Outdoor Air Through Two Horizontal Ducts; Outdoor Air Through Two Vertical Ducts; Air From Other Indoor Spaces; Venting - A.O. Smith BL-80 Instruction Manual

OUTDOOR AIR THROUGH TWO HORIZONTAL DUCTS

FIGURE 10.
The confined space shall be provided with two permanent horizontal
ducts, one commencing within 12 inches (300 mm) of the top and
one commencing within 12 inches (300 mm) of the bottom of the
enclosure. The horizontal ducts shall communicate directly with the
outdoors. See Figure 10.
Each duct opening shall have a minimum free area of 1 square inch
per 2,000 Btu/hr (1100 mm2 per kW) of the aggregate input rating of
all appliances installed in the enclosure.
When ducts are used, they shall be of the same cross sectional area
as the free area of the openings to which they connect. The minimum
dimension of rectangular air ducts shall be not less than 3 inches.

OUTDOOR AIR THROUGH TWO VERTICAL DUCTS

The illustrations shown in this section of the manual are a
reference for the openings that provide fresh air into confined
spaces only.
DO NOT refer to these illustrations for the purpose of vent
installation. See Venting Installation on page 14 for complete
venting installation instructions.
FIGURE 11.
The confined space shall be provided with two permanent vertical
ducts, one commencing within 12 inches (300 mm) of the top and
one commencing within 12 inches (300 mm) of the bottom of the
enclosure. The vertical ducts shall communicate directly with the
outdoors. See Figure 11.
Each duct opening shall have a minimum free area of 1 square inch
per 4,000 Btu/hr (550 mm2 per kW) of the aggregate input rating of
all appliances installed in the enclosure.
When ducts are used, they shall be of the same cross sectional area
as the free area of the openings to which they connect. The minimum
dimension of rectangular air ducts shall be not less than 3 inches.

AIR FROM OTHER INDOOR SPACES

The confined space shall be provided with two permanent openings,
one commencing within 12 inches (300 mm) of the top and one
commencing within 12 inches (300 mm) of the bottom of the enclosure.
See Figure 12.
Each opening shall communicate directly with an additional room(s)
of sufficient volume so that the combined volume of all spaces meets
the criteria for an Unconfined Space.
Each opening shall have a minimum free area of 1 square inch per
1,000 Btu/hr (2200 mm2 per kW) of the aggregate input rating of all
appliances installed in the enclosure. Each opening shall not be less
than 100 square inches (645 cm2).

VENTING

14
FIGURE 12.