Please Help - Water Heater Vent Issue


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Old 06-01-12, 04:41 PM
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Please Help - Water Heater Vent Issue

Two weeks ago I installed a new GE gas water heater. I have 1" of fall per foot of vent pipe (2 feet total) and the chimney is clear. All seams on the vent pipe are sealed with foil tape. The heater is not venting properly. Twice now, the top of the water heater has become so hot that the blue and red plastic pieces marking the water lines have melted filling the house with the smell of burning plastic. The pipe insulation on the hot water line has also melted. Both times this has occured it has been raining outside.

My HVAC friend's only thought was that perhaps I need a chimney liner. I thought this odd since I did not require a liner with the old Whirlpool water heater. My friend theorized that the lower barometric pressure present during rainy weather is making it hard to draft and that the new heater may not generate the heat that old model did. A 3" chimney liner would heat faster.

So, any thoughts? Anyone else encountered this problem? I'd rather get some other opinions before jumping into this chimeny liner.

Thanks!
 
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Old 06-01-12, 05:15 PM
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I have 1" of fall per foot of vent pipe...
Did you mean to write rise rather than fall? The vent should rise slightly (maybe 1/4 inch per foot minimum) from the water heater outlet to the chimney connection. You also need a 12 inch vertical piece of vent piping directly out of the water heater draft hood. This means that in your case the chimney connection needs to be a minimum of 12-1/2 inches above the top of the water heater vent hood.

This IS a natural draft water heater isn't it and not a power draft unit?
 
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Old 06-01-12, 05:20 PM
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Yes, I did mean rise. A 12" vertical pipe off the top of heater? That I do not have, nor have the two previous heaters had it. An elbow comes right off the draft hood. Only way I could make that happen is to put another hole in the chimney.

Yes, it is a natural draft water heater.
 
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Old 06-01-12, 06:13 PM
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I would ask what is the total height of the masonary chimney, and the clay liner dimensions?

Furd is correct I believe that the code states 12" minimum verical pipe is needed off the heater before any turn.

How many btu is the heater?

And the new code is 4" flue for the heater. Did you still use the old 3"?

Before hooking up the flue to the chimey was it inspected for fallen debris, such as broken tiles?

Last but not least, is it possible you stuck the smoke pipe from the heater too far in the chimney so its hitting the back and blocking the draft?

Oh one more thing. Get a CO detector before someone dies, and please take out a permit if you have not already done so. Its for your protection.

This is where a pro is needed and a friend with theories is pretty useless IMO.

Mike NJ
 

Last edited by lawrosa; 06-01-12 at 08:08 PM.
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Old 06-01-12, 07:50 PM
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Masonry chimney goes from basement to roof of 2 story house, so 3 stories + attic, not sure of exact height. Without being on the roof, I'd guess the clay liner is approx 12 x 8.

A 12" vertical will be difficult, a new hole will need to be cut in the chimney.

36K BTU

I used a 4" flu pipe.

Chimney was inspected from top and bottom, all clear.

Smoke pipe is not inserted too far in the chimney.

We have a CO detector in place.
 
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Old 06-01-12, 08:10 PM
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Anything else feed this chimney?

Mike NJ
 
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Old 06-02-12, 06:04 AM
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I believe my gas furnace exhausts in this chimney.

I'm looking into drilling a new hole in the chimney to add a 12" riser to the top of the furnace.

I'm struggling understanding the problem, b/c the only thing that changed in the set up is the water heater. The previous heater never had an exhaust issue. Also, the exhaust problem only seems to occur when it's raining. I just don't get it...
 
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Old 06-02-12, 08:06 AM
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Confirmed this morning that this issue only occurs during poor weather. Sunny, nice day outside so kicked the water heater on this morning. Venting perfectly, top of heater not even warm to touch. Only the vent/flu is hot to touch.
 
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Old 06-02-12, 08:33 AM
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Mr. Water Heater did not have any ideas. Said that if there is a downdraft it should be consistent, not dependent on weather.
 
 

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