G6RA, G6RK Service Manual 11
Figure 5. Equipment in a Confined Space with all
Combustion Air Drawn from the Outside
through Exterior Wall
Figure 6. Equipment in a Confined Space with All
Combustion Air Drawn from a
Crawl Space and Ventilated Attic
Figure 7. Equipment in a Confined Space with all
Combustion Air Drawn from the Outside through
Horizontal Ducts
If the unit is installed in an area with an exhaust fan, provide
sufficient ventilation to prevent negative pressures from
occurring in the room.
The combustion air openings must not be restricted in any
manner.
Air Directly Through An Exterior Wall
(See Figure 5)
If combustion air is provided directly through an exterior wall,
the two openings must each have free area of at least one
square inch per 4000 Btuh of total appliance input.
Outdoor Air Using a Crawl Space and Ventilated
Attic (See Figure 6)
When directly communicating with the outdoors, each opening
shall have a minimum free area of 1 square inch per 4,000
Btuh of total appliance input. The openings shall communicate
directly, or by ducts, with the outdoor spaces (crawl or attic)
that freely communicate with the outdoors.
Outdoor Air Using Horizontal Ducts (See Figure 7)
If combustion air is taken from outdoors through horizontal
ducts, the openings and ducts must have a minimum free
area of one square inch per 2,000 Btuh of total appliance
input.
If the unit is installed in an area with an exhaust fan, provide
sufficient ventilation to prevent negative pressures from
occurring in the room.
The combustion air openings must not be restricted in any
manner.
Outlet Air Duct
must be at least
1 sq. in. per 4000
Btuh of total input
rating. Must extend
above attic insulation.
Ventilation Louvers at
each end of attic
Attic Insulation
Ventilation Louvers for
unheated crawl space
Crawl Space
Inlet Air Duct must
be at least 1 sq. in.
per 4,000 Btuh of
total input rating.
Furnace
Water Heater
Vent or
Chimney
Each opening
to outside
must be at least
1 sq. in. per 2000
Btuh of total input
rating.
12" Max
12" Max
Total Input
Rating (Btu/hr)
40,000
60,000
80,000
100,000
120,000
140,000
160,000
Minimum
Free Area
(Each Opening)
20 sq. in.
30 sq. in.
40 sq. in.
50 sq. in.
60 sq. in.
70 sq. in.
80 sq. in.
Round Duct
Diameter
5"
6"
7"
8"
9"
10"
10"
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Furnace
Air Duct
Air Duct
Water Heater
Vent or
Chimney
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Do not supply combustion air from an attic
space that is equipped with power ventilation
or any other device that may produce a
negative pressure.
CAUTION:
!
Each opening
to outside
must be at least
1 sq. in. per 4000
Btuh of total input
rating.
12" Max
12" Max
Total Input
Rating (Btuh)
40,000
60,000
80,000
100,000
120,000
140,000
160,000
Minimum
Free Area
(Each Opening)
10 sq. in.
15 sq. in.
20 sq. in.
25 sq. in.
30 sq. in.
35 sq. in.
40 sq. in.
Round Duct
Diameter
4"
5"
5"
6"
6"
7"
8"
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Furnace
Water Heater
Vent or
Chimney
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