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Determination of Appliance
Category for Venting Purposes and
Venting Arrangements
WARNING: Contact the manufacturer of the vent
material if there is any question about the appliance
categorization and suitability of a vent material for
application on a Category III or IV vent system.
Using improper venting materials can result in
personal injury, death or property damage.
Support of Vent Stack
The weight of the vent stack or chimney must not rest
on the boiler vent connection. Support must be provid-
ed in compliance with applicable codes. The vent
should also be supported to maintain proper clear-
ances from combustible materials.
Use insulated vent pipe spacers where the vent pass-
es 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. 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 termi-
nation to avoid possibility of property damage or
personal injury.
a) Gases may form a white vapor plume in winter.
The plume could obstruct a window view if the ter-
mination is installed in close proximity to windows.
b) Prevailing winds could cause freezing of conden-
sate and water/ice buildup on building, plants or
roof.
c) The bottom of the vent terminal and the air intake
shall be located at least 12 inches above grade,
including normal snow line.
d) Un-insulated single-wall metal vent pipe shall not
be used outdoors on cold climates for venting gas
utilization equipment.
e) Through-the-wall vents for Category II and IV
appliances and non-categorized condensing appli-
ances shall not terminate over public walkways or
over an area where condensate or vapor could
create a nuisance or hazard or could be detrimen-
tal to the operation of regulators, relief valves, or
other equipment. Where local experience indi-
cates that condensate is a problem with Category
I and III appliances, this provision shall also apply.
f)
Locate and guard vent termination to prevent acci-
dental contact by people and pets.
g) DO NOT terminate vent in window well, stairwell,
alcove, courtyard or other recessed area, unless
previously approved by local authority.
h) DO NOT terminate above any door, window, or
gravity air intake. Condensate can freeze causing
ice formations.
i)
Locate or guard vent to prevent condensate from
damaging exterior finishes. Use a 2' x 2' rust
resistant sheet metal backing plate against brick
or masonry surfaces.
j)
DO NOT extend exposed vent pipe outside of
building. Condensate could freeze and block vent
pipe.
k) Multiple direct vent caps, when installed in the
same horizontal plane, should have a three (3)
foot clearance from the side of one vent cap to the
side of the adjacent vent cap(s).
U.S. Installations
Refer to latest edition of the National Fuel Gas Code.
Vent termination requirements are as follows:
a) Vent must terminate at least four (4) feet below,
four (4) feet horizontally, or one (1) foot above any
door, window or gravity air inlet to the building.
b) The vent must not be less than seven (7) feet
above grade when located adjacent to public walk-
ways.
c) Terminate vent at least three (3) feet above any
forced air inlet located within ten (10) feet.
d) Vent must terminate at least four (4) feet horizon-
tally, and in no case above or below unless four (4)
feet horizontal distance is maintained, from elec-
tric meters, gas meters, regulators, and relief
equipment.
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