Minimum clearances for gas fired appliance vents

I have two gas fired 50,000 plus btu high efficiency water heater side wall vents that terminate 8’ below an operable window. All located at a front entry overhang of a home. It all looks a little suspect to me. Is this allowed?

National Fuel Gas Code, ANSI Z223.1/NFPA 54, 7.3.4e and 7.8a,b, as follows:

  1. The exit terminals of a mechanical vent system shall be not less than 7 feet (2.13 m) above grade when located adjacent to public walkways, see Figure 16.
  2. Aventingsystemshallterminateatleast3feet(0.91m)aboveany forced air inlet located within 10 feet (3.1 m), see Figure 16.
  3. The venting system shall terminate at least 4 feet (1.2 m) below, 4 feet (1.2 m) horizontally from or, 1 foot (0.31 m) above any door, window or gravity air inlet into any building.

The chart reads 6” to 36” depending on the BTU. Does this include directly below the window?

:+1 Thanks for the information guys

From my understanding the BTU has no bering on the requirement for being directly below (or in my opinion on any requirement in direction). Below is below no matter how you look at it. Some more experienced guys might have a more reputable opinion.

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No problem. I appreciate the insight. My thought was that there might be a difference, due to the hot gas exhaust traveling upward but maybe there is no difference. I just make note of the location and recommend they confirm clearances.

Not for nothing, but the AO Smith install manual clearly lists the clearances and venting requirements. They also include a handy diagram for illustrative purposes.

You can (and should) confirm the clearances by referring to the appliance manufactures listed installation guide.



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^^^^ when in doubt always refer to manufacturer specs