a
neighbor's telephone. Follow the gas supĆ
plier's instructions.
If you cannot reach your gas supplier, call
the local fire briga e.
Extinguish any open flames.
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE Litho USA
G24MCE
SERIES
GAS-FIRED
FURNACE
503,208M
9/99
Supersedes 9/98

Page 2
G24MCE Parts I entification
UPFLOW POSITION DOWNFLOW POSITION
1
2
3
4
5
6
8
1
2
3
4
5
6
8
1 - COMBUSTION AIR FAN
2 - PRESSURE SWITCH
3 - GAS VALVE
4 - CAPILLARY TUBE LIMIT
5 - BURNERS
6 - CONTROL BOARD
7 - HIGH LIMIT
8 - MAIN FAN
7
7
WARNING
This appliance must be earthe .
WARNING
This pro uct contains glass fibre insulation.If inĆ
sulation is isturbe uring installation, mainteĆ
nance or repair, persons may be expose to irritaĆ
tion to the skin, eyes an lungs. Tears in the insulaĆ
tion shoul be repaire straight away.
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 un erĆ
water. Imme iately call a qualifie service techniĆ
cian to inspect the furnace an to replace any part
of the control system an any gas control which
has been un er water.
CAUTION
Before attempting to perform any service or mainteĆ
nance, turn the electrical power to unit OFF at isolaĆ
tor switch.
IMPORTANT
Any a itions, changes, or conversions require in
or er for the appliance to satisfactorily meet the apĆ
plication nee s must be ma e by a Lennox service
technician using factory specifie an approve
parts.

Page 3
Important Directions
1 - Keep the furnace area c ear and free of combustib e
materia , petro , and other f ammab e vapours and iqĆ
uids. If insta ed in an insu ated area, furnace must be
kept free of insu ating materia . Insu ating materia may
be combustib e. Inspect furnace venting system to
make sure it is in p ace, physica y sound, and without
ho es, corrosion, or b ockage. Inspect furnace return
air duct connection to ensure duct is sea ed to the furĆ
nace and terminates outside the space containing the
furnace. Inspect the physica support of the furnace to
guarantee that it is sound without sagging, cracks or
gaps around base and it maintains sea between base
and support.
2 - DO NOT obstruct air f ow to unit. Unit must receive an
unobstructed f ow of combustion and venti ating air.
3 - DO NOT store ch orine or f uorine products near unit or
introduce these products into the combustion air.
These products can cause furnace corrosion.
4- DO NOT raw return air from a room where this
furnace, or any other gas appliance (ie., a water
heater), is installe . When return air is drawn from a
room, a negative pressure is created in the room. If a
gas app iance is operating in a room with negative
pressure, the f ue products can be pu ed back down
the vent pipe and into the room. This reverse f ow of
the f ue gas may resu t in incomp ete combustion and
the formation of carbon monoxide gas. This toxic gas
might then be distributed throughout the house by
the furnace duct system.
Your furnace is a gas appliance. It is critica that the gas
supp ied to the unit be comp ete y burned to avoid the proĆ
duction of carbon monoxide gas. Comp ete combustion
of the gas requires, but is not imited to, correct gas presĆ
sure and gas f ow rate, adequate combustion, air, and
proper venting.
WARNING
Carbon monoxi e gas is invisible, o orless, an
toxic.
Exposure to this gas can cause persona injury and
even death to a occupants, inc uding pets. Any item
that is powered by or gives off heat from a combustion
process (inc uding awn mowers, automobi es, and
firep aces) has the potentia to produce carbon monĆ
oxide gas. Because of this, Lennox recommen s the
use of a carbon monoxi e etector in your home,
even if you o not own gas appliances. Re iab e deĆ
tectors are avai ab e at reasonab e retai prices. ConĆ
tact your independent Lennox dea er for more detai s
about this investment in your safety.
Your furnace is designed to meet standards set by nationĆ
a agencies, and to operate safe y when proper y insta ed
and maintained. However, the unit's performance can be
great y impacted by the individua insta ation and the opĆ
erating environment. It is your responsibi ity to ensure
that this app iance is maintained. Proper maintenance is
critica for your safety and the satisfactory operation of the
product. Lennox strongly recommen s annual inĆ
spection an maintenance of this appliance. Contact
your independent Lennox dea er for an inspection by a
qua ified service technician.

