21
441 01 5003 01
Specifications are subject to change without notice
Figure 20
Optional Duct Standoff
20 x 25 Optional
Filter Rack
Filter
(1 in = 25.4 mm)
Optional Filter Rack Installation: Side Return
Center the filter rack on the side panel, flush with the bottom edge of
the furnace. Mark the fastening holes. Drill the fastening holes in
the side panel and fasten the filter rack in place with sheet metal
screws. See
Figure 21
and
Figure 22
.
Figure 21
Side Return Filter Rack
Filter
25--23--05--1a
Filter Rack End
cap
Figure 22
Filters Installed on Two Sides
25--23--05--3
Filter
Filter
Using Two
Filter Racks
Internal Filter in Bottom- Return Installation
When installing a bottom--mounted filter inside the furnace, install
the filter clips on the edge of the bottom duct opening with the wider
end of the clips toward the blower, as shown in
Figure 23.
Clips
may be obtained from your distributor or fabricated from sheet
metal (
Figure 24
). Insert filter into side clips first and push filter
back until it is fully engaged into back clip.
Figure 23
Bottom Mounted Filter
25--24--18--1
9
″
(23 cm)
Center clip
side--to--side
11
/
16
″
(17 mm)
1
1
/
4
″
(32 mm)
Figure 24
Filter Clip Construction
3
″
(76 mm)
1
1
/
2
″
(38 mm)
26 Ga. Galvanized Steel
FAST part number 1008482
NOTE:
If filters are only suitable for heating application, advise
homeowner that filter size may need to be increased if air
conditioning is added.
Filter Rack with Flanges Downward:
Position the rack with the duct flanges downward so that they
extend below the furnace to attach to ductwork.
The supply duct work should have 90
°
flanges at the connection
end. Screw the duct to the rack flange and not to the furnace bottom.
(Screws in the furnace bottom could lift or penetrate the filter rack to
displace and distort the rack or interfere with filter removal and
insertion in the rack.) The 90
°
duct flange will prevent the duct from
being pushed into the furnace and lifting the rack, which would
cause a duct air leak. Seal the duct flanges to the furnace.
See
Figure 28.
