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- Using heavy gauge perforated steel straps
(plumber's straps") -
Install as shown in figure 12.
Note - Straps must not interfere with plenum or ex
haust piping;
cooling coils and supply and return
air plenums must be supported separately.
Horizontal Application
Unit Suspended in Attic or Crawlspace
Using Heavy Gauge Perforated Steel Straps
(Plumber's Straps")
213/16
(72)
101/4 (260)
Use existing blower deck screws to secure
straps. Also use washers, if required.
11/2 (38)
Inches (mm)
1/2
(13)
SUPPLY
AIR
PLUMBER'S
STRAPS
1/2
(13)
END VIEW
END VIEW
At the unit's top corners, secure each strap to the furnace, positioned
RETURN AIR
OPENING
TOP OF UNIT
SUPPLY AIR
OPENING
TOP OF UNIT
11/2 (38)
1/2
(13)
1/2
(13)
as shown, using at least
two
sheetmetal screws:
maximum screw length - 3/4 in. and minimum screw size - # 10.
Level unit - side to side and end to end.
11/2 (38)
11/2 (38)
FIGURE 12
WARNING
Improper installation of the furnace can result in per
sonal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or the living space. Use screws and joint tape to seal
the return air system to the furnace.
In platform installations with bottom return air, the
furnace should be sealed airtight to the return air ple
num. A door must never be used as a portion of the
return air duct system. The base must provide a
stable support and an airtight seal to the furnace. Al
low absolutely no sagging, cracks, gaps, etc.
The return and supply air duct systems must never
be connected to or from other heating devices such
as a fireplace or stove, etc. Fire, explosion, carbon
monoxide poisoning, personal injury and/or proper
ty damage could result.
Duct System
Use industryapproved standards to size and install the
supply and return air duct system. This will result in a quiet
and lowstatic system that has uniform air distribution.
Supply Air Plenum
Furnaces installed without a cooling coil require the installa
tion of a removable access panel in the supply air duct. The
access panel should be large enough to permit inspection (ei
ther by smoke or reflected light) of the heat exchanger for
leaks after installation . The furnace access panel must al
ways be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.
Return Air Plenum
Return air must not be drawn from a room where this
furnace, or any other gas appliance (ie., a water heat
er), is installed.
When return air is drawn from a room,
a negative pressure is created in the room. If a gas ap
pliance is operating in a room with negative pressure, the
flue products can be pulled back down the vent pipe and
into the room. This reverse flow of the flue gas may result
in incomplete combustion and the formation of carbon
monoxide gas. This toxic gas might then be distributed
throughout the house by the furnace duct system.
In upflow applications, 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 proper and safe operation. Use fiberglass sealing
strips between the plenum and the furnace cabinet to en
sure a tight seal. If a filter is installed, size the return air duct
to fit the filter frame.
In downflow applications, use the following steps when instal
ling return air plenum:
1 - Flange bottom edge of plenum with a hemmed edge.
See
figure 13.
2 - Use fiberglass sealing strips between plenum and the
unit cabinet to ensure a tight seal.
