Lennox G50DF Series Guide

04/01
*2P0401*
504,324M
*P504324M*
G50DF(X)
SERIES
Litho U.S.A.
504,324M
4/2001
WHAT TO DO IF YOU SMELL GAS:
If the info mation in this manual is not followed
exactly, a fi e o explosion may esult causing
p ope ty damage, pe sonal inju y o loss of
life.
WARNING
DDo not t y to light any appliance.
DDo not touch any elect ical switch; do not use any
phone in you building.
DImmediately call you gas supplie f om a neighbo 's
phone. Follow the gas supplie 's inst uctions.
DIf you cannot each you gas supplie , call the fi e deĆ
pa tment.
DExtinguish any open flames.
GAS FURNACE
Do not sto e o use gasoline o othe flamĆ
mable vapo s and liquids in the vicinity of
this o any othe appliance.
Installation and se vice must be pe fo med by
a qualified installe , se vice agency o the gas
supplie .
E 2001 Lennox Industries Inc.
Dallas, Texas, USA


age 2
G50DF(X) Pa ts Identification
DURALOKTM HEAT
EXCHANGER
ASSEMBLY
LOWER ACCESS
PANEL
BURNERS
BLOWER
MOTOR
GAS
MANIFOLD
CABINET
CONTROL BOX
GAS
VALVE
COMBUSTION AIR
PROVING
(PRESSURE) SWITCH
COMBUSTION AIR
INDUCER
BLOWER ACCESS
PANEL
FLUE
COLLAR
TOP CAP
SURELIGHTt
CONTROL BOARD
FLUE CHASE
FIGURE 1
WARNING
P oduct contains fibe glass wool.
Distu bing the insulation in this p oduct du ing
installation, maintenance, o epai will expose you
to fibe glass wool. B eathing this may cause lung
cance . (Fibe glass wool is known to the State of CalĆ
ifo nia to cause cance .)
Fibe glass wool may also cause espi ato y, skin,
and eye i itation.
To educe exposu e to this substance o fo fu the
info mation, consult mate ial safety data sheets
available f om add ess shown below, o contact you
supe viso .
Lennox Indust ies Inc.
P.O. Box 799900
Dallas, TX 75379-9900
NOTE - This manual must be left with the equipment
user.
WARNING
Do not set the mostat below 60°F (16°C) in heating
mode. Setting the mostat below 60°F (16°C) educes
the numbe of heating cycles. Damage to the unit
may occu that is not cove ed by the wa anty.
WARNING
If ove heating occu s o if gas supply fails to shut off,
shut off the manual gas valve to the appliance befo e
shutting off elect ical supply.
CAUTION
Befo e attempting to pe fo m any se vice o mainteĆ
nance, tu n the elect ical powe to unit OFF at the
disconnect switch.

