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DESCRIPTION OF COMPONENTS
The descriptions below are various functional components
that affect the operation and shutting down of this furnace.
Some of these components and their locations are shown
in Figures 40 and 41 (page 51). If any component of the
furnace must be replaced, use only factory authorized
replacement parts specifi ed in the Replacement Parts
List provided online.
Blower Limit Switch
The Blower switch prevents furnace operation when blower
is not operational.
Condensate Drain Switch
The Condensate Drain Switch will shut down the furnace
if the condensate drain from the Collector Pan becomes
clogged.
Flame Sensor
The fl ame sensor verifi es when a fl ame has carried over
from the igniter to the opposite end burner. If no fl ame is
detected, the furnace will shut down within 4 seconds.
Flame Roll-Out Switch
The fl ame roll-out switch verifi es that the burner fl ames
are drawn into the heat exchanger tubes. If the burner
fl ames are not properly drawn into the heat exchanger, the
fl ame roll-out switch will close the gas valve and initiate
the shutdown cycle.
Gas Valve
The gas valve controls the fl ow of gas to the burners.
When the gas valve is energized it automatically opens
and regulates the gas pressure in the manifold.
Inducer Assembly
The inducer assembly vents products of combustion to
the outside.
Pressure Switch
The pressure switch verifi es that the inducer is drawing
the combustion gases through the heat exchanger. If
the fl ame is not properly drawn into the heat exchanger
tube, the rollout switch or the fl ame sensor will shut the
furnace down.
Supply Air Limit Switch
The supply air limit switch prevents the air temperature
leaving the furnace from exceeding the maximum
allowable outlet air temperature.
30
MAINTENANCE
WARNING:
These maintenance instructions are primarily
intended to assist qualified technicians
experienced in the proper maintenance and
operation of this appliance.
Proper maintenance is most important to achieve the best
performance from a furnace. Follow these instructions for
years of safe, trouble free operation.
• Always reinstall the doors on the furnace after servicing
or cleaning/changing the fi lters. Do not operate the
furnace without all doors and covers in place.
• Verify that the thermostat is properly installed and is not
affected by drafts or heat from lamps or other appliances.
• To achieve the best performance and minimize
equipment failure it is recommended that a yearly
maintenance checkup be performed. At a minimum,
this check should include the following items:
Air Filter(s)
WARNING:
Never operate the furnace without a fi lter in
place. Dust and lint in the return air can build
up on internal components, resulting in loss
of effi ciency, equipment damage, and possible
fi re.
Note: Air fi lter(s) are not supplied with the furnace as
shipped from the factory. The installer must provide a
high velocity fi lter and rack for a fi lter in the return air
duct adjacent to the furnace, or in a return air grill to the
furnace. It is recommended that fi lters be cleaned or
replaced monthly. New or newly renovated homes may
require more frequent changing until the construction
dust has minimized.
Filters designed to remove smaller particles such as
pollen, may require additional maintenance. Filters for
side return and bottom return applications are available
from most local distributors.
Blower Compartment
Dirt and lint can create excessive loads on the motor
resulting in higher than normal operating temperatures
and shortened service life. It is recommended that the
blower compartment be cleaned of dirt or lint that may
have accumulated in the compartment or on the blower
and motor as part of the annual inspection.
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