Filter
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WARNING: Turn off the gas and electrical supplies to
the unit before performing any maintenance or service.
Follow the operating instructions on the label attached to
the furnace. A failure to follow this warning could result
in personal injury.
WARNING: Never store anything on, near, or in contact
with the furnace, such as:
1. Spray or aerosol cans, rags, brooms, dust mops,
vacuum cleaners, or other cleaning tools.
2. Soap powders, bleaches, waxes or other cleaning
compounds, plastic or plastic containers, gasoline, kero-
sene, cigarette lighter fluid, dry cleaning fluids, or other
volatile fluids.
3. Paint thinners and other painting compounds, paper
bags or other paper products.
A failure to follow this warning could result in corrosion
of the heat exchanger, fire, personal injury, or death.
The minimum maintenance that should be performed on this
equipment is as follows:
1. Check and clean air filter each month or more frequently if
required. Replace if torn.
2. Check blower motor and wheel for cleanliness and lubrica-
tion each heating and cooling season. Clean and lubricate as
necessary.
3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as necessary.
CAUTION: As with any mechanical equipment, per-
sonal injury can result from sharp metal edges, etc.,
therefore, be careful when removing parts.
A. Air Filter Arrangement
The air filter arrangement may vary depending on the application.
Refer to Table 1 or 2 for filter size information.
TABLE 1—FILTER SIZE INFORMATION FOR DOWN-
FLOW FURNACE (IN.)
FURNACE
CASING WIDTH
FILTER QUANTITY
AND SIZE
FILTER
TYPE
14-3/16 (2) 16 X 20 X 1 Cleanable
17-1/2 (2) 16 X 20 X 1 Cleanable
21 (2) 16 X 20 X 1 Cleanable
24-1/2 (2) 16 X 20 X 1 Cleanable
TABLE 2—FILTER SIZE INFORMATION FOR UPFLOW
FURNACE (IN.)
FURNACE
CASING WIDTH
FILTER QUANTITY AND SIZE
FILTER
TYPE
Side Return Bottom Return
14-3/16 (1) 16 X 25 X 1* (1) 14 X 25 X 1 Cleanable
17-1/2 (1) 16 X 25 X 1* (1) 16 X 25 X 1 Cleanable
21 (1) 16 X 25 X 1 (1) 20 X 25 X 1* Cleanable
24-1/2 (2) 16 X 25 X 1* (1) 24 X 25 X 1 Cleanable
* Factory provided with the furnace. Filters may be field modified by cutting as
required.
WARNING: Never operate unit without a filter or with
filter access door removed. A failure to follow this
warning could result in fire, personal injury, or death.
1. Downflow
Each furnace requires 2 filters which are installed in the
return-air duct. (See Fig. 3.)
To remove filters for cleaning or replacement, proceed as
follows:
a. Disconnect electrical power before removing access
door.
b. Remove blower access door after removing 2 screws.
c. Reach up behind top plate, tilt filters toward center of
return-air plenum, remove filters, and clean as needed.
Replace if torn.
d. Furnaces are equipped with permanent, washable filters.
Clean filters with tap water. Spray water through filter in
opposite direction of airflow.
e. Rinse and let dry. Oiling or coating of filters is not
recommended or required.
f. Reinstall filters.
g. Replace access door and secure with 2 screws.
h. Restore electrical power to furnace.
2. Upflow
Each furnace requires 1 or 2 filters which are installed in the
blower compartment. (See Fig. 4.)
To remove filters for cleaning or replacement, proceed as
follows:
a. Disconnect electrical power before removing access
doors.
Fig. 3—Filter Positions
A88486
RETURN-AIR
PLENUM
AIRFLOW
ACCESS DOOR
INSTALLATION
POSITION
OF FILTERS
—2—