PRODUCT DESIGN
This furnace has provisions for the installation of return air filters at the counterflow top return. The furnace will accommodate
the following filter sizes depending on cabinet size:
Optional
Access
Door
Refer to Minimum Filter Area tables to determine filter area requirement. NOTE: Filters can also be installed elsewhere
in the duct system such as a central return.
Counterflow Filters
Return Air
Cabinet Width
"A"
Min
Counterflow Top Return
Filter Area
Qty
2
(in
)
21
600
2
24 1/2
21
800
2
24 1/2
21
1000
2
24 1/2
Filter Size
Dimension "A"
(in)
(in)
13.0
15 X 20 X 1
11.3
18.8
20 X 20 X 1
17.7
24.3
25 X 20 X 1
23.4
13