Lennox DAVE SIGNATURE SL280DFV Installation Instructions Manual page 9

Downflow Installation
Downflow unit installs in three ways: on non-combustible
flooring, on combustible flooring using a downflow com-
bustible flooring base, or on a reverse-flow cooling cabi-
net. Do not drag the unit across the floor.
Installation on Non-Combustible Flooring (FIGURE 6)
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 6
TABLE 1
NON-COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Front to Rear
Width
in
A (14.5") 19-3/4
B (17.5") 19-3/4
C (21") 19-3/4
NOTE - Door opening dimensions listed are 1/4 inch (6 mm) larger than the unit
opening. See unit dimensions on page 2 .
Installation on Combustible Flooring (FIGURE 7)
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.
SUPPLY AIR
PLENUM
Side to Side
mm in mm
502 13-1/4 337
502 16-1/4 413
502 19-3/4 502
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
COMBUSTIBLE FLOOR OPENING SIZE
Cabinet Front to Rear
Width
in
A (14.5") 2
B (17.5") 22
C (21") 22
NOTE - Floor opening dimensions listed are 1/4 inch (6 mm) larger than unit
opening. See unit dimensions on page 2.
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.
Installation on Cooling Cabinet (FIGURE 8)
1 - Refer to reverse-flow coil installation instructions for
correctly sized opening in floor and installation of
cabinet.
NOTE - Downflow combustible flooring kit is not used
2 - When cooling cabinet is in place, set and secure
the furnace according to the instructions that are
provided with the cooling coil. Secure the furnace
to the cabinet.
3 - Seal the cabinet and check for air leaks.
Page 9
CAUTION
SUPPLY AIR PLENUM
DOWNFLOW
COMBUSTIBLE
FLOORING BASE
FIGURE 7
TABLE 2
Side to Side
mm in
559 15-3/4
559 18-3/4
559 22-3/4
mm
400
476
578