age 3
WARNING
Do not use this fu nace if any pa t has been unde
wate . Immediately call a qualified se vice technician
to inspect the fu nace and to eplace any pa t of the
cont ol system and any gas cont ol which has been
unde wate .
IMPORTANT
Any additions, changes, o conve sions equi ed in
o de fo the appliance to satisfacto ily meet the apĆ
plication needs must be made by a Lennox se vice
technician using facto y specified and app oved
pa ts.
WARNING
Imp ope installation, adjustment, alte ation, se vice
o maintenance can cause p ope ty damage, pe sonĆ
al inju y o loss of life. Installation and se vice must
be pe fo med by a qualified installe , se vice agency
o the gas supplie .
Impo tant Di ections
1 - Keep the furnace area clear and free of combustible
material, gasoline, and other flammable vapors and
liquids. If it is installed in an insulated area, the furnace
must be kept free of insulating material. Insulating maĆ
terial 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 products near unit
or introduce these products into the combustion air.
These products can cause furnace corrosion.
4 - DO NOT d aw etu n ai f om a oom whe e this fu Ć
nace, o any othe gas appliance (ie., a wate heatĆ
e ), is installed. When return air is drawn from a room,
a negative pressure is created in the room. If a gas apĆ
pliance 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 distributed throughout the house by the
furnace duct system.
WARNING
The blowe doo and flue chase must be secu ely in
place when the blowe and bu ne s a e ope ating.
Gas fumes, which could contain ca bon monoxide,
can be d awn into the living space esulting in pe Ć
sonal inju y o death.
You fu nace 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 pressure
and gas flow rate, adequate combustion air and proper
venting.
WARNING
Ca bon monoxide gas is invisible, odo less, and
toxic.
Exposure to carbon monoxide gas can cause personal injuĆ
ry and even death to all occupants, including pets. Any item
that is powered by, or gives off heat from, a combustion proĆ
cess (including lawn mowers, automobiles, and fireplaces)
has the potential to produce carbon monoxide gas. Because
of this, Lennox ecommends the use of a ca bon monoxĆ
ide detecto in you home, even if you do not own gas
appliances. When propane is used, Lennox also recomĆ
mends use of a propane detector. Reliable detectors are
available at reasonable retail prices. Contact your Lennox
dealer or propane supplier for more details about this inĆ
vestment in your safety.
Your furnace is designed to meet standards set by nationĆ
al agencies. It should operate safely when properly
installed and maintained. However, the unit's perforĆ
mance can be greatly impacted by the individual installaĆ
tion and the operating environment. It is your responsibilĆ
ity to ensure that this appliance is maintained. roper
maintenance is critical for your safety and the satisfactory
operation of the product. Lennox st ongly ecommends
annual inspection and maintenance of this appliance.
Contact your Lennox dealer for an inspection by a qualiĆ
fied service technician.
Lighting Info mation & Ope ation
WARNING
If you do not follow these inst uctions exactly, a fi e
o explosion may esult causing p ope ty damage,
pe sonal inju y o death.
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.

age 4
The gas valve on the G50DF(X) is equipped with either a
gas control knob or lever. Use only your hand to turn the
gas control knob or push the gas lever. Never use tools. If
the knob or lever will not 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.
Placing the G50DF(X) fu nace into ope ation:
G50DF(X) units are equipped with a SureLightt ignition
system. Do not attempt to manually light burners on these
furnaces. Each time the thermostat calls for heat, the burnĆ
ers will automatically light. The ignitor does not get hot
when there is no call for heat on units with the SureLightt
ignition system.
Ope ating the Gas Valve (Figu es 3, 4 and 5)
1 - STOP! Read the safety information at the beginning of
this section.
2 - Set the thermostat to the lowest setting. See figure 2.
3 - Turn off all electrical power to the unit.
THERMOSTATS
FIGURE 2
4 - This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
5 - Remove the lower access panel.
6 - White Rodgers 36E/36F Gas Valve - Switch gas
valve lever to OFF. See figure 3 for the White RodgĆ
ers 36E valve and figure 4 for the White Rodgers
36F valve.
Honeywell VR8205 Gas Valve - Turn knob on gas
valve clockwise to OFF. Do not force. See figure
5.
7 - Wait five 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 instrucĆ
tions. If you do not smell gas go to next step.
8 - White Rodgers 36E/36F Gas Valve - Switch gas valve leĆ
ver to ON. See figure 3 for the White Rodgers 36E
valve and figure 4 for the White Rodgers 36F valve.
Honeywell VR8205 Gas Valve - Turn knob on gas valve
counterclockwise to ON. Do not force.
White Rodge s 36E Se ies Gas Valve
GAS VALVE SHOWN IN OFF POSITION
Gas
Valve
Leve
FIGURE 3
White Rodge s 36F Se ies Gas Valve
GAS VALVE SHOWN IN OFF POSITION
Gas
Valve
Leve
FIGURE 4
ON
OFF
Honeywell VR8205 Se ies Gas Valve
GAS VALVE SHOWN IN OFF POSITION
Gas
Valve Knob
FIGURE 5
9 - Replace the lower access panel.
10 - Turn on all electrical power to to the unit.
11 - Set the thermostat to desired setting.
OTE - 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 instructions
Turning Off Gas to the Unit" and call your service techĆ
nician or gas supplier.
Tu ning Off Gas to the Unit
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 lower access panel.

