Filter
Top Products
IV. FILTER ARRANGEMENT
CAUTION: Never operate unit without a filter or with
blower access panel removed.
Factory-supplied washable framed filters are shipped in blower
compartment. Determine location for filter and relocate filter
retaining wire if necessary. See Table 2 to determine correct filter
size for desired filter location. Table 2 indicates filter size,
location, and quantity shipped with this furnace. See Fig. 2 for
location and size of bottom and side return-air openings.
CAUTION: Air delivery above 1800 CFM requires that
both sides, a combination of 1 side and bottom, or bottom
only of furnace be used for return air.
NOTE: Side return-air openings can ONLY be used in UPFLOW
configurations. Install filter(s) as shown in Fig. 18.
For bottom return-air applications, filter may need to be cut to fit
some furnace widths. Install filter as shown in Fig. 19.
NOTE: Remove and discard bottom closure panel when bottom
inlet is used.
V. BOTTOM CLOSURE PANEL
These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. This panel MUST be in place when side
return air is used.
To remove bottom closure panel, perform following:
1. Tilt or raise furnace and remove 2 screws holding front
filler panel. (See Fig. 20.)
2. Rotate front filler panel downward to release holding tabs.
3. Remove bottom closure panel.
4. Reinstall front filler panel and screws.
TABLE 2—FILTER INFORMATION
FURNACE
CASING
WIDTH (IN.)
FILTER SIZE (IN.)*
FILTER TYPE
FRAMED
Side Return Bottom Return
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
* Filters can be field modified by cutting frame as marked and folding to desired
size. Alternate sizes can be ordered from your distributor or dealer.
† Factory-provided with furnace.
Fig. 18—Filter Installed for Side Inlet
A93045
FILTER
RETAINER
WASHABLE
FILTER
→ Fig. 19—Bottom Filter Arrangement
A96030
WASHABLE
FILTER
FILTER
SUPPORT
FILTER
RETAINER
24
1
⁄2-IN. WIDE
CASINGS ONLY:
CUT AND FOLD
FACTORY-PROVIDED
FILTERS AS SHOWN
TO DESIRED SIZE.
17
1
⁄2-IN. WIDE
CASINGS ONLY:
INSTALL FIELD-SUPPLIED
FILTER FILLER STRIP
UNDER FILTER.
1″
24
1
/
2
″
3″
Fig. 20—Removing Bottom Closure Panel
A93047
BOTTOM
CLOSURE
PANEL
FRONT FILLER
PANEL
—16—