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6- Evaluate the heat exchanger integrity by inspecting the
heat exchanger per the AHRI heat exchanger inspec
tion procedure. This procedure can be viewed at
www.ahrinet.org. See “Induced-draft Furnace Heat Ex
changer Inspection Procedure”.
7- Ensure sufficient combustion air is available to the fur
nace. 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
.
8- 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 ob
structions and must slope upward away from the fur
nace
.
Vent system should be installed per the National
Fuel Gas Code
9- 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
.
10- Check the condition of the furnace cabinet insulation
and repair if necessary.
11- Perform a complete combustion analysis during the fur
nace inspection to ensure proper combustion and oper
ation. Consult Service Literature for proper combustion
values.
12- Verify operation of smoke detectors and 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 dis
connecting the indoor blower. For additional details,
please see Service and Application Note H049.
2 - Verify that system total static pressure and airflow set
tings 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.
If manifold pressure ad
justment is necessary, consult the Service Literat
ure for unit specific information on adjusting gas
pressure. Not all gas valves are adjustable
.
Verify
correct temperature rise.
