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Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
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* Reference: The National Fuel Gas Code 2009 Edition
*NOTE: Armstrong Hot Water, Inc.
recommends a minimum clearance
of 4 feet (1.2m) where the exhaust
plume caused by the unit may obstruct
views or affect the cosmetic look of the
building. In canada, there is a minimum
clearance of 10 feet (3m).
Through-the-Wall Vent Termination
1. A through-the-wall mechanical draft venting system shall terminate at least 3 ft (0.9 m) above any forced air inlet located
within 10 ft (3 m).
Exception No. 1:
This provision shall not apply to the combustion air intake of a direct vent appliance.
Exception No. 2:
This provision shall not apply to the separation of the integral outdoor air inlet and flue gas discharge of
listed outdoor appliances.
2. A through-the-wall mechanical draft venting system of other than direct vent type shall terminate at least 4 ft (1.2 m) below,
4 ft (1.2 m) horizontally from, or 1 ft (300 mm) above any door, operable window, or gravity air inlet into any building. The
bottom of the vent terminal shall be located at least 12 in. (300 mm) above finished ground level.
3. The through-the-wall vent terminal of a direct vent appliance with an input of 10,000 Btu/hr (3 kW) or less shall be located at
least 6 in. (150 mm) from any air opening into a building, an appliance with an input over 10,000 Btu/hr (3 kW) but not over
50,000 Btu/hr (14.7 kW) shall be installed with a 9 in. (230 mm) vent termination clearance, and an appliance with an input
over 50,000 Btu/hr (14.7 kW) shall have at least a 12 in. (300 mm) vent termination clearance. The bottom of the vent terminal
and the air intake shall be located at least 12 in. (300 mm) above finished ground level.
Venting - continued
Figure 4.1