Lennox ML180DF Series User's Information Manual page 7

6- Check the cleanliness of blower assembly and clean
the housing, blower wheel and blower motor if neces­
.
sary
7- Inspect the combustion air inducer and clean if neces­
sary.
8- 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
9- 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
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 ob­
structions and must slope upward away from the fur­
.
nace Check flue pipe, chimney and all connections for
tightness and to make sure there is no blockage. 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 fur­
nace inspection to ensure proper combustion and oper­
ation. 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 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. 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 ad­
.
justable. Verify correct temperature rise.
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