INSTALLATION INSTRUCTIONS
Gas Furnace: (F/G)MAC
20
440 01 4201 01
Specifications subject to change without notice.
Table 5
Opening Dimensions
−
in. (mm)
FURNACE
CASING WIDTH
IN. (mm)
APPLICATION
PLENUM OPENING
FLOOR OPENING
A
B
C
D
17–1/2
(445)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
16
(406)
21
−
5/8
(549)
16
−
5/8
(422)
22
−
1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
15
−
7/8
(403)
19
(483)
16
−
1/2
(419)
19
−
5/8
(498)
Downflow applications on combustible flooring (subbase required)
15
−
1/8
(384)
19
(483)
16
−
3/4
(425)
20
−
5/8
(600)
Downflow Applications on Combustible Flooring with Coil Assembly or coil
box (subbase not required)
15
−
1/2
(394)
19
(483)
16
−
1/2
(419)
20
(508)
21
(533)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
19
−
1/2
(495)
21
−
5/8
(549)
20
−
1/8
(511)
22
−
1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
19
−
3/8
(492)
19
(483)
20
(508)
19
−
5/8
(498)
Downflow applications on combustible flooring
(subbase required)
18
−
5/8
(473)
19
(483)
20
−
1/4
(514)
20
−
5/8
(600)
Downflow Applications on Combustible Flooring with Coil Assembly or coil
box (subbase not required)
19
(483)
19
(483)
20
(508)
20
(508)
24
−
1/2
(622)
Upflow Applications on Combustible or Noncombustible Flooring
(subbase not required)
23
(584)
21
−
1/8
(537)
23
−
5/8
(600)
22
−
1/4
(565)
Downflow Applications on Noncombustible Flooring
(subbase not required)
22
−
7/8
(581)
19
(483)
23
−
1/2
(597)
19
−
5/8
(498)
Downflow applications on Combustible flooring
(subbase required)
22
−
1/8
(562)
19
(483)
23
−
3/4
(603)
20
−
5/8
(600)
Downflow Applications on Combustible Flooring with Coil Assembly or
coil box (subbase not required)
22
−
1/2
(572)
19
(483)
23
−
1/2
(597)
20
(508)
Figure 22
Furnace, Plenum, and Subbase
Installed on a Combustible Floor
A96285
HORIZONTAL INSTALLATION
NOTE
: The furnace must be pitched forward as shown in
Figure 17
for proper condensate drainage.
The furnace can be installed horizontally in an attic or
crawlspace on either the left
−
hand (LH) or right
−
hand (RH)
side. The furnace can be hung from floor joists, rafters or
trusses or installed on a non
−
combustible platform, blocks,
bricks or pad.
Figure 23
Furnace, Plenum, and Coil
Assembly on a Combustible Floor
A96284