Filter
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13
Now the filter rack can be anchored to the furnace with screws or pop-rivets through the securing flange
of the filter rack.
Connect the return air plenum to the filter rack and slide the filter into place. Dimensions for adapting the
return air plenum to the filter rack are provided (See Fig. 6).
Note: Filter rack and condensate drain must be on separate sides of the furnace.
Fig-6 A typical filter rack and dimensions for the OHC furnace.
: Failure to comply with minimum filter installation requirements may affect the
performance and/or void the warranty on this unit.
If a method other than Thermo Pride filter racks is selected for retention of the filter and/or use of a
different filter type is desired, refer to Table 2 below for minimum sizing guidelines for selecting filter for
the unit.
Filter Type
Maximum
Air Velocity
(ft/min)
Model Number
OHC*
*Thermo Products
Supplied
Permanent
600
384 in
2
Standard
Permanent
500
461 in
2
Disposable 300
768 in
2
Table 2: Minimum Required Filter Area (in square inches)
* The Thermo Products supplied filter can be cut to size to fit other filter retention systems as
long as the minimum size requirement is met.