Lennox G23 Series Owner's manual

G23
SERIES

PRODUCT LITERATURE
W1996 Lennox Industries Inc.
Litho U.S.A.
503,517M
9/98
Supersedes 8/9
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.
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 supplier's instructions.
DIf you cannot reach your gas supplier, call the fire deĆ
partment.
Dallas, Texas
DExtinguish any open flames.
GAS FURNACE
Do not store or use gasoline or other flamĆ
mable vapors and liquids in the vicinity of
this or any other appliance.
Installation and service must be performed by
a qualified installer, service agency or the gas
supplier.

Page 2
G23 Parts Identification
FIGURE 1
DURALOKTM HEAT
EXCHANGER
ASSEMBLY
UPPER ACCESS
PANEL
BURNERS
IGNITION
CONTROL
BLOWER
MOTOR
GAS
MANIFOLD
CABINET
CONTROL BOX
GAS
VALVE
COMBUSTION AIR
PROVING
(PRESSURE) SWITCH
COMBUSTION AIR
BLOWER
BLOWER ACCESS
PANEL
VENT PIPE
CONNECTION
TOP CAP
BLOWER
CONTROL BOARD
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool dust. 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.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379-9900
WARNING
Do not set thermostat below 0_F (1 _C) in heating
mode. Setting thermostat below 0_F (1 _C) reĆ
duces the number of heating cycles. Damage to the
unit may occur that is not covered by the warranty.
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.

Page 3
CAUTION
Before attempting to perform any service or mainteĆ
nance, turn the electrical power to unit OFF at disĆ
connect switch.
WARNING
Do not use this furnace if any part has been under
water. Immediately call a qualified service techniĆ
cian to inspect the furnace and to replace any part
of the control system and any gas control which
has been under water.
IMPORTANT
Any additions, changes, or conversions required in
order for the appliance to satisfactorily meet the apĆ
plication needs must be made by a Lennox service
technician using factory specified and approved
parts.
Important Directions
1- Kee the furnace area clear and free of combustible
material, gasoline, and other flammable va ors and
liquids. If installed in an insulated area, furnace must
be ke t free of insulating material. Insulating material
may be combustible.
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 roducts near unit
or introduce these roducts into the combustion air.
These roducts 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), is installed. When return air is drawn from a
room, a negative ressure is created in the room. If a
gas a liance is o erating in a room with negative
ressure, the flue roducts can be ulled back down
the vent i e and into the room. This reverse flow of
the flue gas may result in incom lete 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 critical that the gas
su lied to the unit be com letely burned to avoid the roĆ
duction of carbon monoxide gas. Com lete combustion
of the gas requires, but is not limited to, correct gas resĆ
sure and gas flow rate, adequate combustion, air, and
ro er venting.
WARNING
Carbon monoxide gas is invisible, odorless, and
toxic.
Ex osure to this gas can cause ersonal injury and even
death to all occu ants, including ets. Any item that is owĆ
ered by or gives off heat from a combustion rocess (inĆ
cluding lawn mowers, automobiles, and fire laces) has the
otential to roduce carbon monoxide gas. Because of
this, Lennox recommends the use of a carbon monoxĆ
ide detector in your home, even if you do not own gas
appliances. Reliable detectors are available at reasonĆ
able retail rices. Contact your inde endent Lennox dealer
for more details about this investment in your safety.
Your furnace is designed to meet standards set by nationĆ
al agencies, and to o erate safely when ro erly installed
and maintained. However, the unit's erformance can be
greatly im acted by the individual installation and the o Ć
erating environment. It is your res onsibility to ensure
that this a liance is maintained. Pro er maintenance is
critical for your safety and the satisfactory o eration of the
roduct. Lennox strongly recommends annual inĆ
spection and maintenance of this appliance. Contact
your inde endent Lennox dealer for an ins ection by a
qualified service technician.
Lighting Information & Operation
WARNING
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or loss of life.
BEFORE LIGHTING smell all around the a liance 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 ush in or turn the gas control
knob. Never use tools. If the knob will not ush in or turn
by hand, do not try to re air it, call a qualified service
technician. Force or attem ted re air may result in a fire
or ex losion.
To place G23 furnace into operation:
G23(X) units are equi ed with a SureLight ignition
system. Do not attem t to manually light burners on
these furnaces. Each time thermostat calls for heat,
the burners will be automatically lit. The ignitor does
not get hot when there is no call for heat on units with
SureLight ignition system.

