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24 −Use one screw to resecure the internal flue pipe to the
combustion air inducer.
25 −Use three screws to resecure the vent pipe to the flue
collar. See figure 10.
26 −Reconnect the gas supply piping.
27 −Turn on power and gas supply to the unit.
28 −Set thermostat and check for proper operation.
29 −Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly af-
ter leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
30 −If a leak is detected, shut gas and electricity off and re-
pair leak.
31 −Repeat steps 35 and 36 until no leaks are detected.
32 −Replace front access panels.
Repair Parts List
The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model
number listed on the CSA International nameplate −− Example: G50DF(X)−24A−045−9.
All service must be performed by a
licensed professional installer (or equivalent), service agency, or gas supplier.
Cabinet Parts
Upper access panel
Blower panel
Top cap
Control Panel Parts
Transformer
SureLight
®
integrated control board
Door interlock switch
Circuit breaker
Blower Parts
Blower wheel
Motor
Motor mounting frame
Motor capacitor
Blower housing cut−off plate
Heating Parts
Flame Sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switch
Ignitor
Primary limit control
Flame rollout switches
Secondary limit
Combustion Air Inducer Gaskets
Flue Box Gaskets
Flue Chase Gasket Set
Internal Flue Pipe Assembly
Planned Service
A service technician should check the following items dur-
ing an annual inspection. Power to the unit must be shut off
for safety.
Fresh air grilles and louvers
(on the unit and in the room
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 water.
Vent pipe
− Must be inspected for signs of water, damaged,
cracked or sagging 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 pro-
vide a seal between the return air and the room where the
furnace is installed.
Return air duct
− Must be properly attached and provide
an air seal to the 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 nec-
essary to temporarily shut down the furnace until the items
can be repaired or replaced.
Instruct the homeowners to pay attention to their
furnace.
Situations can arise between annual furnace in-
spections 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.
