Downflow Installation; Bottom Return Air Inlet - Carrier N8MXL Installation Instructions Manual

80% single stage, ecm motor category i, gas furnace
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5/ 16
(8mm)
5/ 16
1
3
/
4
(44mm)
(8mm)
5
/
16
(44mm)
1
3/ 4
1
3/ 4
(44mm)
Fig. 10 − Leveling Legs
4. Adjust outside nut to provide desired height, and tighten
inside nut to secure arrangement.
5. Reinstall bottom closure panel if removed.

DOWNFLOW INSTALLATION

NOTE: For downflow applications, this furnace is approved for
use on combustible flooring when any one of the following 3
accessories are used:
S
Downflow combustible floor subbase
S
Cased Coil numbers END4X, ENW4X
S
Coil casing model number NAEA
1. Determine application being installed from Table 4.
2. Construct hole in floor per Table 4 and Fig. 11.
3. Construct plenum to dimensions specified in Table 4 and
Fig. 11.
4. If downflow subbase is used, install as shown in Fig. 12. If
Coil model number END4X, ENW4X or Coil Casing
model number NAEA is used, install as shown in Fig. 13.
NOTE: It is required that the perforated supply−air duct flanges
be completely folded over or removed from furnace when
installing the furnace on a factory−supplied cased coil or coil box.
To remove the supply−air duct flange, use wide duct pliers or
hand seamers to bend flange back and forth until it breaks off. Be
careful of sharp edges. (See Fig. 14.)

Bottom Return Air Inlet

These furnaces are shipped with bottom closure panel installed in
bottom return−air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:
1. Tilt or raise furnace and remove two screws holding bot-
tom filler panel. (See Fig. 9.)
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws
441 01 1422 00
(8mm)
1
3
/
4
(44mm)
(8mm)
5/ 16
A89014
Specifications are subject to change without notice.
A
PLENUM
OPENING
B
FLOOR
OPENING
C
Fig. 11 − Floor and Plenum Opening Dimensions
FURNACE
(OR COIL CASING
WHEN USED)
COMBUSTIBLE
FLOORING
DOWNFLOW
SUBBASE
SHEET METAL
PLENUM
FLOOR
OPENING
Fig. 12 − Furnace, Plenum, and Subbase Installed
on a Combustible Floor
D
A96283
A96285
11

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