Thermo Pride Gas/Propane Furnace Induced Draft Highboy/Counterflow/Horizontal MHA1 - Manual (Page 43)

All installations and services must be performed by qualified service personnel.
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D. Return Air Filter
The Return Air Filter(s): Provided with this unit is a permanent type filter. This
filter(s) should be inspected and when dirty, cleaned or replaced, if necessary to
assure proper furnace operation. Follow the cleaning, removal and replacement
procedure below.
Filter Maintenance Procedure:
The filter rack will be located between the return air plenum and the return air
opening of the furnace. See Figure 11 for MHA1/MDA1 series units. Slide dirty
filter out of the filter rack. Clean the filter by vacuuming, rinsing with tap water,
hosing or dipping in an ordinary detergent solution. After cleaning, replace the
completely dry filter in the rack. If the filter has a mesh, the mesh side of the filter
must be towards the furnace.
Figure 11: Filter Location
FILTER REPLACEMENT
Should the filter used require replacement, see Table 2 in Section II, I, of this
manual for minimum filter areas required for the different types of filters available
to ensure an adequate replacement is selected.
MDA1 SERIES
MHA1 SERIES
BLOWER
ACCESS
DOOR
FILTERS
TYPICAL FILTER
LOCATION
FRONT DOOR
SUPPLY AIR
RETURN
AIR
COMBUSTIBLE
FLOOR BASE
SUPPLY AIR
RETURN AIR