15
PRODUCT DESIGN
Counterflow Filters
"A"
Min
Return Air
Optional
Access
Door
Return air filters may be installated at the at the counterflow top return. A field supplied center filter support must be provided
by the installer in order to use the top return. The furnace will accommodate the following counterflow top return filter sizes
depending on cabinet size:
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.
Cabinet Width
Filter Area
(in
2
)
Qty
Filter Size
(in)
Dimension "A"
(in)
17 1/2
14.2
21
13.0
24 1/2
11.3
17 1/2
19.7
21
18.8
24 1/2
17.7
17 1/2
25.0
21
24.3
24 1/2
23.4
800
2
20 X 20 X 1
1000
2
25 X 20 X 1
Counterflow Top Return
600
2
15 X 20 X 1
Disposable Minimum Filter Area (in
2
)
[
Based on a 600 ft/min filter face velocity]
*Minimum filter area dictated by heating airflow requirement.
600
800
1000
1200
1400
1600
1800
2000
04 53__X*
207*
207*
24 0
288
---
---
---
---
07 04__X*
---
---
318*
318*
336
384
---
---
09 05__X*
---
---
---
413*
413*
413*
432
480
11 55__X*
---
---
---
437*
437*
437*
432
480
600
800
1000
1200
1400
1600
1800
2000
0704 __X*
0714 __X*
---
---
316*
316*
336
384
---
---
0905 __X*
0915 __X*
---
---
---
409*
409*
409*
432
480
11 55__X*
---
---
---
430*
430*
430*
432
480
In
p
u
t_
_
A
ir
fl
o
w
U PFLOW
COOLING A IRFLOW REQU IREMEN T (CFM)
COUNTER FLOW
COOLING A IRFLOW REQU IREMEN T (CFM)
In
p
u
t
Ai
rf
lo
w