age 5
4 - White Rodgers 36E/36F Gas Valve - Switch gas
valve lever to OFF.
Honeywell VR8205 Gas Valve - Turn knob on gas
valve clockwise to OFF. Do not force.
5 - Replace the lower access panel.
Filte s
This unit is not equipped with a filter or rack. A field-proĆ
vided, high-velocity filter is required to ensure proper unit
operation.
A filter must be in place any time the unit is operating.
Seasonal Inspections
A qualified service technician should inspect the complete
system each season (heating and cooling). The following
maintenance procedures should only be conducted by a
qualified service technician. Do not attempt to se vice
the unit in any way.
Venting System
WARNING
Asphyxiation Haza d
The exhaust vent fo this fu nace must be secu ely
connected to the fu nace flue colla at all times.
Fo you safety and to fulfill the te ms of the limited
wa anty, a qualified se vice technician must annualĆ
ly inspect this fu nace and its vent system.
Annually (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.
Inspect the furnace venting system to make sure it is in
place, physically sound and without holes, corrosion, or
blockage. The vent connector must be correctly posiĆ
tioned and sloped upward. The vent connector must be
physically sound, without holes or excessive corrosion.
Inspect the furnace return air duct connection. The duct
must be sealed to the furnace and it must terminate outside
the space containing the furnace.
Inspect the physical support of the furnace to guarantee
that it is sound. The support must not sag and must not
have cracks or gaps around the base of the furnace. There
must be a seal between the furnace base and the support.
During a seasonal check, the service technician will inĆ
spect the indoor blower and the burner flames along with
the venting system.
Blowe
Check blower wheel for any debris and clean it, if necesĆ
sary. The blower motor is pre-lubricated for extended bearĆ
ing life. No further lubrication is needed.
Bu ne Flame
CAUTION
To ensu e p ope ope ation, a qualified technician
should annually check the bu ne flame.
Se vice Reminde
Call your Lennox service technician if the unit will not operĆ
ate. Before calling, always check the following to be sure
service 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, which wil limit air flow.
6 - Is gas turned on at meter?
7 - Is manual main shut-off valve open?
Record the model and serial number of the furnace. These
numbers are on the unit nameplate, which is located below
the burners.
Serial Number ________________________________
Model Number ________________________________
Safety P ecautions
If you discove any of the following, shut down you
unit and contact a Lennox deale fo an inspection by a
qualified technician.
DIf 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 unfaĆ
miliar noises.
DIf you smell any unusual odors, your unit may be operatĆ
ing improperly. For example, units can give off unfamilĆ
iar odors if components are required to operate in abĆ
normal conditions.
DLook for visible signs of a malfunctioning unit. Examples
include unusual amounts of condensate on windows inĆ
side your house, visibly burnt components or unusual
dirt or rust accumulations on the vent pipe or in the unit.
DIf you experience headache, nausea, fatigue, or dizziĆ
ness, the cause could be exposure to carbon monoxide
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.

age 6
Planned Se vice
You should expect a service technician to check the followĆ
ing items during an annual inspection. ower to the unit
must be shut off for the service technician's safety.
F esh ai g illes and louve s (on the unit and in the room
where the furnace is installed) - Must be open and unobĆ
structed to provide combustion air.
Bu ne s - Must be inspected for rust, dirt, or signs of water.
Vent pipe - Must be inspected for signs of water, damaged
or sagging pipe, or disconnected joints.
Unit appea ance - Must be inspected for rust, dirt, signs
of water, burnt or damaged wires, or components.
Blowe access doo - Must be properly in place and proĆ
vide a seal between the return air and the room where the
furnace is installed.
Flue chase - Must be properly installed and sealed beĆ
tween the top cap and blower deck during unit operation.
Retu n ai duct - Must be properly attached and provide
an air seal to the unit.
Ope ating pe fo mance - 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.
roblems detected during the inspection may make it necĆ
essary to temporarily shut down the furnace until the items
can be repaired or replaced.
Pay attention to you fu nace. 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 carĆ
bon monoxide gas.