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Counterflow Installation Over a Noncombustible Floor
Before setting the furnace over the plenum opening, ensure
that the surface around the opening is smooth and level. A
tight seal should be made between the furnace base and
floor by using a silicone rubber caulking compound or
cement grout.
Counterflow Installation Over a Combustible Floor
If installation over a combustible floor becomes necessary,
use an accessory subbase (see Specification Sheet
applicable for your model for details). A special accessory
subbase must be used for upright counterflow unit
installations over any combustible material, including wood.
Refer to subbase instructions for installation details. Follow
the instructions with the subbase for proper installation.
NOTES:
Do not install the furnace directly on carpeting, tile or
other combustible material other than wood flooring.
The subbase will not be required if an air conditioning coil
is installed between the supply air opening on the furnace
and the floor.
Clearances and Accessibility
Unobstructed front clearance of 24" (61 cm) for servicing is
recommended.
Clearances to Combustibles—in. (cm)
Vent Pipe
B1-Vent
Single Wall
Connector Sides Front Back Top (Plenum)
1 (2.5)
6 (15.2)
1 (2.4)
NOTE: Top clearance for horizontal configuration is 1" (2.5 cm).
A
Clear Combust G 2009
A. Top clearance—1" (2.5 cm)
B. Vent pipe clearance—6" (15.2 cm)
for single wall connector, 1"
(2.5 cm) for B-1 vent
3 (7.6)
0
1 (2.5)
B
C
E
C. Back clearance—0"
D. Side clearance—1" (2.5 cm)
E. Front clearance—3" (7.6 cm)
Adequate combustion/ventilation air must be supplied to the
closet or enclosure.
Furnace must be completely sealed to the floor or base.
Combustion/ventilation air supply pipes must terminate 12"
(30.5 cm) from the top of the closet or enclosure and 12"
(30.5 cm) from the floor of the closet or enclosure.
NOTE: Do not remove the solid base plate for the side return.
Return air ducts must be completely sealed to the furnace
and terminate outside the enclosure surfaces.
Horizontal Installation—WGFM28 Models Only
Line contact to framing is permitted when installed in the
horizontal configuration. Line contact is defined as the portion of
the cabinet that is formed by the intersection of the top and side.
IMPORTANT: Accessibility clearance, where greater, should take
precedence over minimum fire protection clearance.
A gas-fired furnace for installation in a residential garage
must be installed so that the ignition source and burners are
located not less than 18" (45.7 cm) above the floor and are
protected or located to prevent physical damage by vehicles.
A gas furnace must not be installed directly on carpeting, tile,
or other combustible materials other than wood flooring.
If suspending the furnace from rafters or joists, use ³⁄₈" threaded
rod and 2" x 2" x ¹⁄₈" (5.1 cm x 5.1 cm x 3.2 mm) angle iron as
shown in "Suspended Furnace" illustration. The length of rod will
depend on the application and the clearances necessary.
NOTE: In a horizontal installation, the air conditioning coil must
be adequately supported by the proper brackets and supports.
Inadequate coil support can result in furnace cabinet distortion
and air leakage.
Suspended Furnace
H
G
D
A. ³⁄₈ " (1 cm) diameter threaded
rod (6)
B. 8" (20.3 cm) minimum clearance
between center rod and furnace
cabinet to allow for circulator
blower removal.
C. Level furnace end to end, slight
forward tilt with front 0" to ³⁄₄ "
(1.9 cm) below back.
Furnace Suspension
B
A
F
E
D. Tilt outward to allow for door
and circulator blower removal.
E. Position as close as possible to
blower deck to allow for
circulator blower removal.
F. 2" x 2" x ¹⁄₈ " (5.1 cm x 5.1 cm x
3.2 mm) angle iron (3)
G. Support nuts
H. Hold down nuts
C
D
7
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