7
VENTILATION & COMBUSTION AIR
buildings, the confined space shall be provided with
two permanent openings, one starting 12 inches from the
top and one 12 inches from the bottom of the enclosed
space. Each opening shall have a minimum free area
of 1 square inch per one thousand (1000) BTU per hour
of the total input rating of all appliances in the enclosed
space, but must not be less than one hundred (100)
square inches. These openings must freely communicate
directly with other spaces of sufficient volume so that the
combined volume of all spaces meets the criteria for an
unconfined space. See
Figure #1.
VENT PIPE
BASEBOARD
VENTS
BOILER
12"
12"
Figure #1
When the boiler is installed in a confined space and all air
5.
is provided from the outdoors the confined space shall be
provided with one or two permanent openings according
to methods A or B. When ducts are used, they shall be
of the same cross sectional area as the free area of the
area of the openings to which they connect. The mini
-
mum dimension of rectangular air ducts shall be not less
than 3 x 3 inches or 9 square inches.
When installing two openings, one must commence
A.
within 12 inches from the top and the other within 12
inches from the bottom of the enclosure. The open
-
ings shall communicate directly, or by ducts, with the
outdoors or spaces (crawl or attic) that freely commu
-
nicate with the outdoors. One of the following methods
must be used to provide adequate air for ventilation
and combustion.
When directly communicating with the outdoors, each
I.
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. See
Figure #2
.
OUTLET
AIR
VENTILATION LOUVERS
(EACH END OF ATTIC)
INLET
AIR
VENTILATION
LOUVRES FOR
UNHEATED
CRAWL SPACE
Figure #2
When communicating with the outdoors by means of
II.
vertical ducts, each opening shall have a minimum
free area 1 square inch per 4,000 BTU per hour of
total input rating of all appliances in the enclosed
space. See
figure #3
.
BOILER
OUTLET
AIR
VENTILATION LOUVERS
(EACH END OF ATTIC)
-- SLAB --
INLET AIR DUCT
12"
(DUCT ENDS 1 FT.
ABOVE THE FLOOR)
Figure #3