Installation guide

INSTALLATION INSTRUCTIONS Gas Furnace: (F/G)9MXT, (F/G)9MXE
440 01 4005 05 23
Specifications subject to change without notice.
Leveling Legs (If Desired)
In upflow position with side return inlet(s), leveling legs may be
used. (See Figure 22) Install field−supplied, 5/16 x 1−1/2−in. (8
x 38 mm) (max) corrosion−resistant machine bolts, washers
and nuts.
Figure 22 Leveling Legs
A89014
NOTE: Bottom closure must be used when leveling legs are
used. It may be necessary to remove and reinstall bottom
closure panel to install leveling legs. To remove bottom closure
panel, see Figure 21 and Figure 20.
To install leveling legs:
1. Position furnace on its back. Locate and drill a hole in
each bottom corner of furnace.
2. For each leg, install nut on bolt and then install bolt with
nut in hole. (Install flat washer if desired.)
3. Install another nut on other side of furnace base. (Install
flat washer if desired.)
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: The furnace must be pitched as shown in Figure 19 for
proper condensate drainage.
Supply Air Connections
NOTE: For downflow applications, this furnace is approved for
use on combustible flooring when any one of the following two
accessories are used (see specification sheets for list of
approved accessories):
 Special Base − NAHA01101SB
 Cased Coil Assembly − EAM4X, END4X, ENW4X,
EAD4X
1. Determine application being installed from Table 5.
2. Construct hole in floor per Table 5 and Figure 23.
3. Construct plenum to dimensions specified in Table 5
and Figure 23.
4. Install as shown in Figure 25. If Coil Assembly Part is
used, install as shown in Figure 26 .
Figure 23
Floor and Plenum Opening
Dimensions
A96283
NOTE: It is recommended that the perforated supply−air duct
flanges be completely 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 Figure 24)
CAUTION
!
CUT HAZARD
Failure to follow this caution may result in personal injury.
Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts, and servicing furnaces.
Connect supply−air duct to supply−air outlet on furnace. Bend
flange inward past 90_ with wide duct pliers (See Table 1
Figure 24) The supply−air duct must be connected to ONLY
the furnace supply outlet or air conditioning coil casing (when
used). When installed on combustible material, supply−air duct
must be connected to ONLY the factory−approved accessory
subbase, or a factory−approved air conditioning coil casing. DO
NOT cut main furnace casing to attach supply air duct,
humidifier, or other accessories. All supply−side accessories
MUST be connected to duct external to furnace casing.
Return Air Connections
WARNING
!
FIRE HAZARD
A failure to follow this warning could cause personal injury,
death and/or property damage.
Never connect return−air ducts to the back of the furnace.
Follow instructions below.
The return−air duct must be connected to return−air opening
(bottom inlet) as shown in Figure 29. DO NOT cut into casing
sides (left or right). Bypass humidifier connections should be
made at ductwork or coil casing sides exterior to furnace. (See
Figure 29)
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel installed
in bottom return−air opening. Remove and discard this panel