507581-04Page 14 of 60 Issue 2128
Return Air - Horizontal Applications
Return air may be brought in only through the end of a
furnace installed in the horizontal position. The furnace
is equipped with a removable bottom panel to facilitate
installation. See Figure 16.
Filters
This unit is not equipped with a lter or rack. A eld provided
lter is required for the unit to operate properly. Table 1 lists
recommended lter sizes.
A lter must be in place whenever the unit is operating.
Table 1. Filter Sizes
Furnace Cabinet
Width
Filter Size
Side Return Bottom Return
17-1/2”
16 x 25 x 1
16 x 25 x 1
21” 20 x 25 x 1
24-1/2” 24 x 25 x 1
Duct System
Use industry approved standards to size and install the
supply and return air duct system. This will result in a quiet
and low-static system that has uniform air distribution.
NOTE: This furnace is not certied for operation in heating
mode (indoor blower operating at selected heating speed)
with an external static pressure which exceeds 0.8 inches
w.c. Operation at these conditions may result in improper
limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
(by reected light) of the heat exchanger for leaks after the
furnace is installed. The furnace access panel must always
be in place when the furnace is operating and it must not
allow leaks into the supply air duct system.
Return Air Plenum
NOTE: Return air must not be drawn from a room where
this furnace, or any other gas fueled appliance (i.e., water
heater), or carbon monoxide producing device (i.e., wood
replace) is installed.
When return air is drawn from a room, a negative pressure
is created in the room. If a gas appliance is operating in
a room with negative pressure, the ue products can be
pulled back down the vent pipe and into the room. This
reverse ow of the ue gas may result in incomplete
combustion and the formation of carbon monoxide gas.
This raw gas or toxic fumes might then be distributed
throughout the house by the furnace duct system.
Return air can be brought in through the bottom or either
side of the furnace. If a furnace with bottom return air is
installed on a platform, make an airtight seal between the
bottom of the furnace and the platform to ensure that the
unit operates properly and safely. Use berglass sealing
strips, caulking, or equivalent sealing method between the
plenum and the furnace cabinet to ensure a tight seal. If
a lter is installed, size the return air duct to t the lter
frame.
Pipe & Fittings Specications
All pipe, ttings, primer and solvent cement must conform
with American National Standard Institute and the American
Society for Testing and Materials (ANSI/ASTM) standards.
The solvent shall be free owing and contain no lumps,
undissolved particles or any foreign matter that adversely
affects the joint strength or chemical resistance of the
cement. The cement shall show no gelation, stratication,
or separation that cannot be removed by stirring. Refer to
Table 2 for approved piping and tting materials.
Solvent cements for plastic pipe are ammable liquids
and should be kept away from all sources of ignition.
Do not use excessive amounts of solvent cement when
making joints. Good ventilation should be maintained to
reduce re hazard and to minimize breathing of solvent
vapors. Avoid contact of cement with skin and eyes.
CAUTION
Joint Cementing Procedure
Use PVC primer and solvent cement or ABS solvent
cement meeting ASTM specications, refer to Table 2.
As an alternate, use all purpose cement, to bond ABS,
PVC, or CPVC pipe when using ttings and pipe made of
the same materials. Use transition solvent cement when
bonding ABS to either PVC or CPVC.
Low temperature solvent cement is recommended during
cooler weather. Metal or plastic strapping may be used for
vent pipe hangers. Uniformly apply a liberal coat of PVC
primer for PVC or use a clean dry cloth for ABS to clean
inside socket surface of tting and male end of pipe to
depth of tting socket.
Canadian Applications Only
Pipe, ttings, primer and solvent cement used to vent
(exhaust) this appliance must be certied to ULC S636 and
supplied by a single manufacturer as part of an approved
vent (exhaust) system. When bonding the vent system to
the furnace, use ULC S636 approved One-Step Transition
Cement to bond the pipe to the ue collar, or to bond
the 90° elbow or reducing 90° elbow to the ue collar. In
addition, the rst three feet of vent pipe from the furnace
ue collar must be accessible for inspection.
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