Lennox MERIT Series Installation Instructions Manual page 10

Installation on Non-Combustible Flooring Figure 14
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.
TABLE 1
NON-COMBUSTIBLE FLOOR OPENING SIZE
Front to Rear
Cabinet Width
in
B Cabinet 17 - 1/2" 19 - 3/4
C Cabinet 21" 19 - 3/4
NOTE - Floor opening dimensions listed are 1/4 inch (6 mm) larger than the
unitopening. See dimension drawing on page 2.
FURNACE
PROPERLY
SIZED FLOOR
OPENING
FIGURE 14
Installation on Combustible Flooring Figure 15
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
CAUTION
The furnace and combustible flooring base shall not be
installed directly on carpeting, tile, or other combustible
material other than wood flooring.
Side to Side
mm in mm
502 16 - 5/8 422
502 20 - 1/8 511
SUPPLY AIR
PLENUM
Page 10
TABLE 2
COMBUSTIBLE FLOORING BASE OPENING SIZE
Front to Rear
Cabinet Catalog
Width Number
in
B Cabinet
11M60 22
17 - 1/2"
C Cabinet
11M61 22
21"
FURNACE
PROPERLY
SIZED FLOOR
OPENING
FIGURE 15
2 - After opening is cut, set the combustible flooring
base into opening.
3 - Check fiberglass strips on the combustible flooring
base to make sure they are properly glued and
positioned.
4 - Lower supply air plenum into the combustible flooring
base until plenum flanges seal against fiberglass
strips.
NOTE - Be careful not to damage fiberglass 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 Coil Cabinet Figure 16
NOTE - Downflow combustible flooring kit is not used
1 - Refer to reverse-flow coil installation instructions for
correctly sized opening in floor and installation of
cabinet.
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.
Side to Side
mm in mm
559 18 - 3/4 476
559 22 - 3/4 578
SUPPLY AIR
PLENUM
COMBUSTIBLE
FLOORING BASE