507332-02G / 31-5000663
Page 9 of 35
Issue 2209
Figure 7.
Units with 1/2 HP & 3/4 HP
Blower Motor
Downflow Applications
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or
alcove installations are shown in Figure 8.
Figure 8.
Downflow Application Installation
Clearances
Type of Vent
Connector
Type C
Type B
1
Top
1 in. (25 mm)
1 in. (25 mm)
*Front
2-1/4 in. (57 mm)
2-1/4 in. (57 mm)
Back
0
0
Sides
0†
0
Vent
6 in. (152 mm)
1 in. (25 mm)
Floor
0‡
0‡
* Front clearance in alcove installation must be 24 in. (610
mm). Maintain a minimum of 24 in. (610 mm) for front service
access.
‡ For installation on a combustible floor, do not install the
furnace directly on carpeting, tile or other combustible
materials other than wood flooring.
† Left side requires 3 in. if a single wall vent is used on 14-1/2
in. cabinets.
Figure 9.
Return Air
Return air must be brought in through the top of the furnace
installed in an downflow application.
Improper installation of the furnace can result in
personal 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 furnace
should be sealed airtight to the return air plenum. 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. Allow absolutely no sagging,
cracks, gaps, etc.
For no reason should return and supply air duct systems
ever be connected to or from other heating devices
such as a fireplace or stove, etc. Fire, explosion, carbon
monoxide poisoning, personal injury and/or property
damage could result.
WARNING
Installation on Non-Combustible Flooring
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.
