PRODUCT LITERATURE
1996 Lennox Industries Inc.
Dallas, Texas
503,072M
8/99
Supersedes 6/96
G21Q & V
SERIES
GAS FURNACE
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.
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 perĆ
formed by a qualified installer, serĆ
vice agency or the gas supplier.
Litho U.S.A.
WARNING
WHAT TO DO IF YOU SMELL GAS:
D Do not try to light any appliance.
D Extinguish any open flames.
D Do not touch any electrical switch; do not
use any phone in your building.
D Immediately call your gas supplier from a
neighbor's phone. Follow the gas suppliĆ
er's instructions.
D If you cannot reach your gas supplier, call
the fire department.
E1994 Lennox Industries Inc.
G21 (Q & V) Series Parts Arrangement
LIMIT
CONTROL
DIFFERENTIAL
PRESSURE
SWITCH
AIR INTAKE
CONNECTION
AIR VALVE
AND
AIR HOUSING
LOW VOLTAGE
TERMINAL
STRIP
BLOWER
G21Q SERIES
BLOWER MOTOR
DOOR
INTERLOCK SWITCH
GAS VALVE
EXPANSION
TANK
CONTROL
BOX
G21V SERIES
BLOWER MOTOR
FIGURE 1
For Your Safety, Read Before Lighting
WARNING
Do not use this furnace if any part has been underĆ
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.
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.
CAUTION
Before attempting to perform any service or mainteĆ
nance, turn the electrical power to unit OFF at disĆ
connect switch.
WARNING
Do not set the thermostat below 60_F (16_C) when
it is in heating mode. Setting the thermostat below
60_F (16_C) reduces the number of heating cycles.
Damage to the unit may occur that is not covered by
the warranty.
BEFORE LIGHTING smell all around the appliance
area for gas. Be sure to smell next to the floor beĆ
cause some gas is heavier than air and will settle on
the floor.
Page 1
Use only your hand to push in or move the gas control
lever or switch. Never use tools. If the lever or switch
will not push in or move by hand, do not try to repair it,
call a qualified service technician. Force or attempted
repair may result in a fire or explosion.
Important Directions
1. Keep the furnace area clear and free of combustible
material, gasoline, and other flammable vapors and
liquids. If installed in an insulated area, furnace must
be kept 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 ventilatĆ
ing 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 the return air from a room where
another gas appliance (ie., a water heater) is
installed. Even though this furnace draws its comĆ
bustion air from outside of the structure, other gas
appliances that share a utility room may not. When
return air is drawn from a room, a negative pressure
is created in the room. If a 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 the flue gas may result in
incomplete combustion and the formation of carbon
monoxide gas. This toxic gas might then be distribĆ
uted through the house by the furnace duct system.
Your furnace is a gas appliance. It is critical that the gas
supplied to the unit be completely burned to avoid the proĆ
duction of carbon monoxide gas. Complete combustion
of the gas requires, but is not limited to, correct gas presĆ
sure and gas flow rate, adequate combustion, air, and
proper venting.
gas appliances. Reliable detectors are available at reaĆ
sonable retail prices.
Contact your independent 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 operate safely when properly installed
and maintained. However, the unit's performance can be
greatly impacted by the individual installation and the opĆ
erating environment. It is your responsibility to ensure
that this appliance is maintained. Proper maintenance is
critical for your safety and the satisfactory operation of the
product. Lennox strongly recommends annual inĆ
spection and maintenance of this appliance. Contact
your independent Lennox dealer for an inspection by a
qualified service technician.
Unit Operation
This appliance does not have a pilot. It is equipped
with an ignition system which automatically lights
the burner. Do not try to light by hand.
A-Gas Valve Operation
WARNING
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.
Gas Valve Operation for Robertshaw and White
Rodgers Valves (Figures 2 and 4)
ROBERTSHAW 7200 GAS VALVE
GAS VALVE
SELECTOR ARM
IN OFF
POSITION
WARNING
Carbon monoxide gas is invisible, odorless, and
toxic
Exposure to this gas can cause personal injury and even
death to all occupants, including pets. Any item that is
powered by or gives off heat from a combustion process
(including lawn mowers, automobiles, and fireplaces) has
the potential to produce carbon monoxide gas. Because
of this, Lennox recommends the use of a carbon monĆ
oxide detector in your home, even if you do not own
Page 2
WHITE RODGERS
36E GAS VALVE
GAS VALVE
SHOWN
IN OFF
POSITION
FIGURE 2
THERMOSTATS
FIGURE 3
1- Set thermostat to lowest setting. See figure 3.
2- Turn off all electrical power to furnace. See figure 5.
3- This appliance Is equipped with an ignition device
which automatically lights the burner. Do not try to
light the burner by hand.
4- Remove unit access panel.
5- On Robertshaw 7200 gas valve, depress lever on
gas control and move to OFF and release. For
White Rodgers 36E gas valves, move switch to OFF.
Do not force.
6- Wait five (5) minutes to clear out any gas. Smell for
gas, including near the floor. If you then smell gas,
STOP! Immediately call your gas supplier from a
neighbor's phone. Follow the gas supplier's instrucĆ
tions. If you do not smell gas go to next step.
7- On Robertshaw 7200 gas valve, depress lever on
gas control and move to ON and release. For White
Rodgers 36E gas valves, move switch to ON.
8- Replace unit access panel.
