OWNER’S MANUAL MODEL: 8745 TUCSON Vent-Free HEATER
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MEETING FRESH AIR REQUIREMENTS
1.
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/hr (22 cm² / kW) of the total input rating of all
gas utilization equipment in the confined space, but
not less than 100 square inches (645 cm²). One
opening shall commence within 12 inches (30 cm) of
the top, and one opening shall commence within 12
inches (30 cm) of the bottom, of the enclosure. The
minimum dimension of air openings shall not be less
than 9 square inches (8 cm) (see Figure 3).
2.
All air from outdoors.
The confined space needs
to have two permanent openings, one commencing
within 12 inches (30 cm) of the top, and one
commencing within 12 inches (30 cm) of the bottom,
of the enclosure. The openings shall communicate
freely with the outdoors, either directly, by ducts, or
by spaces (crawl or attic). The minimum dimension
of air openings shall be not less than 9 square inches
(8 cm). See Figure 3.
A. Where directly communicating with the outdoors,
each opening shall have a minimum free area of 1
square inch per 4,000 BTU/hr (5.5 cm² / kW) of total
input rating of all equipment in the enclosure. See
Figure 3.
B. Where communicating with the outdoors through
vertical ducts, each opening shall have a minimum
free area of 1 square inch per 4,000 BTU/hr (5.5 cm² /
kW) of total input rating of all equipment in the
enclosure (See Figure 3).
C. Where communicating with the outdoors through
horizontal ducts, each opening shall have a minimum
free area of 1 square inch per 2,000 BTU/hr (11 cm² /
kW) of total input rating of all equipment in the
enclosure (See Figure 3).
D. Where ducts are used, they shall be of the same
cross-sectional area as the free area of the openings to
which they connect.
Figure 3
