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9
IO-242C 05/05
Space, Unconfined.
For purposes of this Code, a space whose volume is not
less than 50 cubic feet per 1,000 BTU per hour of the
aggregate input rating of all appliances installed in that
space. Rooms communicating directly with the space in
which the appliances are installed through openings not
furnished with doors, are considered a part of the
unconfined space.
5.3.3 Equipment Located in Confined Spaces:
(a) All Air from Inside the Building: The confined space shall
be provided with two permanent openings communicating
directly with an additional room(s) of sufficient volume so
that the combined volume of all spaces meets the criteria
for an unconfined space. The total input of all gas utilization
equipment installed in the combined space shall be
considered in making this determination. Each opening
shall have a minimum free area of 1 square inch per 1,000
BTU per hour of the total input rating of all gas utilization
equipment in the confined space, but not less than 100
square inches. One opening shall be within 12 inches of
the top and one within 12 inches of the bottom of the
enclosure.
Furnace
Water
Heater
Opening
Chimney or Gas Vent
Opening
NOTE: Each opening must have
a free area of not less than one
square inch per 1000 BTU of
the total input rating of all equip-
ment in the enclosure, but not
less than 100 square inches.
Equipment Located in Confined Spaces;
All Air from Inside Building. See 5.3.3-a.
(b) All Air from Outdoors: The confined space shall be provided
with two permanent openings, one commencing within 12
inches of the top and one commencing within 12 inches of
the bottom of the enclosure. The openings shall
communicate directly, or by ducts, with the outdoors or
spaces (crawl or attic) that freely communicate with the
outdoors.
1. When directly communicating with the outdoors, each
opening shall have a minimum free area of 1 square
inch per 4,000 BTU per hour of total input rating of all
equipment in the enclosure.
Furnace
Water
Heater
Outlet Air
Chimney or Gas Vent
NOTE: The inlet and outlet air
openings must each have a free
area of not less than one square
inch per 4000 BTU of the
total input rating of all equipment
in the enclosure.
Inlet Air
Ventilation louvers for
unheated crawl space
A
lternate
air inlet
Ventilation louvers
(each end of attic)
Equipment Located in Confined Spaces; All Air from Outdoors—
Inlet Air from Ventilated Crawl Space and Outlet Air to Ventilated
Attic. See 5.3.3-b
2. When communicating with the outdoors through vertical
ducts, each opening shall have a minimum free area of
1 square inch per 4,000 BTU per hour of total input
rating of all equipment in the enclosure.
Furnace
Water
Heater
Outlet Air
Chimney or Gas Vent
NOTE: The inlet and outlet air
openings must each have a free
area of not less than one square
inch per 4000 BTU of the
total input rating of all equipment
in the enclosure.
Inlet air duct
[ends 1 ft (300 mm)
above floor]
Ventilation louvers
(each end of attic)
Equipment Located in Confined Spaces; All Air from Outdoors
Through Ventilated Attic. See 5.3.3-b.
3. When communicating with the outdoors through
horizontal ducts, each opening shall have a minimum
free area of 1 square inch per 2,000 BTU per hour of
total input rating of all equipment in the enclosure.
Furnace
Water
Heater
Chimney or Gas Vent
NOTE: The air duct openings
must have a free area of not
less than one square inch per
2000 BTU of the total input
rating of all equipment in the
enclosure*.
Outlet air duct
Inlet air duct
*If the appliance room is located against an outside wall and the
air openings communicate directly with the outdoors, each opening
shall have a free area of not less than one square inch per 4,000
BTU per hour of the total input rating of all appliances in the
enclosure.
Equipment Located in Confined Spaces;
All Air from Outdoors. See 5.3.3-b.