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2
INSTALLATION
2.10 Combustion Air Requirements
Combustion air intake has a factory-preset air orifice.
If indoor combustion air is to be supplied for a tightly
closed room, one square inch of free air opening
should be provided for each 5000 BTUh of heater
input.
Noncontaminated air for combustion must be ducted
to the heater if chlorinated or fluorinated
contaminants are present in the area where the heater
is installed, or if the building has a negative pressure.
Typical sources of these contaminants are refrigerants,
solvents, adhesives, degreasers, paint removers, paints,
lubricants, pesticides, etc.
Outside combustion air may be provided by an
accessory 4 in./10.2cm air duct, and directly attached
over the air orifice (see Figure 2.10.1). A BR-VC wall
inlet vent cap must be used with horizontal outside
air intake ducts.
Do not install filters on combustion air.
The intake terminal must be installed to prevent
blockage by snow.
NOTE: Use insulated duct or PVC pipe to prevent
condensation on outer surface. Keep intake opening
at least 3 ft. from any exhaust vent openings. For
limitations of length and size, see Air Duct Chart.
When vertical roof venting the combustion air intake
and exhaust, the exhaust should terminate higher
than the intake.
Two 90 degree elbows are included in duct length.
The air intake terminal must be installed at least one
foot above grade.
AIR INTAKE DUCT CHART
MODEL
ALL
MODELS
Figure 2.10.1
20
AIR INTAKE
MAXIMUM
DUCT SIZE
INTAKE LENGTH
IN.
CM
FT.
4
10.2
35
5
12.7
50
M
10.67
15.24
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