7
Provide adequate supply of combustion air in accordance
with requirements of authority having jurisdiction. In ab-
sence of such requirements
• United States. NFPA 31: Installation of Oil Burning
Equipment
• Canada. CSA B139: Installation of Oil Burning
Equipment
EXAMPLE 1: Boiler Located in Unconfined Space
If your boiler is in an open area (un-partitioned basement)
in conventional house, air that leaks through cracks around
doors and windows will usually be adequate to provide air
for combustion. Doors should not fit tightly. Do not caulk
cracks around windows.
An unconfined space is defined as space whose volume is
not less than 50 cubic feet per 1,000 Btu per hour of total
input rating of all appliances installed in that space.
EXAMPLE 2: Boiler Located in Confined Space
A.
All Air from Inside the Building:
Confined space
shall be provided with two permanent openings communi-
cating directly with additional room(s) of sufficient volume
so the combined volume of all spaces meets the criteria for
unconfined space. Total input of all combustion equipment
installed in combined space shall be considered in mak-
ing this determination. Each opening shall have minimum
free area of one square inch per 1,000 Btu per hour of total
input rating of all combustion equipment in the confined
space, but not less than 100 square inches. One opening
shall be within 12 inches of top and one within 12 inches of
bottom of the enclosure.
Example: Your boiler is rated at 100,000 Btu per hour. Wa
-
ter heater is rated at 30,000 Btu per hour. Total is 130,000
Btu per hour. You need two grilles, each with 130 square
inches of FREE opening. Metal grilles have about 60% FREE
opening. To find louvered area needed, multiply free open
-
ing required by 1.7 (130 x 1.7 = 221.0 sq. in. louvered
area). In this example, two grilles each having 8” x 30”
(240 sq. in.) louvered area would be used.
FRESH AIR FOR COMBUSTION
WARNING
Asphyxiation, fire hazard. Do not obstruct air
openings to combustion area. Follow instructions
below, to maintain adequate combustion air.
!
NOTICE
Install outside air intake if you use fireplace or
kitchen or bathroom exhaust fan. These devices rob
boiler and water heater of combustion air.
Figure 4 - Air Openings For Boiler Located In
Confined Space (Utility Room
)