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FRESH
AIR FOR
COMBUSTION
WARNING
I
Be sure to provide
enough
fresh air for combustion.
Enough
air ensures
proper
combustion
and assures
that no hazard
will develop
due to the lack of oxygen.
I
NOTE
[
If you use a fireplace
or a kitchen
or a bathroom
exhaust
fan, you should
install
an
outside
air intake.
These
devices
will rob the boiler
and water
heater
of combustion
air.
You must provide
enough
flesh air to assure proper combustion.
The fire in the boiler uses oxygen.
It must have a
continuous
supply.
The air in the house contains only enough oxygen to supply the burner for a short time. Outside
air must enter the house to replace the air used by the burner.
Study the following
examples
1 and 2 to determine
your
fresh air requirements.
EXAMPLE
1: Boiler
Located
in Unconfined
Space
If your boiler is in an open area (unpartitioned
basement)
in a conventional
house, the air that leaks through the cracks
around the doors and windows
will usually be adequate to provide air for combustion.
The doors should not fit tightly.
Do not caulk the cracks around the windows.
An unconfined
space is defined as a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour of the
total input rating of all appliances
installed
in that space.
EXAMPLE
2: Boiler Located in Confined
Space
A. All Air from
Inside
the Building:
The confined
space shall be provided
with two permanent
openings
communicating
directly with an additional
room(s)
of sufficient
volume so that the combined
volume of all spaces
meets the criteria
for an unconfined
space.
The total input of all combustion
equipment
installed in the combined
space shall be considered
in making this determination.
Each opening
shall have a minimum
free area of one
square
inch per 1,000 Btu per hour of the 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 the top and one within 12 inches of the
bottom
of the enclosure.
Example:
Your boiler is rated at 100,000 Btu per hour.
The water heater is rated at 30,000 Btu per hour. The
total is I30,000
Btu per hour. You need two grilles, each with 130 square inches of FREE opening.
Metal grilles
have about 60% FREE opening.
To find the louvered
area needed, multiply
the free opening required by 1.7 (130
x 1.7 = 221.0 sq. in. louvered area).
In this example, two grilles each having
an 8" x 30" (24-0 sq. in.) louvered
area would he used.
AIR OPENINGS FOR BOILER LOCATED
IN CONFINED
SPACE (CLOSET OR UTILITY ROOM)
VENTILATING
I
GRILLE
1
I
I
I
I'
COMBUSTION
AIR
GRILLE
6
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