Duct Work And Air Conditioning; Air Filter Mounting - Thermo Products Spirit Series Installation, Operation And Service Manual

Duct Work and Air Conditioning

Design and installation of the duct system should follow the current guidelines of the Air
Conditioning Contractors of America (ACCA) or the American Society of Heating,
Refrigeration and Air Conditioning Engineers, Inc. (ASHRAE). Refer to the Residential
Duct Systems, Manual D, from the ACCA, and the ASHRAE Handbook Fundamentals
volume, from ASHRAE, for recommended practices in duct system design and
installation.
All furnaces are tested over a range of external static pressure that simulates the airflow
resistance of the ductwork, fittings, and diffusers connected to the furnace for a typical
(average) duct system. The furnace blower and blower motor have been selected to work
successfully against the following range of duct system resistance.
Recommended range of the duct system external static pressure for all models: 0.2
to 0.5 in. W.G...
Due to the need to maintain an adequate supply of combustion and ventilation air, the
furnace shall not be installed in small room without return air duct system. A return air
duct shall be connected to the furnace return air opening and extend to a location outside
the furnace room.
If the furnace is used in connection with a cooling coil, the coil must be installed in
parallel with, or on the supply side of the furnace to avoid water vapor condensation in
the furnace heat exchanger. If the cooling unit is installed in a parallel flow arrangement,
dampers (or other means used to control airflow) should be provided to prevent chilled air
from entering the furnace. If such a damper is manually operated, it must be equipped
with a means to prevent operation of either unit, unless the damper is placed in either the
full heat or full cool position.
NOTICE: Return air grilles and supply registers in the air distribution system
should never be obstructed.

Air Filter Mounting

On highboy furnaces, it is necessary to cut the return air opening in the side or rear
casing, depending upon the needs of the specific installation. For your convenience, (4)
locator knock-outs have been placed at the proper locations on both the left and right
side casings for the supplied filter rack. The filter rack can be fastened to the furnace with
screws or pop-rivets through the securing flange of the filter rack.
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