Roberts Gorden NDUSTRIA NHE Series, Installation, Operation & Service Manual

Page: 55 / 78

SECTION 8: V
ENTING
51
8.16 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 termination while maintaining a
minimum distance of 3' (93 cm) for both vertical and
horizontal venting.
8.16.1 Length Requirements
Follow the constraints listed on Page 44, Section 8.8 .
8.16.2 Vertical Outside Air Supply for Single Heater Installation
Description Part Number
Vent Cap, Metalbestos - 4" (10 cm) 90502300