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COMBUSTION
AIR REQUIREMENTS
(Minimum Opening
Requirement)
91,000
19
100
23
46
140,000
28
140
35
70
175,000
35
175
44
88
210,000
42
210
53
106
245,000
49
245
61
122
280,000
56
280
61
140
A space w hose volume is not less than 50 cubic feet per 1000 BTU/Hour of all
appliances
installed in that space (cubic feet of space = height x width x length)
** A space w hose volume is less than 50 cubic feet per I000
BTU/Hour of all
appliances
installed in that space (cubic feet of space = height x w idth x length)
1. Ventilation
of boiler
room
must
be adequate
enough
to provide
sufficient
air to properly
support
combustion
and venting.
2. When the boiler is located in an unconfined
space
in a building
of conventional
construction
frame,
masonry
or metal, infiltration
normally
is adequate
to
provide air for combustion
and ventilation.
However,
in any building
which has been altered to conserve
energy
or to minimize
infiltration,
the boiler
area
should be considered
as a confined space. If there is
anydoubt,
install airsuppty
provisions
for combustion
and ventilation
in accordance
with section 5.3, Air for
Combustion
and Ventilation,
of the NFPA 54 1988
code, the recommendations
that follow, or applicable
provisions
of the local building
codes.
3. When
the boiler
is installed
in an unconfined
space,
in a building
of unusually
tight construction,
air
for combustion
and room ventilation
must be
obtained
from
outdoors
or from
spaces
freely
communicating
with
the
outdoors.
A permanent
opening
or openings
having a total free area of not
less than 1 square
inch per 5,000
BTU per hour of
total input rating of att appliances
shall be provided.
Ducts may be used to convey
make-up
air from the
outdoors
and shall have the same cross-sectional
area of the openings
to which they are connected.
4. When
air for
combustion
and
room
ventilation
is from
inside
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 1,000
BTU per hour of the total
input rating ofatl appliances
in the enclosed
space, but must not be less than 100 square
inches.
These
openings
must
freely
communicate
with the interior areas having
adequate
infiltration
from
the
outside.
(Figure
1)
J
_
i ¸
jl
f
C_O_NE'_
iL
TYr=_
VErsT
r_pE
VENf
_'i "' E
_J
I FIGURE 1 I
5. When
the boiler is installed
in a confined
space
and atl air is provided from the outdoors,
the confined
space shall be provided with two permanent openings,
one commencing
within 12 inches from the top and
one commencing
12 inches from 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.
One of the following
methods
must
be used
to
provide adequate
air for ventilation
and combustion.
A. When directly communicating
with the outdoors,
each 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.
(Figure
2)
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