WARNING
Failure to provide an adequate supply of fresh air for combustion will result in hazardous
operating conditions.
Note
If you use a fireplace or a kitchen or bathroom exhaust fan, you should install an outside
air intake. These devices will rob the boiler and water heater of combustion air.
1. In unconfined spaces in buildings infiltration may be adequate to provide air for
combustion and ventilation. However, in buildings of unusually tight
construction, additional air must be provided as described in Item2. (b) below.
2. Boiler located in confined space:
[Note: Confined space may be defined as a space whose volume is less than 50
cubic feet per 1000 Btuh of total input of all appliances installed in that space.]
(a) All air from inside of building:
Providing infiltration in the rest of the building is adequate, the
confined space may be provided with two permanent openings
communicating directly with another room or rooms of sufficient
volume that the total volume of all spaces meets the criteria for
unconfined space. One opening must be within 12 inches of the
bottom of the enclosure. See Figure 7.
Figure 7.
Note: Each opening
shall have a free
area of not less than
one square inch per
1,000 Btu per hour of
the total input rating
of all equipment in
the enclosure, but
not less than 100
square inches.
Opening
Chimney
Opening
14 Installation, Operation, And Service Instructions