Ductwork And Filter (Downflow) - International comfort products N8MPN Installation Instructions Manual

11. Ductwork and Filter (Downflow)

WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in
personal injury or death.
Do NOT draw return air from inside a closet or
utility room where furnace is located. Return air
duct MUST be sealed to furnace casing.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in bodily
injury, death, and/or property damage.
Side return air duct(s) may cause excessive furnace
and/or air temperatures, which could result in death,
bodily injury, and/or property damage.
Return air duct is to be connected to only the top of
downflow furnace.
WARNING
!
BURN HAZARD
Failure to follow this warning could result in bodily
injury, death, and/or property damage.
The vent may be hot. Failure to install vent shield
properly could result in personal injury.
Install VENT PIPE SHIELD NAHA002VC as
described below.
Vent Shield
Vent shield is required for all downflow installations. The vent Must
exit out the side of the furnace for all downflow installations. This
places the hot vent pipe (over 300° F/149° C) within reach of
children. Vent shield attaches to side of furnace to cover vent pipe.
See Figure 5 in "Installation" section.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Place furnace on noncombustible subbase on
downflow applications, unless installing on
non!combustible flooring.
Outlet Duct Flange
Downflow installations with cased coils require the furnace outlet
duct flange to be bent outward and flat to mate the outlet of the
furnace to the cased coil.
Sub-Bases for Combustible Floors - Furnace Only
Note: When using the subbase for combustible floors, the
discharge air duct flanges on the furnace MUST be broken down to
provide proper fit up to the subbase. Use duct pliers to bend the
duct flanges flat onto the furnace casing. DO NOT bend the duct
flanges inward (toward the heat exchangers) as air flow
restrictions may occur.
441 01 2613 05
The Subbase for Combustible Floors MUST be used when a
downflow furnace is set on a combustible floor, even when the
furnace is installed on a coil box.
1. Cut the opening in the floor according to the dimensions in
Table 5 because the base is equipped with locating tabs that
center the base over the opening.
The opening in the base is 1
(28.6mm) narrower than the minimum required size of the
opening in the floor. This is done to maintain a 1" (25.4mm)
clearance between the floor and the plenum.
2. Fabricate the plenum to the dimensions given in Table 5.
Note that the dimensions given are outside dimensions.
3. Set the base over the opening in the floor, centering the
opening in the base over the opening in the floor. Fasten the
base to the floor with screws or nails. See Figure 27.
4. Drop the plenum through the opening in the base. The flange
of the plenum should rest on top of the combustible floor base.
Figure 27
2" (50.8mm)
Figure 28
Wood Screw
Specifications are subject to change without notice
Subject to change without notice.
National Excelsior Company
www.excelsiorhvac.com
1
/ " (31.8mm) shorter and 1
4
Exploded View of Sub!Base for
Furnace ONLY
S
T A = 4 1/4" (108mm) Minimum
clearance from back of hole
to wall or other obstruction.
Plenum
H
J
K
R
P
L
M
N
Hole in
Floor
A
Setting the Base
Furnace/Coil Box
Subbase
Insulation
1
/ "
8
2" (50.8mm)
1" (25.4mm)
25-20-46
Wood Floor
Plenum
25-20-46A
25