18-CD30D1-12 9
Installer’s Guide
8
9
CONFINED
SPACE
7
Confined spaces are installations with less than 50 cu.
ft. of space per 1000 BTU/hr input from all equipment
installed. Air for combustion and ventilation requirements
can be supplied from inside the building as in Figure 8 or
from the outdoors, as in Figure 9.
1. All air from inside the building as in Figure 8: 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. Refer to
Table 3 for minimum open areas requirements.
2. All air from outdoors as in Figure 9: 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. Refer to Table 3, for minimum open
areas requirements.
TABLE 3
MINIMUM FREE AREA IN SQUARE INCHES
EACH OPENING (FURNACE ONLY)
Furnace
Maximum
BTUH/INPUT
Rating
Air
From
Inside
Air From Outside
Vertical
Duct
Horizontal
Duct
60,000
80,000
100,000
120,000
100
100
100
120
15
20
25
30
30
40
50
60
DUCT CONNECTIONS
Air duct systems should be installed in accordance with
standards for air conditioning systems, National Fire
Protection Association Pamphlet No. 90. They should be
sized in accordance with ACCA Manual D or whichever is
applicable.
Central furnaces, when used in connection with cooling
units, shall be installed in parallel or on the upstream
side of the cooling coil to avoid condensation in the heat
exchanger.
To Next Page
Loading...
Need help?
General