Operation and Installation Manual
6
1. 
Ventilation of boiler room must be adequate enough to 
provide sufcient air to properly support combustion.
2. 
When boiler is located in an unconned space in a 
building of conventional construction frame, masonry 
or metal, inltration normally is adequate to provide 
air for combustion and ventilation. However, in any 
building which has been altered to conserve energy 
or to minimize inltration, 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 NFPA 31: 
Standard for the Installation of Oil-Burning Equipment.
COMBUSTION AIR REQUIREMENTS
(MINIMUM OPENING IN SQUARE INCHES)
INPUT
(Mbh)
*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)
119 24 119 30 60
140 28 140 35 70
175 35 175 44 88
203 41 203 51 102
224 45 224 56 112
245 49 245 62 123
259 52 259 65 130
294 59 297 74 147
* Unconned 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).
** Conned 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).
3. 
When a boiler is installed in an unconned 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 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.
VENTILATION & COMBUSTION AIR
 WARNING
Asphyxiation, re hazard. Do not obstruct air 
openings to combustion area. Follow instructions 
below, to maintain adequate combustion air.
! 










