Installation Manual
14
√ Verify the air delivery of the furnace is adequate to
handle the static pressure drop of the coil, filter, and
duct work.
Locating the Unit
• The dimensions of the room or alcove must be able to
accommodate the overall size of the unit and required
clearances to combustible materials listed in Table 1
(page 5). Access for positioning and servicing must also
be considered when locating the unit. To determine
the required clearances needed for installation and
combustible materials, refer to Figure 24 (page 29),
Figure 25 (page 30), Figure 26 (page 31) and Figure
27 (page 32) for overall dimensions.
• The furnace must be installed on a solid surface and must
be level front-to-back and side-to-side at installation. The
surface that the furnace is mounted on must provide
sound physical support of the unit.
• The furnace should be installed as close to the center of
the air distribution system as possible and attached to
a properly installed duct system. Do not use the back
of the furnace for return air. See pages 10 - 11
for circulating requirements.
• The furnace must be installed so that all electrical
components are protected from water.
• The plenum attached to the A/C coil box and ductwork
within 3 ft. of the furnace must be installed so that
surfaces are at least 1/4” from combustible construction.
• When installed in a residential garage, the furnace must
be positioned so the burners and the source of the
ignition are located no less than 18 inches above the
floor and protected from physical damage by vehicles.
• This furnace is certified for use on wood flooring or
supports, but must not be installed directly on carpeting,
tile, or any combustible material other than wood flooring.
NOTE: The furnace may be installed on combustible
flooring when installed on a duct connector (Figure 8).
This factory supplied accessory must be installed in the
floor cavity and attached to the supply air duct before
the downflow furnace is installed.
• The furnace must be installed upstream from a
refrigeration system.
Locating & Cutting Floor Openings
IMPORTANT NOTE:
Cut-outs in the floor, must be carefully located to
avoid misalignment of the furnace.
To locate standard ducts, see Figure 9. For round ducts,
see Figure 10 (page 15).
1. Measure from the rear wall or alcove and mark the
centerline of the cut-out on the floor. Using the centerline
as a starting point, draw the rest of the duct cut-out to
the dimensions shown in Figure 9.
2. Cut out the floor opening to within 1” of the actual cutout
drawn.
3. Measure from the top of the floor down to the top of the
supply air duct to obtain the depth of the floor cavity.
NOTE: The depth of the floor cavity shown as “X” in
Table 4 will determine the correct duct connector.
NOTES:
With reducer installed: Opening to duct is 10-1/4” x 13-1/4”.
With reducer removed: Opening to duct is 13-1/4” x 13-1/4”.
REDUCER
(See Notes)
FELT-SEAL
SPACER
S
DUCT CONNECTOR TABS
FIBERGLASS
INSULATION
Figure 8. Duct Connector
14 1/2”
14 1/2”
Floor Cut-Out for
Duct Connector
FURNACE CABINET OUTLINE
Optional floor cutouts for gas,
condensate, or AC linesets
(3 1/2 x 1 1/2 - 2 places)
21 5/8
TYP.
1/2 TYP.
REAR WALL OF CLOSET OR ALCOVE
2 1/4
16 3/4
Furnace Door
1 1/2 TYP.
C
L
20"
2 3/4
Figure 9. Floor Cutout Dimensions
“X”
FLOOR OPENING
FLOOR
CAVITY
SUPPLY AIR DUCT
IF FLOOR CAVITY
(“X”) IS:
DUCT CONNECTOR
TYPE & PART NUMBER
FINGER TAB SCREW DOWN
7/8” (22) 901987A 904008
2” (51) 901988A N/A
4-1/4” (108) 901989A 904010
6-1/4” (159) 901990A 904011
8-1/4” (210) 901991A 904012
10-1/4” (260) 901992A 904013
12-1/4” (311) 901993A 904014
NOTE: Dimensions shown as Inches (Millimeter)
Table 4. Duct Connector Sizes