air supply for gas water heater


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Old 07-07-11, 02:27 PM
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air supply for gas water heater

I'm not sure if this is the right place for this. Our water heater is in the garage. On the door, going to the outside(not the garage door for the car), there isn't a threshold, and I know bug and spiders are comming into the garage, and when it is windy, leaves and stuff come inside. I wanted to put a threshold in, but I am worried that there isn't enough air supply in the garage for the gas water heater. There isn't a vent from the garage going to the outside. I know both of my parents houses have vents in the stucco for the garage. All of the houses were built from 99-02. So I cant imagine too much of change in codes. There is a exhaust vent for the water heater, so is that enough to replenish the air?? Our neighbor next door, has a thershold, the neighbor on the other side doesn't have a door, nor a vent. All of the water heaters are in the garage.

I just don't want to cause CO or any other problems due to the lack of air.
 
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Old 07-07-11, 03:54 PM
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If the exhaust is a triple wall pipe, there is fresh air coming back in on the outer casing for combustion. Put the threshold in. Garage doors are loose enough to allow enough air in for combustion as well. If you want a warm and fuzzy, you could install 4" round screened soffit vents in the wall adjacent to the water heater. For example only: bestlouver : Round Soffit Vents
 
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Old 07-08-11, 09:38 AM
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I think your going about your issue wrong. Regular air infiltration is good enough in a large enough space.

Use this as a guideline but check your local code it should be the similar.

"Where the volume of the space in which fuel-burning appliances are installed is greater than 50 cubic feet per 1,000 Btu/h (4.83 L/W) of aggregate input rating in buildings of ordinary tightness, insofar as infiltration is concerned, normal infiltration shall be regarded as adequate to provide combustion air."

Example:

So if your HWH was 40,000 btu X 50 cu ft per 1,000 btu = 2,000 cu ft of space would be the min.

How big is your garage?

Lets say 25 L x 15 W x 10 H = 3700 cu ft. No air vents required.

Hope this helps.

Mike NJ
 
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Old 07-09-11, 11:48 AM
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Thanks all. I checked the California Code and its the same 50 cu ft. per 1,000 BTU's. I'll measure the garage and see if I need a vent or not. Thanks all!
 
 

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