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SECTION C: Installation
22
Vent Terminal Location
NOTICE: During winter months check the vent cap
and make sure no blockage occurs from build-up of
snow or ice.
1. Condensate can freeze on the vent cap. Frozen
condensate on the vent cap can result in a blocked
flue condition.
2. Give special attention to the location of the vent
termination to avoid possibility of property dam-
age or personal injury.
3. Gases may form a white vapor plume in winter.
The plume could obstruct a window view if the
termination is installed near windows.
4. Prevailing winds, in combination with below-
freezing temperatures, can cause freezing of con-
densate and water/ice build-up on buildings, plants
or roofs.
5. The bottom of the vent terminal and the air intake
shall be located at least 12 in. above grade, includ-
ing normal snow line.
6. Un-insulated single-wall Category IV metal vent
pipe shall not be used outdoors in cold climates for
venting gas-fired equipment without insulation.
7. Through-the-wall vents for Category IV appli-
ances shall not terminate over public walkways or
over an area where condensate or vapor could cre-
ate a nuisance or hazard or could be detrimental to
the operation of regulators, relief valves, or other
equipment.
8. Locate and guard vent termination to prevent acci-
dental contact by people or pets.
9. DO NOT terminate vent in window well, stairwell,
alcove, courtyard or other recessed area.
10. DO NOT terminate above any door, window, or
gravity air intake. Condensate can freeze, causing
ice formations.
11. Locate or guard vent to prevent condensate from
damaging exterior finishes. Use a rust-resistant
sheet metal backing plate against brick or masonry
surfaces.
12. DO NOT extend exposed vent pipe outside of
building beyond the minimum distance required
for the vent termination. Condensate could freeze
and block vent pipe.
U.S. Installations
Refer to the latest edition of the National Fuel Gas
Code.
Vent termination requirements are as follows:
1. Vent must terminate at least 4 ft below, 4 ft hori-
zontally from or 1 ft above any door, window or
gravity air inlet to the building.
2. The vent must not be less than 7 ft above grade
when located adjacent to public walkways.
3. Terminate vent at least 3 ft above any forced air
inlet located within 10 ft.
4. Vent must terminate at least 4 ft horizontally, and
in no case above or below unless 4 ft horizontal
distance is maintained, from electric meters, gas
meters, regulators, and relief equipment.
5. Terminate vent at least 6 ft away from adjacent
walls.
6. DO NOT terminate vent closer than 5 ft below
roof overhang.
7. The vent terminal requires a 12 in. vent terminal
clearance from the wall.
8. Terminate vent at least 1 ft above grade, including
normal snow line.
9. Multiple direct vent installations require a 4 ft
clearance between the ends of vent caps located on
the same horizontal plane.
Canada Installations
Refer to latest edition of B149.1.
A vent shall not terminate:
1. Directly above a paved sidewalk or driveway
which is located between two single-family dwell-
ings and serves both dwellings.
2. Less than 7 ft (2.13 m) above a paved sidewalk or
paved driveway located on public property.
3. Within 6 ft (1.8 m) of a mechanical air supply inlet
to any building.
4. Above a meter/regulator assembly within 3 ft (0.9
m) horizontally of the vertical centre-line of the
regulator.