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8.1 Venting
This heater must be vented in accordance with the
rules contained in this manual and with the following
national codes and any state, provincial or local
codes which may apply:
United States: Refer to National Fuel Gas Code
NFPA 54/ANSI Z223.1 - latest revision.
Canada: Refer to Natural Gas and Propane
Installation Code CSA B149.1 - latest revision.
Exhaust end of heater will accept a 4" (10 cm) vent
pipe using the vent adapter (P/N 90502700). To
prevent leakage of condensation, install the vent
adapter with the seam on top and seal the joint using
a high temperature silicone sealant.
Any portion of vent pipe passing through a
combustible wall must have an approved thimble
to conform with the above listed codes.
Vent pipe must be sloped downward away from the
burner 1/2'' (1 cm) for every 20' (6 m).
The heater may be individually vented or common
vented. When venting horizontally, a maximum of two
heaters can be commonly vented. See Page 33,
Section 8.9. When venting vertically, a maximum of
four heaters can be commonly vented. See Page 34,
Section 8.10.
The heater may also be installed unvented in certain
circumstances according to building ventilation codes.
Refer to the above codes and Page 31, Section 8.2 for
further information. Unvented operation also requires
compliance with the clearances to combustibles given
on Page 8, Figure 12.
The bottom of the vent or air intake terminal shall not
be located less than 1' (.3 m) above grade level.
The vent shall not terminate less than 7' (2.1 m) above
grade where located adjacent to public walkways.
Vent terminal must be installed at a height sufficient to
prevent blockage by snow and building materials
protected from degradation by flue gasses.
Secure all joints with #8 x 3/8 sheet metal screws.
Seal all joints with high temperature silicone sealant.
Vent terminal must be beyond any combustible
8.1.1 United States Requirements
Vent must terminate at least 3' (.9 m) above any forced
air inlet located within 10' (3.1 m).
Vent must terminate at least 4' (1.2 m) below,
4' (1.2 m) horizontally from, or 1' (.3 m) above any
door, operable window, or gravity air inlet into any
8.1.2 Canadian Requirements
The vent shall not terminate within 6' (1.8 m) of a
mechanical air supply inlet to any building.
The vent shall not terminate within 3' (.9 m) of a
window or door that can be opened in any building,
any non-mechanical air supply inlet to any building, or
of the combustion air inlet of any other appliance.
8.2 Unvented Operation
Sufficient ventilation must be provided in the amount
of 4 cfm per 1000 Btu/h firing rate (United States); 3
cfm per 1000 Btu/h firing rate (Canada).
Use of optional outside combustion air is not
recommended with unvented heaters.
If exhaust fans are used to supply ventilation air, an
interlock switch must be used to prevent the heater
from coming on when the fans are off. This may be
done using a pressure switch.


Carbon Monoxide Hazard

Heaters installed unvented must be interlocked

with sufficient building exhaust.

Heaters must be installed according to the

installation manual.

Failure to follow these instructions can result

in death or injury.


Cut/Pinch Hazard

Wear protective gear during installation,

operation and service.

Edges are sharp.

Failure to follow these instructions can result

in injury.