Raypak AVIA 264A Installation And Operation Manual page 14

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
combustible materials. Use insulated vent pipe spacers
where the vent passes through combustible roofs and
walls.
Vent Terminal Location
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 damage 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 condensate 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. (305 mm) above grade,
including normal snow line.
6. Un-insulated single-wall metal vent pipe shall not be
used outdoors in cold climates for venting gas-fired
equipment.
7. 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 detrimental
to the operation of regulators, relief valves, or other
equipment. Where local experience indicates that
condensate is a problem with Category I and III
appliances, this provision shall also apply.
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 the
vent pipe.
14
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 (1.2 m) below, 4 ft
(1.2 m) horizontally from or 12 in. (305 mm) above
any door, window or gravity air inlet to the building.
2. The vent must not be less than 7 ft (2.1 m) above
grade when located adjacent to public walkways.
3. Terminate vent at least 3 ft (0.9 m) above any forced
air inlet located within 10 ft (3.0 m).
4. Vent must terminate at least 4 ft (1.2 m) horizontally,
and in no case above or below, unless a 4 ft (1.2
m) horizontal distance is maintained from electric
meters, gas meters, regulators, and relief equipment.
5. Terminate vent at least 6 ft (1.8 m) away from adjacent
walls.
6. DO NOT terminate vent closer than 5 ft (1.5 m) below
roof overhang.
7. The vent terminal requires a 12 in. (305 mm) vent
terminal clearance from the wall.
8. Terminate vent at least 12 in. (305 mm) above grade,
including normal snow line.
9. Multiple direct vent installations require a 4 ft (1.2 m)
clearance between the ends of vent caps located on
the same horizontal plane.
Canadian Installations
Refer to latest edition of the B149 Installation code.
A vent shall not terminate:
1. Directly above a paved sidewalk or driveway which
is located between two single-family dwellings 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 (915
mm) horizontally of the vertical centerline of the
regulator.
5. Within 3 ft (0.9 m) of any gas service regulator vent
outlet.
6. Less than 12 in. (305 mm) above grade level.
7. Within the 3 ft (915 mm) of a window or door which
can be opened in any building, any non-mechanical
air supply inlet to any building or the combustion air
inlet of any other appliance.
8. Underneath a veranda, porch or deck, unless the
veranda, porch or deck is fully open on a minimum of
two sides beneath the floor, and the distance between
the top of the vent termination and the underside of
the veranda, porch or deck