Fresh Air Openings For Confined Spaces - State Water Heaters SUF 60120 THRU Instruction Manual

FRESH AIR OPENINGS FOR CONFINED SPACES

The following instructions shall be used to calculate the size,
number and placement of openings providing fresh air for
combustion, ventilation and dilution in confined spaces. 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
venting installation instructions.
OUTDOOR AIR THROUGH TWO OPENINGS
Figure 9. Outdoor Air Through Two Openings
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. The openings shall communicate directly with
the outdoors. See .
Figure 9
Each opening shall have a minimum free area of 1 square inch
per 4,000 Btu/hr (550 mm
2
of all appliances installed in the enclosure. Each opening shall
not be less than 100 square inches (645 cm
OUTDOOR AIR THROUGH ONE OPENING
Figure 10. Outdoor Air Through One Opening
(page 21) for complete
per kW) of the aggregate input rating
2 ).
Alternatively a single permanent opening, commencing within 12
inches (300 mm) of the top of the enclosure, shall be provided.
See . The water heater shall have clearances of at least
Figure 10
1 inch (25 mm) from the sides and back and 6 inches (150 mm)
from the front of the water heater. The opening shall directly
communicate with the outdoors or shall communicate through a
vertical or horizontal duct to the outdoors or spaces that freely
communicate with the outdoors and shall have a minimum free
area of the following:
1. One square inch per 3000 Btu/hr (733 mm
input rating of all appliances located in the enclosure
2. Not less than the sum of the areas of all vent connectors in
the space
OUTDOOR AIR THROUGH TWO HORIZONTAL DUCTS
Figure 11. Two Horizontal Ducts
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
Each duct opening shall have a minimum free area of 1 square
inch per 2,000 Btu/hr (1100 mm
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.
18
2 per kW) of the total
.
Figure 11
per kW) of the aggregate input
2