Page 4
Gas Valve Operation (Figure 3)
1- STOP! Read the safety information at the beginning
of this section.
2- Set thermostat to lowest setting. See figure 2.
THERMOSTATS
FIGURE 2
3- Turn off all electrical ower to a liance.
4- This a liance is equi ed with an ignition device
which automatically lights the burners. Do not try to
light the burners by hand.
5- Remove u er access anel.
6- On Honeywell VR8204 gas valves, turn knob on gas
valve clockwise to OFF. For White Rodgers 36E
gas valves, move switch to OFF. Do not force the
switch. See figure 3.
GAS VALVE SHOWN IN OFF POSITION
FIGURE 3
ON
OFF
HONEYWELL VR8204 SERIES GAS VALVE
WHITE RODGERS
3 E GAS VALVE
GAS VALVE
SHOWN
IN OFF
POSITION
7- Wait fifteen (15) minutes to clear out any gas. If you
then smell gas, STOP! Immediately call your gas
su lier from a neighbor's hone. Follow the gas
su lier's instructions. If you do not smell gas go to
next ste .
8- For Honeywell VR8204 gas valves, turn knob on gas
valve counterclockwise to ON. For White RodgĆ
ers 36E gas valves, move switch to ON. Do not force.
9- Re lace u er access anel.
10- Turn on all electrical ower to unit.
11- Set thermostat to desired setting.
NOTE-When unit is first started, steps 1 through 11 may
need to be repeated to purge air from line.
12- If the a liance still will not o erate, follow the inĆ
structions To Turn Off Gas To Unit" and call your serĆ
vice technician or gas su lier.
Turning Off The Gas To The Unit
1- Set thermostat to lowest setting.
2- Turn off all electrical ower to unit if service is to be
erformed.
3- Remove u er access anel.
4- On Honeywell VR8204 gas valves, turn knob on gas
valve clockwise to OFF. For White Rodgers 36E
gas valves, move switch to OFF. Do not force.
5- Re lace u er access anel.
Filters
A filter must be in lace anytime the unit is in o eration. The
filter may be located in the unit (o tional kit) or installed in a
return air grille. Ask your dealer to show you the filter location.
The filter should be ins ected monthly and cleaned when
necessary to assure ro er furnace o eration.
Filters used inside the G23 series unit are available from LenĆ
nox and must be ordered se arately. These foam filters may
be cleaned for reuse. If re lacement is necessary, order LenĆ
nox art no. 31J81 for 14 X 25 inch filter for G23Q2-50,
Q3-50 and Q2/3-75 units, P-8-7822 for 16 X 25 inch filter for
G23Q3-100 units, and P-8-7831 for 20 X 25 inch filter for
G23Q3/4-100, Q3/4-125, Q4/5-75, Q4/5-100, Q5/6-125 and
Q5/6-150 units. Use the following rocedure to clean filter.
Refer to figure 1.
In-Unit Filter with Bottom Return Air
1- Turn off electric ower to furnace.
2- Remove blower access anel.
3- Remove filter by ressing side filter cli s and ulling filter
u and out. See figure 4.
FIGURE 4
BOTTOM RETURN FILTER INSTALLATION
FURNACE
BASE BOTĆ
TOM
REAR FILTER CLIP
RETURN AIR OPENING
SIDE FILTER CLIPS (2)
FURNACE
FRONT
FURNACE
BACK
4- Clean filter with cold water and a mild soa . Direct
water through filter in the o osite direction of air
flow. Remove all soa residue.
5- Allow filter to dry then s ray with filter handicoater
(P-8-5069), available from your Lennox dealer, rior
to reinstallation.

