Page 11
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 air in the living space. Use sheet metal screws and
joint tape to seal return air system to furnace.
In platform installations with furnace return, the fur-
nace 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.
For no reason should return and supply air duct sys-
tems ever be connected to or from other heating de-
vices such as a fireplace or stove, etc. Fire, explo-
sion, carbon monoxide poisoning, personal injury
and/or property damage could result.
The unit may be installed three ways in counterflow ap-
plications: on non−combustible flooring, on combustible
flooring using an additive base, or on a reverse−flow cool-
ing coil cabinet.
Do not drag the unit across the floor in
the counterflow position. Floor and furnace flange
damage will result.
Refer to figure 11 for clearances in counterflow applica-
tions.
Counterflow Application Installation Clearances
Top
Bottom
Left Side
Right Side
Top
0
*Front
0
Back
0
Sides
0†
Vent
0
Floor
NC
‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
†Allow proper clearances to accommodate condensate trap and
vent pipe installation.
‡
The furnace may be installed on a combustible wood floor if an op-
tional additive base is installed between the furnace and the com-
bustible floor.
FIGURE 11
Installation on Non−Combustible Flooring (Figure 12)
1 − Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply connec-
tions, 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.
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Width
Front to Rear
Side to Side
in
.
mm
in.
mm
B Cabinet (17.5")
19 − 3/4
502
16 − 5/8
422
C Cabinet (21")
19 − 3/4
502
20−1/8
511
NOTE
− Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See dimension drawing on page 2.
FIGURE 12
SUPPLY AIR
PLENUM
PROPERLY
SIZED FLOOR
OPENING
FURNACE
Installation on Combustible Flooring (Figure 13)
1 − When unit is installed on a combustible floor, a down-
flow combustible flooring base must be installed be-
tween the furnace and the floor. The base must be or-
dered separately. See table 2 for opening size to cut in
floor.
CAUTION
The furnace and combustible flooring base shall not
be installed directly on carpeting, tile, or other com-
bustible material other than wood flooring.
