J801X Installation Manual

6
Furnace
12" Max.
Water
Heater
Vent or
Chimney
NOTES:
Each opening must
be at least 100 sq. in.
or 1 sq. in. per 1,000
Btuh of total input rating,
whichever is greater.
Openings must start at
no more than 12 inches
from the top and bottom
of the enclosure.
12” Max.
See
Note
s
See Notes
TOTAL INPUT
RATING (BTUH)
MINIMUM FREE AREA
(EACH OPENING)
ROUND DUCT
DIAMETER
40,000 100 in
2
12 inches
60,000 100 in
2
12 inches
80,000 100 in
2
12 inches
100,000 100 in
2
12 inches
120,000 120 in
2
13 inches
140,000 140 in
2
14 inches
160,000 160 in
2
15 inches
current revision of the NFGC (ANSI Z223.1 / NFPA54).
Consult local codes for special requirements. These
requirements are for US installations as found in the
NFGC.
CAUTION:
Exhaust fans, clothes dryers, fireplaces and
other appliances that force air from the house
to the outdoors can create a negative pressure
inside the house, resulting in improper furnace
operation or unsafe conditions such as flame roll
out. It is imperative that sufficient air exchange
with the outdoors is provided to prevent
depressurization. Additional information about
how to test for negative pressure problems can
be found in the NFGC.
Air openings on top and front of the furnace and openings
in closet doors or walls must never be restricted. If the
furnace is operated without adequate air for combustion, it
may cause the flame rollout switch to activate and turn off
the gas supply to the burners.
IMPORTANT NOTE
This safety device is a manually reset switch. DO NOT
install jumper wires across these switches to defeat
their function or reset a switch without identifying
and correcting the fault condition. If a switch must be
replaced, use only the correct sized part specified in the
Replacement Parts List.
Installation In A Confined Space
A confined space is an area with volume less than 50
cubic feet per 1,000 Btuh of the combined input rates of all
appliances drawing combustion air from that space. Furnace
closets, small equipment rooms and garages are confined
spaces. Furnaces installed in a confined space which supply
heated air to areas outside the space must draw return air
from outside the space and must have the return air ducts
tightly sealed to the furnace.
The required sizing of these openings is determined by
whether inside or outside air is used to support combustion,
the method by which the air is brought to the space, and by
the total input rate of all appliances in the space. In all cases,
the minimum dimension of any combustion air opening is
3 inches.
Air From Inside
If combustion air is taken from the heated space, the two
openings must each have a free area of at least 1 in
2
per
1,000 Btuh of total input of all appliances in the confined
space, but not less than 100 in
2
of free area. See Figure
2 and the Example below.
EXAMPLE
If the combined input rate of all appliances is less than or
equal to 100,000 Btuh, each opening must have a free
area of at least 100 in
2
. If the combined input rate of all
appliances is 120,000 Btuh, each opening must have a
free area of at least 120 in
2
.
Outdoor Air from a Crawl Space or Vented Attic
When the openings can freely exchange air with the outdoors,
each opening shall have a minimum free area of 1 in
2
per 4,000
Btuh of total appliance input. The openings shall exchange
directly, or by ducts, with the outdoor spaces (crawl or attic)
that freely exchange with the outdoors. See Figure 3.
Outdoor Air Using Vertical Ducts
If combustion air is taken from outdoors through vertical
ducts, the openings and ducts must have a minimum free
area of 1in
2
per 4,000 Btuh of total appliance input. In
installations drawing combustion air from a ventilated attic,
both air ducts must extend above the attic insulation. See
Figure 4, (page 7).
Outdoor Air Using Horizontal Ducts
If combustion air is taken from outdoors through horizontal
ducts, the openings and ducts must have a minimum free
area of 1in
2
per 2,000 Btuh of total appliance input. See
Figure 5, (page 7).
Figure 2. Combustion Air Drawn from Inside
Figure 3. Combustion Air Drawn from a Crawl
Space or Vented Attic
Attic
Insulation
Crawl Space
Ventilated Louvers for
unheated crawl space
Inlet air duct must be at
least 1 sq. in. per 4,000
Btuh of total input rating.
Outlet air duct must be
at least 1 sq. in. per
4,000 Btuh of total
input rating. Must
extend above attic
insulation
Water
Heater
Furnace
Vent or
Chimney
Ventilation louvers
at each end of attic