Page 5
6- Place filter in bottom of blower com artment beneath
rear filter cli . Press down on filter sides. Filter cli s
flex allowing filter to sna into lace.
7- Re lace blower access anel.
WARNING
Blower door must be securely in place when blower
and burners are operating. Gas fumes, which could
contain carbon monoxide, can be drawn into living
space which could cause personal injury or death.
In-Unit Filter with Side Return Air (See Figure 5)
1- Turn off electric ower to furnace.
2- Locate the filter door of the filter rack assembly.
3- Using the filter door ins, ull filter door, with filter atĆ
tached, out of filter rack assembly. Remove filter door
from filter by ulling u on securing tabs.
4- Clean filter with cold water and a mild soa . Direct waĆ
ter through filter in the o osite direction of air flow. AlĆ
low filter to dry then s ray with filter handicoater, availĆ
able from your Lennox dealer, rior to reinstallation.
5- Position filter door on end of filter so that the thumb
tab side of the filter door is away from the furnace.
Check for correct air flow osition. Squeeze thumb
tabs to secure filter to door.
6- Guide filter and filter door into the filter rack
installed on side of furnace. Push door into filter
rack until secure.
FIGURE 5
REMOVING / REPLACING FILTER DOOR
FILTER DOOR FILTER
FILTER DOOR
PIN TAB
TAB
FILTER DOOR
PIN
Seasonal Inspections
A qualified service technician should ins ect the comĆ
lete system each season (heating and cooling). The folĆ
lowing maintenance rocedures should be conducted by
a qualified service technician. Do not attempt to service
the unit in any way.
Venting System
Annually (before heating season) ins ect furnace venting
system, draft hood, vent ca , heat exchanger, and burners
for corrosion, deterioration, or de osits of debris. Remove
any obstructions.
Ins ect furnace venting system to make sure it is in
lace, hysically sound, and without holes, corrosion, or
blockage. Vent connector must be in correct osition,
slo ed u ward and be hysically sound without holes or
excessive corrosion.
Ins ect furnace return air duct connection to ensure duct is
sealed to the furnace and terminates outside the s ace conĆ
taining the furnace.
Ins ect the hysical su ort of the furnace to guarantee that
it is sound without sagging, cracks or ga s around base and
it maintains seal between base and su ort.
During a seasonal check the service technician will ins ect
the indoor blower and the burner flames along with the ventĆ
ing system.
Blower
Check and clean blower wheel for any debris. Blower motor
is re-lubricated for extended bearing life. No further lubricaĆ
tion is needed.
Burner Flame
Burner Flame
Start burner and allow to o erate for a few minutes to esĆ
tablish normal burning conditions. Check burner flame by
observation. Flame should be redominantly blue and
strong in a earance.
CAUTION
To ensure proper operation, a qualified technician
should periodically check the burner flame.

Page 6
Service Reminder
Call your Lennox service technician if unit is ino erative.
Before calling, always check the following to be sure serĆ
vice is required.
1- Check that electrical disconnect switches are ON.
2- Check room thermostat for ro er setting.
3- Re lace any blown fuses or reset circuit breakers.
4- Gas valve should be ON.
5- Air filter should not be lugged limiting air flow.
6- Is gas turned on at meter?
7- Is manual main shut-off valve o en?
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.
DIf you re eatedly hear any new or unfamiliar sounds
while your unit is o erating, there may be a roblem.
For exam le, oorly erforming burners can roduce
unfamiliar noises.
DIf you smell any unusual odors, your unit may be o erĆ
ating im ro erly. For exam le, units can give off unfaĆ
miliar odors if com onents are required to o erate in
abnormal conditions.
DLook for visible signs of a malfunctioning unit. ExamĆ
les include unusual amounts of condensate on winĆ
dows inside your house, visibly burnt com onents or
unusual dirt or rust accumulations on the vent i e or
in the unit.
DIf you ex erience headache, nausea, fatigue, or dizziĆ
ness, the cause could be ex osure to carbon monoxĆ
ide gas. This is often misdiagnosed as the flu because
sym toms are similar. If you suffer from flu-like sym Ć
toms that are exaggerated at home, but seem to subĆ
side while you are away from the house, ex osure to
carbon monoxide could be the cause.
Your vigilance may ay off in early detection of a roblem
before either ersonal injury or ro erty damage occurs.
Do not hesitate to contact a qualified service technician as
an investment in your well being.
Planned Service
You should ex ect a service technician to check the folĆ
lowing items during an annual ins ection. Power to the
unit must be shut off for the service technician's safety.
Fresh air grilles and louvers (on the unit and in the room
where the furnace is installed) - Must be o en and unobĆ
structed to rovide combustion air.
Burners- Must be ins ected for rust, dirt, or signs of water.
Vent pipe - Must be ins ected for signs of water, damĆ
aged or sagging i e, or disconnected joints.
Unit appearance - Must be ins ected for rust, dirt, signs
of water, burnt or damaged wires, or com onents.
Blower access door - Must be ro erly in lace and roĆ
vide a seal between the return air and the room where the
furnace is installed.
Return air duct - Must be ro erly attached and rovide
an air seal to unit.
Operating performance - Unit must be observed during
o eration to monitor ro er erformance of the unit and
the vent system.
Combustion gases - Flue roducts must be analyzed
and com ared to the unit s ecifications.
Problems detected during the ins ection may make it
necessary to tem orarily shut down the furnace until the
items can be re aired or re laced.
Pay attention to your furnace. Situations can arise beĆ
tween annual furnace ins ections that may result in unĆ
safe o eration. For instance, items innocently stored next
to the furnace may obstruct the combustion air su ly.
This could cause incom lete combustion and the roducĆ
tion of carbon monoxide gas.