508189-01
Issue 2116
Page 28 of 42
6.
Check the cleanliness of blower assembly and
clean the housing, blower wheel and blower motor if
necessary. The blower motors are prelubricated for
extended bearing life. No further lubrication is needed.
7.
Inspect the combustion air inducer and clean if
necessary.
8.
Evaluate the heat exchanger integrity by inspecting
the heat exchanger per the AHRI heat exchanger
inspection procedure. This procedure can be viewed
at www.ahrinet.org
9.
Ensure sufficient combustion air is available to the
furnace. Fresh air grilles and louvers (on the unit and
in the room where the furnace is installed) must be
properly sized, open and unobstructed to provide
combustion air.
10.
Inspect the furnace venting system to make sure it is in
place, structurally sound, and without holes, corrosion,
or blockage. Vent system must be free and clear of
obstructions and must slope upward away from the
furnace. Vent system should be installed per the
National Fuel Gas Code.
11.
Inspect the furnace return air duct connection to ensure
the duct is sealed to the furnace. Check for air leaks
on supply and return ducts and seal where necessary.
12.
Check the condition of the furnace cabinet insulation
and repair if necessary.
13.
Perform a complete combustion analysis during the
furnace inspection to ensure proper combustion
and operation. Consult Service Literature for proper
combustion values.
14.
Verify operation of CO detectors and replace batteries
as required.
Perform a general system test. Turn on the furnace to
check operating functions such as the start-up and shut-off
operation.
1.
Check the operation of the ignition system, inspect
and clean flame sensor. Check microamps before and
after. Check controls and safety devices (gas valve,
flame sensor, temperature limits). Consult Service
Manual for proper operating range. Thermal Limits
should be checked by restricting airflow and not
disconnecting the indoor blower. For additional details,
please see Service and Application Note H049.
2.
Verify that system total static pressure and airflow
settings are within specific operating parameters.
3.
Clock gas meter to ensure that the unit is operating
at the specified firing rate. Check the supply pressure
and the manifold pressure. On two-stage gas furnaces
check the manifold pressure on high fire and low fire.
If manifold pressure adjustment is necessary, consult
the Service Literature for unit specific information
on adjusting gas pressure. Not all gas valves are
adjustable. Verify correct temperature rise.
Figure 18. Burner, Combustion Air Inducer Assembly & Heat Exchanger Removal
gasket
collector box
orifice plate
internal flue pipe
pressure switch
combustion air inducer
burners
manifold and gas valve
retention rings
cross over
heat exchanger
flue chase
gasket
rollout switch
ignitor
sensor
