Venting Under a Porch-National Code Reference

I finally broke down and bought a direct vent tankless water heater to overcome the combustion problem I was facing with the standard power vent model I own. At any rate, I find myself in need of venting the heater under a 7' unenclosed entry porch. I'm looking for a national code reference that addresses clearance under a porch. I searched ANSI Z223.1/ NFPA 54, but I couldn't find anything. Canadian code requires 1' clearance from the porch and, I believe, two unenclosed sides. I'm looking for something that will convince my local inspector that this is an acceptable location for the termination.

National Fuel Gas Code 12.3.5....direct vent appliances shall be installed in accordance with manufacturer's instructions..and with 12.9.3, which says for up to 50,000 BTU, vent terminal shall not be within 9" of any opening into the building.


That's all I can find. Can not find specifics about under the porch. Check with the mfg.

Thanks. I'll bring the 9" clearance thing to the inspector. The manufacturer (Takagi) has guidance for Canada (12" clearance from the deck), but says to defer to local guidance in the US. *update* The inspector bought off on the vent under the porch.

Noth Jersey said:

... says to defer to local guidance in the US.

Click to expand...

And thus the buck is passed.