Page 10
2 - After opening is cut, set the additive base into opening.
3 - Check fiberglass strips on additive base to make sure
they are properly glued and positioned.
4 - Lower supply air plenum into additive base until ple
num flanges seal against fiberglass strips.
5 - Set unit on additive base so unit flanges drop into ple
num. Refer to figure 8.
NOTE – Be careful not to damage fiberglass strips.
Check for tight seal.
C-Installation on Cooling Cabinet
1 - Refer to reverseflow coil installation instructions for
correctly sized opening in floor and installation of cabi
net.
2 - When cooling cabinet is in place, install furnace so
flanges drop inside cabinet opening.
3 - Seal cabinet and check for air leakage.
Horizontal Applications
The Lennox G24M furnace can be installed in horizontal
applications in either upflow or downflow configuration
(See figure 6). It is preferable to install the unit in the stan
dard upflow configuration, if possible, because the vent
pipe will not interfere with service access for blower. Install
two #10 screws in the cabinet bottom (upflow configura
tion) or cabinet top (downflow configuration) to provide a
better air seal.
The unit cannot be installed on its back.
Horizontal Application
Installation Clearances
Vent
Connector
Type
Type C
Type B1
TOP
0
0
*FRONT
2 in. (51 mm) 2 in. (51 mm)
BACK
0
0
SIDES
2 in. (51 mm) 2 in. (51 mm)
VENT
6 in. (152 mm) 1 in. (25 mm)
BOTTOM
TOP
RIGHT
SIDE
LEFT
SIDE
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 installations on a combustible floor, do not install
the furnace directly on carpeting, tile or other combus
tible materials other than wood flooring.
FIGURE 9
Allow for clearances to combustible materials as indicated
on the unit rating plate. Minimum clearances for closet or
alcove installations are shown in
figure 9.
Furnaces may be installed in either an attic or a crawlspace.
See figure 10 for furnace installations on a platform.
NOTE - When the furnace is installed on a platform in a
crawlspace, it must be elevated enough to avoid water
damage and to allow the air conditioning coil to drain.
Horizontal Application
Unit Installed on Platform
WORKING
PLATFORM
GAS
ENTRY
VENT
PIPE
NOTE - Line contact is permissible. See the unit rating plate for clearances.
FIGURE 10
Anyone of the following methods may be used to suspend the
furnace from roof rafters or floor joists:
1 - Using Lennox hanging bracket kit catalog num
ber 46J66 -
Install as indicated in the installation instructions
provided with the hanging bracket kit.
2 - Using angle iron with at least 1/4 in. diameter
rods -
Install as shown in figure 11.
Note - Rods must not interfere with plenum or ex
haust piping;
cooling coils and supply and return
air plenums must be supported separately.
Horizontal Application
Unit Suspended in Attic or Crawlspace
Using Angle Iron and Rods
1/4 in. ROD
ANGLE
IRON
SUPPORT TIES -
INSTALL TO PREVENT
SPREADING
Leave sufficient clearance between rod and unit to
remove access panels.
Level unit - side to side and end to end.
Secure the angle iron to the unit with sheetmetal screws:
maximum screw length - 3/4 in. and minimum screw size - # 10.
FIGURE 11
