Turned on my Atwood 6 gal gas water heater yesterday to heat water for the day and about 15-20 minutes later I had water leaking under bathroom sink cabinet which is almost directly over the heater. Shut it off, dried up the water on the floor and no more leak. No leaks when turning on hot or cold water faucets so the water lines don't leak. Only leaks when heating up. No leaks or drips outside under the heater or coach, so it only leaks UP into cabinet under sink, which I have no access to. Any ideas? Will the heater have to be removed for examination?The top of the tank is about 10" below floor level of the coach and if the hot cold feeds don't leak when turned on, what other line is running up from the heater that could be leaking ?Appreciate any ideas or comments. Thanks!

Maybe the PT valve is bad and the overflow pipe is leaking. Just a guess.

ezgoin wrote:Will the heater have to be removed for examination?Yes. Not difficult but does take a bit of time. Assuming the water line fittings themselves aren't the source of the problem the aluminum tank itself is either split or there could be a hairline crack in the welds where the water lines connect to the tank. I helped a friend remove his Atwood water tank with this exact issue, fortunately in his case the hairline crack was successfully welded. If in your case you determine that welding isn't practical the good news is that Atwood does sell replacement tanks, with Suburban you'd have to replace the entire water heater. BTW, in the process of removing the tank you'll destroy the gaskets and rings that hold the tank in place to the mounting plate ... new replacement tanks include this ring & gasket kit but if you manage to repair your original tank this ring & gasket kit can be ordered from any RV dealer.

I'm still learning, but I would be hard to convince that a leak in the tank itself would go up......some how get thru the floor, and show up under the sink, and not leak downward and show up at the bottom of the RV and on the ground. I mean, wouldn't that completely defy the law of gravity ?? What am I missing ?

With the system all closed and under a slight pressure from the pump, as the water in the tank heats up the expansion puts the entire water system under MUCH MORE pressure.This goes back to "normal" once a faucet is opened.The weak spot in mine is the pressure relief valve mounted on the heater tank (old valve and new one both).It would appear that the extra pressure has found a different weak spot on yours. Hopefully a few experiments can find where the leak is actually coming from......and it probably is NOT at the water heater itself.

Atwood gas water heater leaks when turned on | Good Sam Community

12 Replies

ezgoin
Explorer
Sep 28, 2016
Re-establishing the air gap took care of my problem. No more leak. What would I do without all the info and help I've received in these forums? Thank You to everyone who contributes.

Bill
jplante4
Explorer II
Sep 26, 2016
From 4 years ago

Airgap

Motley on the air gap

And someone just started another thread on the same topic here
Sam_Spade
Explorer
Sep 26, 2016
RJsfishin wrote:
Maybe a little off topic, but isn't the air that is supposed to be at the top of the tank, suppose to absorb that expansion pressure ?

Not off topic at all.
I see no evidence that mine HAS any dead air at the top of the hot water tank. Indeed a household HW tank draws out of the very top.
But I keep seeing people mention this so I have to assume that those built for RVs work a bit differently.
ezgoin
Explorer
Sep 25, 2016
I opened the pressure valve on cold water heater and water comes out. Do I hold it open until the water stops?
John_Wayne
Explorer II
Sep 25, 2016
Try opening the pressure relief valve and re- establish The air space needed in the heater. It may stop the leak.
ezgoin
Explorer
Sep 25, 2016
Sam Spade wrote:
Hopefully a few experiments can find where the leak is actually coming from......and it probably is NOT at the water heater itself.

I am leaning this way right now. The water heater sits 10-12" below coach floor, so I'm assuming the leak must be from a connection under the sink cabinet caused by the pressure created by heating the water. (No water leaks out from under the cabinet with the heater off, not even when using the sink.) Problem is...how do I access any plumbing connections hidden under the cabinet. Directly under the sink where the lines come up are boxed in with no way to look underneath and next to the sink are drawers that have a wall between them and the sink. ?????
RJsfishin
Explorer
Sep 25, 2016
Maybe a little off topic, but isn't the air that is supposed to be at the top of the tank, suppose to absorb that expansion pressure ?
And that not to mention the little bladder expansion tank that I have added to every RV I have ever had. I never have expansion pressure while the water is heating.

Sam Spade wrote:
With the system all closed and under a slight pressure from the pump, as the water in the tank heats up the expansion puts the entire water system under MUCH MORE pressure.

This goes back to "normal" once a faucet is opened.
The weak spot in mine is the pressure relief valve mounted on the heater tank (old valve and new one both).

It would appear that the extra pressure has found a different weak spot on yours.

Hopefully a few experiments can find where the leak is actually coming from......and it probably is NOT at the water heater itself.
Sam_Spade
Explorer
Sep 25, 2016
With the system all closed and under a slight pressure from the pump, as the water in the tank heats up the expansion puts the entire water system under MUCH MORE pressure.

This goes back to "normal" once a faucet is opened.
The weak spot in mine is the pressure relief valve mounted on the heater tank (old valve and new one both).

It would appear that the extra pressure has found a different weak spot on yours.

Hopefully a few experiments can find where the leak is actually coming from......and it probably is NOT at the water heater itself.
RJsfishin
Explorer
Sep 25, 2016
DP
RJsfishin
Explorer
Sep 25, 2016
I'm still learning, but I would be hard to convince that a leak in the tank itself would go up......some how get thru the floor, and show up under the sink, and not leak downward and show up at the bottom of the RV and on the ground. I mean, wouldn't that completely defy the law of gravity ?? What am I missing ?

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Atwood gas water heater leaks when turned on

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