Gas WH in garage closet

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Mikha'el

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Hi all,

I'm moving my gas-fired WH to a new dedicated closet off the garage - can it sit directly on the garage slab or should I build a platform? The old closet had one, but that was from 1989.
Does the door have to be weather sealed? It will have outside air supply ducting.

Best I can tell, all newer gas water heaters are FVIR and no longer have to be elevated above the garage floor.

I'm in a no-man's land/no AHJ area, but would like to avoid any issues with a home inspection when I sell up.

Thanks,
Michael
 
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Phog

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Even post-FVIR, some people still like to elevate the units off the floor a little to reduce conduction of heat into the slab floor underneath. I doubt this makes much difference personally, but hey who knows. More important than a platform is putting a drip pan underneath. Weather stripping the door or not isn't really relevant to the water heater. The most relevant things for any future home inspection would be the "correct" type of gas and water supply connections (flex vs. hard-piped code requirements vary greatly across the country). And then making sure there is properly sized B-vent & sufficient draft in the chimney flue (for atmospheric-vent models) or properly installed & sloped exhaust (for power-vent / direct-vent models).

Edit: Some places require earthquake straps too.
 
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WorthFlorida

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Elevated on a platform will help should there be a flood event it will keep the burner above the water. Even a few inches can damage the burner unit. If you are in a flood zone, strapping the WH to the wall and elevated will help minimize the WH from being torn out during a flood event. WH are packed with foam insulation and it will float even when filled with water.

Another reason for an elevated gas units was possible gasoline fumes being ignited when installed in a garage. Gas WH in basements always seem to be where the workshop is and opening a can of varnish or having the floor varnish throughout the house lead to several explosions. Vapors from flammable liquids are usually heavier than air so they stays close to the floor where the ignitors were for gas WH's. FVIR was designed and now standard since not everyone put them up in the air.

Weather seal is not necessary since it should have a louvered door for combustion. Installation instructions should address the room requirements.
 

Mikha'el

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Weather seal is not necessary since it should have a louvered door for combustion. Installation instructions should address the room requirements.
Thanks for all the replies.

The closet is on an outside wall, so I was planning to put in high/low vents through the wall - didn't think you could use the garage for a combustion air source. The previous WH closet had vents into the garage attic - now converted to living space.

No flood issues, but I might raise it up a few inches anyway.
 

Jadnashua

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If you lose power, or gas, the WH and lines to it can freeze. The tank itself would take quite a long time to freeze up with the insulation, but the external pipes may not take all that long. If you've got adequate combustion air coming into the closet, that means a fairly significant amount of exterior air, and your standby losses will be higher because those vents won't be insulated.

Personally, if I needed to put the WH in the garage, I'd look into one with closed combustion where it didn't use room air for the burner...it would have two pipes (or one concentric one) to both get exterior combustion air in, and a separate pipe (often can be PVC) pipe to exhaust the air.

Based on the burner size, the device will have a cubic room volume minimum requirement (assumes 'average' leakage), so that it can efficiently run the burner, and might work just fine in the garage depending on how large it is. Except for commercial WH or those larger than a certain size (I think it's 80-gallons), all residential WH today have a burner design that won't explode as the result of volatile gas fumes.

TX can call for a/c a significant amount of time, and while more expensive to buy, you might find a heat pump WH might actually save you some money, and help cool the garage in the process.
 

Sylvan

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The reason is that gasoline vapors are denser than air and hover near ground level.


Keeping the ignition source at least 18" above the floor reduces the chances of igniting gasoline fumes.


The newer water heaters have a flame/vapor safeguard that shuts the burner down
 
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