6
Ventilation of boiler room must be adequate enough to
1.
provide sufficient air to properly support combustion.
When boiler is located in an unconfined space in a
2.
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. Provide combustion
air and ventilation air in accordance with the section
“Air for Combustion and Ventilation,” of the National
Fuel Gas Code, ANSI Z223.1 / NFPA 54, or applicable
provisions of local building codes.
When a boiler is installed in an unconfined space,
3.
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 all
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.
CombUStIoN aIR ReQUIRemeNtS
(mINImUm oPeNING IN SQUaRe INCHeS)
btU/HR
INPUt
*UNCoNfINeD aRea
**CoNfINeD aRea
oUtSIDe
CombUStIoN aIR
INSIDe
CombUStIoN aIR
oUtSIDe
CombUStIoN aIR
1 IN
2
/5000BTU/HR
(PARAGRAPH 4)
1 IN
2
/1000 BTU/HR
(MIN 100IN
2
)
(Figure 1)
1 IN
2
/4000 BTU/
HR
(Figures 2&3)
1 IN
2
/2000 BTU/
HR
(Figure 4)
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
* Unconfined area: A space whose volume is not less than 50 cubic feet per 1000 BTU per hour of all
appliances installed in that space (cubic feet of space = height x width x length).
** Confined area: A space whose volume is less than 50 cubic feet per 1000 BTU per hour of all appliances
installed in that space (cubic feet of space = height x width x length).
When air for combustion and room ventilation is from
4.
inside buildings, 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 (1,000)
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 with the interior areas having
adequate infiltration from the outside. See
figure #1.
When the boiler is installed in a confined space and
5.
all 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.
!
WARNING
Air openings to combustion area must not be obstructed. Follow chart below to obtain and maintain
adequate combustion air.
VENTILATION & COMBUSTION AIR
