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Turning Off Gas to the Unit
1 − Set the thermostat to the lowest setting.
2 − Turn off all electrical power to the unit if service is to be
performed.
3 − Remove the upper access panel.
4 − Move switch on gas valve to
OFF
. Do not force.
5 − Replace the access panel.
Filters
SL280DFV filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure that the furnace operates prop-
erly. Replacement filters must be rated for high velocity air-
flow. Table 1 lists recommended filter sizes.
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)
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 venting system to make sure it is in
place, physically sound and without holes, corrosion, or
blockage. The vent connector must be correctly posi-
tioned and sloped upward. The vent connector must be
physically sound, without holes or excessive corrosion.
Inspect the furnace return air duct connection. The duct
must be sealed to the furnace and it must terminate outside
the space containing the furnace.
Inspect the physical support of the furnace to guarantee
that it is sound. The support must not sag and must not
have cracks or gaps around the base of the furnace. There
must be a seal between the furnace base and the support.
During a seasonal check, the service technician will in-
spect the indoor blower and the burner flames along with
the venting system.
Blower
Check blower wheel for any debris and clean it, if neces-
sary. The blower motor is pre−lubricated for extended bear-
ing 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.
Service Reminder
Call your Lennox service technician if the unit will not oper-
ate. Before calling, always check the following to be sure
service is required.
1 − Check that electrical disconnect switches are
ON.
2 − Check room thermostat for proper setting.
3 − Replace any blown fuses or reset circuit breakers.
4 − Gas valve should be
ON
.
5 − Air filter should not be plugged, which will limit air flow.
6 − Is gas turned on at meter?
7 − Is manual main shut−off valve open?
Record the model and serial number of the furnace. These
numbers are on the unit nameplate, which is located below
the burners.
Serial Number
________________________________
Model Number ________________________________
