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Units with 1/2 or 3/4 HP Blower Motor
Figure 7.
The blower access panel must be securely in place
when the blower and burners are operating. Gas fumes,
which could contain carbon monoxide, can be drawn
into living space resulting in personal injury or death.
Downflow Installation
Downflow unit installs in three ways: on non-combustible
flooring, on combustible flooring using a downflow
combustible flooring base, or on a reverse-flow cooling
cabinet. Do not drag the unit across the floor.
Installation on Non-Combustible Flooring
(Figure 8)
1.
Cut floor opening keeping in mind clearances listed
on unit rating plate. Also keep in mind gas supply
connections, electrical supply, flue and air intake
connections and sufficient installation and servicing
clearances. See Table 1 for correct floor opening size.
2.
Flange warm air plenum and lower the plenum into the
opening.
3.
Set the unit over the plenum and seal the plenum to
the unit.
4.
Ensure that the seal is adequate.
UNIT
OPENING
Figure 8.
508145-01G / 31-5000660
RIGID LEG
remove shipping bolt and washer
WARNING
SUPPLY AIR
PLENUM
Cabinet
Width
A (14-1/2")
B (17-1/2")
NOTE - Floor opening dimensions listed are 1/4 inch (6 mm)
larger than the unit opening. See unit dimensions on Page
2.
Table 1. Non-Combustible Floor Opening Size
Installation on Combustible Flooring
(Figure 9)
1. When unit is installed on a combustible floor, a
downflow combustible flooring base must be installed
between the furnace and the floor. The base must be
ordered separately. See Table 2 for opening size to
cut in floor.
2.
After opening is cut, set combustible flooring base into
opening.
3.
Check sealing strips on combustible flooring base to
make sure they are properly glued and positioned.
4.
Lower supply air plenum into downflow combustible
flooring base until plenum flanges seal against the
strips.
NOTE: Be careful not to damage sealing strips. Check
for a tight seal.
5.
Set the furnace over the plenum.
6.
Ensure that the seal between the furnace and plenum
is adequate.
The furnace and downflow combustible flooring base
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
UNIT
PROPERLY
SIZED FLOOR
OPENING
Issue 2220
Front to Rear
Side to Side
in
mm
in
19-3/4
502
13-1/4
19-3/4
502
16-1/4
IMPORTANT
SUPPLY AIR PLENUM
DOWNFLOW
COMBUSTIBLE
FLOORING BASE
Figure 9.
mm
337
413
Page 9 of 38
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