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SECTION 8: VENTING
39 of 59
8.11 Outside Combustion Air Supply
IMPORTANT: If the building has a slight negative
pressure or corrosive contaminants, such as
halogenated hydrocarbons, are present in the air, an
outside combustion air supply to the heater is
required. Seal all combustion air pipe joints.
Use of optional outside combustion air is not
recommended with unvented heaters.
The air supply duct may have to be insulated to
prevent condensation on the outer surface. The
outside air terminal must not be more than 1' (31 cm)
above the vent terminal.
8.11.1 Length Requirements
Follow the constraints listed on Page 36, Section 8.6.
8.11.2 Vertical Outside Air Supply for Single Heater Installation
8.11.3 Horizontal Outside Air Supply for Single Heater Installation
Description Part Number
Vent Cap 4" (10 cm) 90502300
Band Clamp
(Recommended)
Flex Hose
(Recommended)
Vent Cap
Wall
4" (10 cm)
Single Wall Pipe
Burner
Description Part Number
Vent Cap 4" (10 cm) 90502300