Page 4
Lighting Information an Operation
WARNING
If you o not follow these instructions exactly, a fire
or explosion may result causing property amage,
personal injury or loss of life.
BEFORE LIGHTING sme a around the app iance area
for gas. Be sure to sme next to the f oor because some
gas is heavier than air and wi sett e on the f oor.
Placing Furnace Into Operation
G24MCE units are equipped with an e ectronic ignition sysĆ
tem. Do not attempt to manua y ight burners on these furĆ
naces. Each time the thermostat ca s for heat, the burner
wi automatica y ight.
THERMOSTATS
FIGURE 1
Gas Valve Operation
1 - STOP! Read the safety information at the beginning
of this section.
2 - Set the thermostat to owest setting. See figure 1.
3 - Turn off a e ectrica power to the unit.
4 - This furnace Is equipped with an ignition device
which automatica y ights the burner. Do not try to
ight the burner by hand.
5 - Wait five (5) minutes to c ear out any gas. If you then
sme gas, STOP! Immediate y ca your gas supp ier
from a neighbor's phone. Fo ow the gas supp ier's
instructions. If you do not sme gas go to next step.
6- Turn on a e ectrica power to the unit.
7- Set the thermostat to desired setting.
NOTE-When unit is first started, steps 1 through 7 may
need to be repeated to purge air from gas line.
8- If the app iance sti wi not operate, fo ow the
instructions Turning Off Gas To Unit" and ca your
service technician or gas supp ier.
Turning Off Gas To Unit
1 - Set the thermostat to the owest setting.
2 - Turn off a e ectrica power to the unit if service is to
be performed.
Filters
G24MCE series units are equipped with externa fi ters
which shou d be inspected month y and rep aced when
necessary to assure proper furnace operation. See
tab e 1 for fi ter sizes. Rep acement fi ters used with
G24MCE-40/60/75 units must have a minimum ve ocĆ
ity rating of 2 m/s (400 FPM). Rep acement fi ters used
with G24MCE-100/120/140 units require a minimum
ve ocity rating of 3.2 m/s (625 FPM). Figures 2 and 3
show possib e fi ter ocations when the units are
insta ed in the upf ow position.
TABLE 1
MODEL NO. FILTER SIZE -
mi imeters (inches)
G24MCE-45/60/75 406X508X25
(16 X 20 X 1)
G24MCE-100/120/140 508X508X25
(20 X 20 X 1)
UPFLOW FURNACE
BOTTOM RETURN AIR
FIGURE 2

Page 5
UPFLOW FURNACE
SIDE RETURN AIR
FIGURE 3
Fan
Check and c ean fan whee for any debris. Fan motor is
pre ubricated for extended bearing ife. No further ubricaĆ
tion is needed.
WARNING
Fan oor must be securely in place when fan an
burners are operating. Gas fumes, which coul
contain carbon monoxi e, can be rawn into living
space resulting in personal injury or eath.
Burner Flame
The G24MCE burner f ame is not adjustab e; however,
the f ame shou d be inspected at the beginning of each
heating season and burners shou d be c eaned, if necesĆ
sary. Burner f ame shou d be b ue when burning natura
gas, b ue/ye ow 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 4
Venting System Inspection
Annua y (before heating season) inspect furnace venting
system, vent cap, heat exchanger and burners for corroĆ
sion, deterioration, or deposits of debris. Remove any obĆ
structions.
Contact your Lennox dea er for a periodic unit inspection
by a qua ified gas service engineer.
Capillary Tube Limit Switch
Your Lennox furnace is equipped with a manua yĆreset
capi ary tube imit switch which shuts off the gas supp y to
the furnace in the event of inadequate supp y air (high air
temperature). It is ocated on the vestibu e pane near the
gas va ve. To reset this contro , push the switch on the
face of the contro sideways. If this switch opens again,
consu t a qua ified gas service engineer.
Control Boar Lockouts
Severa types of contro board ockout modes exist on this
furnace. When in one of these modes, the contro board
wi not a ow the furnace to start. The two modes that can
be manua y reset are: a Watchguard ockout mode," and
a Hard ockout mode."
To reset the Watchguard mode," manua y switch the therĆ
mostat from HEAT to OFF and then back to HEAT again.
(Note - This ockout mode wi a so automatica y reset after
a 60 minute ockout period.)
The Hard ockout mode" can be reset by turning the e ecĆ
trica power OFF and then back ON again.
If either of these two ockouts reoccur, or if the origina ockĆ
out cannot be reset, ca a qua ified gas service engineer.

