Thermo Products THV1M119A960SA, Installation And Operation Manual

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E. Air Filter Mounted External to Furnace:
On highboy furnaces, it is necessary to cut the return air opening in the side, rear casing or base,
depending upon the needs of the specific installation. The filter rack provided with the furnace, refer to
Fig. 9, will serve as a template to scribe a mark for the return air opening on the casing. Place the filter
rack on a side casing approximately one inch up from the bottom of the furnace and centered from side to
side. Place the securing flange against the casing when locating the return air opening. For your
convenience, (4) locator knockouts have been placed at the proper locations on both the left and right
side casings.
PLEASE NOTE: While scribing the return air opening, the filter rack can be held in position by tape or
similar temporary means. Position the open end of the filter rack so as to provide access for filter
replacement. Once the filter rack is positioned correctly, scribe a line along the inside of the securing
flange on three of the sides. To scribe a line on the fourth side (the open end), use the open-end support
as a guide.
Remove the filter rack and cut the return air opening in the casing. 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. 9).
Fig. 9: A typical filter rack and dimensions for the THV1M119A* furnace.
: Failure to comply with minimum filter installation requirements may affect the
performance and/or void the warranty on this unit.