9- Turn on all electrical power to unit.
10- Set thermostat to desired setting. See figure 3.
11- If the furnace will not operate, follow the instructions
To Turn Off Gas To Unit" and call your service techniĆ
cian or gas supplier.
B-To Turn Off Gas To Unit
1- Set thermostat to lowest setting.
2- Turn off all electrical power to unit if service is to be
performed.
3- Remove heat section access panel.
4- On Robertshaw 7200 gas valve, depress lever on
gas control and move to OFF and release. For White
Rodgers 36E gas valves, move switch to OFF.
5- Replace unit access panel.
Page 3
GAS PIPING
MANUAL MAIN
SHUT-OFF VALVE
AUTOMATIC
GAS VALVE
GROUND
JOINT
UNION
RIGHT SIDE PIPING
GAS CONNECTOR
DRIP LEG
FIGURE 4
FOR UNIT TO
OPERATE DISCONNECT
SWITCH MUST
BE IN ON" POSITION
TYPICAL
FUSE/DISCONNECT
SWITCH BOX MOUNTED
ON FURNACE
FIGURE 5
Servicing the Filter
Inspect and clean air filters each month. Filters must
be cleaned when dirty to assure proper furnace opĆ
eration and maintain efficiency.
A-Cleaning Reusable Foam Filter
1- Turn off electrical power to furnace.
2- Remove blower access panel. Wait for blower to stop.
3- Remove filter by sliding up and out of channel.
4- Wash filter with water and a mild detergent. For inĆ
creased efficiency, filter media should be sprayed with
Filter Handicoater when dry. Filter Handicoater is RP
products No. 418 and is available as Lennox part No.
P-8-5069. See table 1 for replacement filters.
TABLE 1
G21 Model No.
All Q-40,-60,
Q3-80, Q4-80 and
V3-60, -80 units
Q5-80 and all
Q-100 units: and
V5-80,-100 units
Filter Size
16" x 25"
(406 x 635mm)
20" x 25"
(508 x 635mm)
Filter Part
No.
P-8-7822
P-8-7831
5- Reinstall filter. Slide filter into top channel and drop
into lower channel.
IMPORTANT-Do not replace foam reusable filters
with throw-away type filters.
6- Replace blower access panel.
Lubrication
Motors are prelubricated for extended bearing life; no
further lubrication is required.
Service
At the beginning of each heating season, the system
should be checked as follows:
1- Examine the termination ends of the intake and exĆ
haust lines for obstructions or blockages.
2- Check the intake and exhaust lines for holes, sagĆ
ging or broken isolation hangers. If a sag is found in
either line, raise the line and support it with an isolaĆ
tion hanger. Replace any damaged isolation hangĆ
ers.
3- The return air duct connection should be sealed to
the furnace casing and terminate outside the space
containing the furnace.
4- Check the physical support of the furnace. It should
be sound without sagging, cracks, gaps, etc., around
the base so as to provide a seal between the support
and the base.
5- Check that there is no obvious signs of deterioration
of the furnace.
6- Inspect and clean condensate drain system for free
flow of condensate.
IMPORTANT-If a change in the sound level of the unit
is detected or there is evidence of condensate leakĆ
age around the unit, contact your Lennox service
technician.
Page 4
Service Reminder
Call your Lennox service technician if the unit is inopĆ
erative. Before calling, always check the following to
be sure service is required:
1- Be sure electrical switches are ON.
2- Check the room thermostat for proper setting.
3- Replace any blown fuses or reset circuit breakers.
4- Make sure gas valve is on.
5- Blower access panel is in place.
6- Air filter must be clean.
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.
D 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.
D If you smell any unusual odors, your unit may be operĆ
ating improperly. For example, units can give off unfaĆ
miliar odors if components are required to operate in
abnormal conditions.
D Look for visible signs of a malfunctioning unit. ExamĆ
ples include unusual amounts of condensate on winĆ
dows inside your house, visibly burnt components or
unusual dirt or rust accumulations on the vent pipe or
in the unit.
D If you experience headache, nausea, fatigue, or dizziĆ
ness, the cause could be exposure to carbon monoxĆ
ide gas. This is often misdiagnosed as the flu because
symptoms are similar. If you suffer from flu-like sympĆ
toms that are exaggerated at home, but seem to subĆ
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.
Do not hesitate to contact a qualified service technician as
an investment in your well being.
Planned Service
You should expect a service technician to check the following
items during an annual inspection. 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 open and unobĆ
structed to provide combustion air.
Burners- Must be inspected for rust, dirt, or signs of water.
Ven t pi pe - Must be inspected for dirt, signs of water, damĆ
aged or sagging unsupported pipe, or disconnected joints.
Unit appearance - Must be inspected for rust, dirt, signs of
water, burnt or damaged wires, or components.
Blower access door - Must be properly in place and provide
a seal between the return air and the room where the furnace
is installed.
Return air duct - Must be properly attached and provide an
airtight seal to the unit.
Operating performance - Unit must be observed during opĆ
eration 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 necesĆ
sary to temporarily shut down the furnace until the items can
be repaired or replaced.
Pay attention to your furnace. Situations can arise beĆ
tween annual furnace inspections that may result in unsafe
operation. For instance, items innocently stored next to the
furnace may obstruct the combustion air supply. This could
cause incomplete combustion and the production of carbon
monoxide gas.
Page 5
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