Installation; Upflow Installation - International comfort products N8MXL Installation Instructions Manual

in 12" (300 mm) of the floor. The minimum dimension
of air openings shall be at least 3 in. (80 mm). (See
Figure 8)
c. Combining space on different floor levels. The
volumes of spaces on different floor levels shall be
considered as communicating spaces if connected by
one or more permanent openings in doors or floors
having free area of at least 2 in.
2
mm /kW) of total input rating of all gas appliances.
Figure 8 − Air for Combustion, Ventilation, and Dilution
from Indoors
CIRCULATING AIR
DUCTS
INTERIOR
HEATED
SPACE
CIRCULATING AIR DUCTS
2
*Minimum opening size is 100 in. with minimum dimensions of 3 in. (76 mm).
*Minimum of 3 in. (76 mm), when type −B1 vent is used.
2. An attic or crawlspace may be considered a space that
freely communicates with the outdoors provided there
are adequate permanent ventilation openings directly
to outdoors having free area of at least 1−in.
Btuh of total input rating for all gas appliances in the
space.
3. In spaces that use the Indoor Combustion Air Meth-
od, infiltration should be adequate to provide air for
combustion, permanent ventilation and dilution of flue
gases. However, in buildings with unusually tight con-
struction, additional air MUST be provided using the
methods described in the Outdoor Combustion Air
Method section.
Unusually tight construction is defined as construction with:
a. Walls and ceilings exposed to the outdoors have a
continuous, sealed vapor barrier. Openings are gas-
keted or sealed and
b. Doors and openable windows are weatherstripped
and
c. Other openings are caulked or sealed. These include
joints around window and door frames, between sole
plates and floors, between wall−ceiling joints, between
wall panels, at penetrations for plumbing, electrical
and gas lines, etc.
10
2
/1,000 Btuh (4,400
VENT THROUGH ROOF
12" MAX (305mm)
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
UNCONFINED
SPACE
6" MIN (152mm)
(FRONT)
Ü
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MA X (305mm)
A03175
2
/4,000
Specifications are subject to change without notice.
Combination of Indoor and Outdoor Air
1. Indoor openings shall comply with the Indoor Combus-
tion Air Method below and,
2. Outdoor openings shall be located as required in the
Outdoor Combustion Air Method mentioned previ-
ously and,
3. Outdoor openings shall be sized as follows:
a. Calculate the Ratio of all Indoor Space volume divided
by required volume for Indoor Combustion Air Meth-
od below.
Figure 9 − Removing Bottom Closure Panel
BOTTOM
CLOSURE
PANEL
BOTTOM
FILLER PANEL
b. Outdoor opening size reduction Factor is 1 minus the
Ratio in a. above.
c. Minimum size of Outdoor openings shall be the size
required in Outdoor Combustion Air Method above
multiplied by reduction Factor in b. above. The minim-
um dimension of air openings shall be not less than
3 in. (80 mm).

INSTALLATION

UPFLOW INSTALLATION

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
bottom filler panel. (See Figure 9)
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws.
Side Return Air Inlet
These furnaces are shipped with bottom closure panel
installed in bottom return−air opening. This panel MUST be in
place when only side return air is used.
NOTE: Side return−air openings can be used in UPFLOW
and most HORIZONTAL configurations. Do not use side
return−air openings in DOWNFLOW configuration.
Leveling Legs (If Desired)
In upflow position with side return inlet(s), leveling legs may
be used. (See Figure 10) Install field−supplied, 5/16 x 1−1/2
in. (8 x 38 mm) (max) corrosion−resistant machine bolts,
washers and nuts.
NOTE: Bottom closure must be used when leveling legs are
used. It may be necessary to remove and reinstall bottom
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