5
VENTILATION AND COMBUSTION AIR
Ventilation of boiler room must be adequate enough to
1.
provide sufficient air to properly support combustion,
venting and maintain safe ambient temperatures under
normal operating conditions.
When the 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. If there is any
doubt, install air supply provisions for combustion
and ventilation in accordance with Chapter 5, Air for
Combustion and Ventilation, of NFPA 31, Standard
for the Installation of Oil Burning Equipment. The
recommendations that follow, or applicable provisions
of the local building codes.
When the 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.
When air for combustion and room ventilation is from
4.
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 of all 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.
See Figure #3.
COMBUStION aIR REQUIREMENtS
(Minimum Opening Requirement)
BTU/Hr Input
Unconfined Area*
Confined Area**
Outside
Inside
Outside Combustion Air
Combustion Air 1 Sq.
In./5000 BTU/Hr
(Step 4)
Combustion Air 1 Sq.
In./1000 BTU/Hr
(Min. 100 Sq. In.) (Figure #1)
Vertical Ducts 1 Sq. In./4000 BTU/
Hr (Figures # 2 & #3)
Horizontal Ducts 1 Sq. In./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
* A space whose 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 whose volume is 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)
VENTS
CHIMNEY
OR
L TYPE VENT PIPE
VENT PIPE
BASEBOARD
12"
12"
!
WARNING
Air openings to combustion area must not be obstructed. By following the instructions below,
adequate combustion air can be maintained.
Figure #3
