12
Support of Vent Stack
The weight of the vent stack or chimney must not rest on
the heater vent connection. Support must be provided
in compliance with applicable codes. The vent should
also be installed to maintain proper clearances from
where the vent passes through combustible roofs and
walls.
Vent Terminal Location
NOTE: During winter months check the vent cap and
make sure no blockage occurs from build-up of snow
or ice.
Condensate can freeze on the vent cap. Frozen
condensate on the vent cap can result in a blocked
flue condition.
Give special attention to the location of the vent
termination to avoid possibility of property damage
or personal injury.
Gases may form a white vapor plume in winter. The
plume could obstruct a window view if the termination
is installed near windows.
temperatures, can cause freezing of condensate and
The bottom of the vent terminal and the air intake
grade, including normal snow line.
equipment.
appliances shall not terminate over public walkways
or over an area where condensate or vapor could
create a nuisance or hazard or could be detrimental
to the operation of regulators, relief valves, or other
condensate is a problem with Category I and III
Combustion Air Supply
Exhaust
Heater Venting
Category
(Must be UL 1738 or ULC S636)
Combustion Air
Inlet Materials
From Inside Building
Vertical Venting IV
Metallic Vent
Horizontal
Venting
IV
From Outside Building
(Direct Vent or
Ducted Combustion Air)
Vertical Venting with
Ducted Combustion
Air
IV
Galvanized Steel
PVC
ABS
CPVC
Vertical Direct Vent IV
Horizontal Direct Vent IV
Table H. Venting Category Requirements
appliances, this provision shall also apply.
8. Locate and guard vent termination to prevent
accidental contact by people or pets.
DO NOT terminate vent in window well, stairwell,
alcove, courtyard or other recessed area.
window, or gravity air intake. Condensate can freeze,
causing ice formations.
Locate or guard vent to prevent condensate from
sheet metal backing plate against brick or masonry
surfaces.
DO NOT extend exposed vent pipe outside of
building beyond the minimum distance required for
the vent termination. Condensate could freeze and
block the vent pipe.
U.S. Installations
Refer to the latest edition of the National Fuel Gas Code.
door, window or gravity air inlet to the building.
grade when located adjacent to public walkways.
horizontal distance is maintained, from electric
meters, gas meters, regulators, and relief equipment.
adjacent walls.
roof overhang.
terminal clearance from the wall.
APPROVED
UNCONTROLLED DOCUMENT IF PRINTED
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