Lennox G24M3/4-100 User Manual

Page 9
Downflow Applications
The Lennox G24M furnace is shipped in the upflow config
uration and must be converted for downflow installation.
Refer to figure 6 and the following steps to convert the unit
for downflow installation:
1 - Place unit on its back and remove access panel.
2 - Disconnect wire harness jackplugs from control
board.
3 - Disconnect sensor lead from control board.
4 - Remove four screws securing cabinet top cap to cabi
net.
5 - Remove four screws holding heat exchanger assem
bly in place. Slide heat exchanger out through top of
cabinet.
6 - Rotate heat exchanger 180
o
and slide back into cabi
net through top. Resecure using four screws.
7 - Remove four screws securing cabinet bottom piece
to cabinet. Replace with cabinet top cap.
8 - Use four screws to install cabinet bottom piece where
cabinet top was.
9 - Reconnect sensor lead to control board.
10- Reconnect wire harness jackplugs to control board.
11- Replace unit access panel.
12- Use cord clip located on right side of furnace to
hold wiring away from hot surfaces in heating
compartment. Install two #10 sheet metal screws in
cabinet top to provide a better air seal.
In downflow applications, the unit can be installed in three dif
ferent ways: on noncombustible flooring, on combustible
floor using an additive base, or on a reverseflow cooling cab
inet. Do not drag unit across floor.
Allow clearances to combustible materials as indicated on
unit rating plate. Minimum clearances for closet or alcove
installations are shown in figure 7.
DOWNFLOW INSTALLATION CLEARANCES
VENT
CONNECTOR
TYPE C TYPE B1
TOP 1" (25mm) 1" (25mm)
*FRONT 2" (51mm) 2" (51mm)
BACK 00
SIDES 00
VENT 6" (152mm) 1" (25mm)
TOP
BOTTOM
RIGHT
SIDE
LEFT
SIDE
NC - Non-combustible floor
*Front clearance in alcove installation must be a min. of 24" (610mm)
for front service access.
**With additive base on combustible floor.
FLOOR NC** NC**
(60 Hz. only)
FIGURE 7
A separate downflow filter kit is available for use in down
flow applications.
A-Installation on Non-Combustible Flooring
1 - Cut floor opening keeping in mind the clearances
listed on the unit rating plate. Also, keep in mind gas
supply and electrical supply, vent connections and
sufficient installation and service clearances. See
table 1 for correct floor opening size.
TABLE 1
NONCOMBUSTIBLE FLOOR OPENING
UNIT
Front to Rear Side to Side
UNIT
in mm in mm
G24M-45/60/75 19-3/4 502 15-1/4 388
G24M-100/120 19-3/4 502 18-3/4 477
G24M-140 19-3/4 502 21-1/2 546
NOTE - Floor opening dimensions listed are 1/4" (6mm) larger than unit
openings.
2 - Flange warm air plenum and lower into opening.
3 - Set unit over plenum.
4 - Check to see that an adequate seal is made.
B-Installation on Combustible Flooring
1 - When unit is installed on a combustible floor, an addi
tive base (ordered separately) must be installed be
tween the furnace and the floor. See table 2 for open
ing size to cut in the floor.
TABLE 2
ADDITIVE BASE FLOOR OPENING
UNIT
Front to Rear Side to Side
UNIT
in mm in mm
G24M-45/60/75 21-7/8 556 17-5/16 440
G24M-100/120 21-7/8 556 20-3/4 528
G24M-140 21-7/8 556 23-1/2 597
NOTE - Floor opening dimensions listed are 1/4" (6mm) larger than addi
tive base openings.
G24M UNIT
SUPPLY AIR
PLENUM
ADDITIVE
BASE
PROPERLY
SIZED FLOOR
OPENING
1. Cut correct size floor opening
2. Set additive base into opening.
3. Set supply air plenum into additive base.
4. Set unit.
COMBUSTIBLE FLOORING INSTALLATION
FIGURE 8

Lennox G24M3/4-100 Specifications

General

Brand	Lennox
Model	G24M3/4-100
Category	Furnace
Language	English