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Filters
All ML180UHE filters are installed external to the unit. Fil-
ters should be inspected monthly. Clean or replace the fil-
ters when necessary to ensure proper furnace operation.
Replacement filters must be rated for high velocity airflow.
Table 1 lists recommended filter sizes.
A filter must be in place when the unit is operating.
TABLE 1
Furnace
Cabinet Width
Filter Size
Side Return
Bottom Return
14−1/2"
16 X 25 X 1 (1)
14 X 25 X 1 (1)
17−1/2"
16 X 25 X 1 (1)
16 X 25 X 1 (1)
21"
16 X 25 X 1 (1)
20 X 25 X 1 (1)
24−1/2"
16 X 25 X 1 (2)
24 X 25 X 1 (1)
Maintenance
A licensed professional service technician (or equivalent)
should inspect the complete system each season (heating
and cooling). The following maintenance procedures
should only be conducted by a licensed professional ser-
vice technician (or equivalent).
Do not attempt to service
the unit in any way.
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.
Improper servicing could result in dangerous opera-
tion, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior to dis-
connecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
Venting System
WARNING
Asphyxiation Hazard
The exhaust vent for this furnace must be leak−free
and must be securely connected to the furnace flue
collar at all times.
For your safety and to fulfill the terms of the limited
warranty, a licensed professional service technician
(or equivalent) must annually inspect this furnace
and its vent system.
Annually (before heating season) inspect furnace venting
system, vent cap, heat exchanger, and burners for corro-
sion, deterioration, or deposits of debris. Remove any ob-
structions.
Inspect the furnace for obvious signs of deterioration.
Inspect the furnace venting system to make sure it is in
place, physically sound, and without holes, corrosion, or
blockage.
Vent pipe must be clear and free of obstructions and must
slope upward away from the furnace.
Inspect the furnace return air duct connection to ensure
duct is sealed to the furnace and terminates outside the
space containing the furnace.
Inspect the physical support of the furnace to guarantee
that it is sound without sagging, cracks or gaps around
base and it maintains seal between base and support.
During a seasonal check the service technician will con-
duct a combustion analysis. The technician will also in-
spect the indoor blower, burner flames, electrical connec-
tions and the venting system.
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal inju-
ry or death.
Burner Flame
CAUTION
To ensure proper operation, a licensed professional
service technician (or equivalent) should check the
burner flame and conduct a combustion analysis
annually.
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating).
3 − Check amp−draw on the blower motor with blower ac-
cess panel in place.
Motor Nameplate__________Actual__________
