Bradford White PDX1-40S6FBN Installation And Operating Instruction Manual page 10

Venting continued-
In locations where sustained outside air temperatures are below freezing, it is
possible for the vent terminations to accumulate ice build-up due to adverse local
climate conditions (prevailing wind direction, wind speed, termination orientation,
etc.). The optional concentric vent terminal is more resistant to this ice build-up.
In more severe temperature conditions, an optional manufacturer approved air
intake relief device is available and may be installed, per the instructions, to
prevent nuisance shut down of the water heater. The air intake relief device may
be installed with the concentric vent termination or the standard separate vent
terminations. Consult the concentric vent and/or the air intake relief device
instructions for installation requirements.
Vent pipes serving power vented appliances are classified by building codes as
"vent connectors". Required clearances from combustible materials must be
provided in accordance with information in this manual under LOCATION OF
WATER HEATER and CLEARANCES, and with National Fuel Gas Code and
local codes.
All vent pipes and terminals are to have a 1" minimum clearance to
combustibles. DO NOT use the placement of insulation or other materials in the
required clearance spaces surrounding the venting to combustible material
unless otherwise specified.
Risk of carbon monoxide poisoning or fire due to joint separation
or pipe breakage.
This water heater must be properly vented and connected to an
approved vent system in good condition. DO NOT operate water heater
with the absence of an approved vent system. A clean and
unobstructed vent system is necessary to allow noxious fumes that
could cause injury or loss of life to vent safely and will contribute toward
maintaining the water heater's efficiency. The acceptance of the
venting system is dependent upon full compliance with these installation
instructions.
Venting system must not pass through rated fire separations.
The venting system must be free to expand and contract. This venting
system must be supported in accordance with these instructions.
NOTICE
WARNING
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