Page 6
Service Remin er
Ca your Lennox service technician if unit is inoperative.
Before ca ing, a ways check the fo owing to be sure serĆ
vice is required.
1 - Check that e ectrica iso ator switches are ON.
2 - Check room thermostat for proper setting.
3 - Rep ace any b own fuses or reset circuit breakers.
4 - Air fi ter shou d not be c ogged imiting air f ow.
5 - Is gas turned on at meter?
6 - Is manua gas cock open?
To keep your Lennox gas heating system in peak
operating condition year after year, contact your
independent Lennox dea er about a p anned service
program.
Safety Precautions
If you iscover any of the following, shut own your
unit, an contact an in epen ent Lennox ealer for
an inspection by a qualifie technician.
SIf you repeated y hear any new or unfami iar sounds
whi e your unit is operating, there may be a prob em.
For examp e, poor y performing burners can produce
unfami iar noises.
SIf you sme any unusua odors, your unit may be operĆ
ating improper y. For examp e, units can give off unfaĆ
mi iar odors if components are required to operate in
abnorma conditions.
SLook for visib e signs of a ma functioning unit. ExamĆ
p es inc ude unusua amounts of condensate on winĆ
dows inside your house, visib y burnt components or
unusua dirt or rust accumu ations on the vent pipe or
in the unit.
SIf you experience headache, nausea, fatigue, or dizziĆ
ness, the cause cou d be exposure to carbon monoxĆ
ide gas. This is often misdiagnosed as the f u because
symptoms are simi ar. If you suffer from f u- ike sympĆ
toms that are exaggerated at home, but seem to subĆ
side whi e you are away from the house, exposure to
carbon monoxide cou d be the cause.
Your vigi ance may pay off in ear y detection of a prob em
before either persona injury or property damage occurs.
Do not hesitate to contact a qua ified service technician as
an investment in your we being.
Planne Service
You shou d expect a service technician to check the fo Ć
owing items during an annua inspection. Power to the
unit must be shut off for the service technician's safety.
Fresh air grilles an louvers (on the unit and in the room
where the furnace is insta ed) - Must be open and unobĆ
structed to provide combustion air.
Burners- Must be inspected for rust, dirt, or signs of waĆ
ter.
Vent pipe - Must be inspected for signs of water, damĆ
aged or sagging pipe, or disconnected joints.
Unit appearance - Must be inspected for rust, dirt, signs
of water, burnt or damaged wires, or components.
Fan access oor - Must be proper y in p ace and provide
a sea between the return air and the room where the furĆ
nace is insta ed.
Return air uct - Must be proper y attached and provide
an air sea to unit.
Operating performance - Unit must be observed during
operation to monitor proper performance of the unit and
the vent system.
Combustion gases - F ue products must be ana yzed
and compared to the unit specifications.
Prob ems detected during the inspection may make it
necessary to temporari y shut down the furnace unti the
items can be repaired or rep aced.
Pay attention to your furnace. Situations can arise beĆ
tween annua furnace inspections that may resu t in unĆ
safe operation. For instance, items innocent y stored next
to the furnace may obstruct the combustion air supp y.
This cou d cause incomp ete combustion and the producĆ
tion of carbon monoxide gas.