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Old 01-26-2006, 11:18 AM   #1
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1975 27' Overlander
Nelson , BC
Join Date: Sep 2005
Posts: 2
Unhappy Leaking Hot Water Tank or tap?


As you can see in this photo the tap above the water heater on my 75 Overlander is leaking water. We were hooked up to the city water all night. Only this morning ( about a half-hour or so after I started the water heater) did the leaking start.

Can you tell me what's broken here and how best to fix it?

We're hooked up to city water. I've turned the hot water heater off until


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Old 01-26-2006, 11:46 AM   #2
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1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
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Originally Posted by hubrik
Can you tell me what's broken here and how best to fix it?
The valve that is leaking is a combination thermal/overpressure relief.

You may want to try to lift the little lever on the top to a full open position (with the city water connected) - it is possible that a bit of trash has been lodged under the seat. By opening the valve all of the way and letting some water run through it (about a quart will do) you might luck out and flush the trash out of the seating area.

If that does not work a replacement valve should be available.

They normally sell for less than $20US.

Getting them out is sometimes a real bear.

Luck - Please post back how your repair went.


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Old 01-26-2006, 01:03 PM   #3
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1970 31' Sovereign
Portland , OR
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You might try turning down the heater's thermostat. I have an old one that is finicky, and it get's too hot and overflows. Altitude may be a factor.
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Old 01-26-2006, 04:46 PM   #4
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1992 29' Excella
madison , Wisconsin
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before you do any of the above completely drain the water heater and refill it. shut off the water and remove the drain plug. then turn the water back on after replacing the plug.

this will restore the air bubble in the unit and may function normally again. without the air bubble to allow for expansion the t and p valve will leak as you have shown.

when water is left in a rv heater over long periods the air bubble is absorbed by the water as it heats. consult your manual.

you call them ferrets, i call them weasels.
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Old 01-26-2006, 06:03 PM   #5
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1991 34' Excella
Mansfield , Texas
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If you can tap on with a hammer while it is under pressure, with the water heater is off, and it doesn't stop [ replace it.] These are relatively cheap. Try all of the above, then go buy a new one. Home Depot or other home improvement stores stocks all types. Just make sure the size and the temperature are the same.
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Old 01-27-2006, 01:04 PM   #6
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1967 26' Overlander
Huntsville , Alabama
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Originally Posted by hubrik
... Can you tell me what's broken here and how best to fix it? ...
While John HD posted the best starting point, there may be nothing wrong, OR your water heater's overpressure relief valve (OPR) may be bad, OR your cold water supply's OPR valve may be bad OR your regulator may be bad.

Assuming ALL Airstreams are as well built as mine, your shore water plumbing will include, after the shore line, a check valve, a cold water OPR, regulator, and then the water heater's OPR. The water heater's OPR is designed to vent when either the pressure or temperature is too high. The cold water OVP works on pressure alone.

Your water heater, when in operation, will raise the pressure in both the cold water & hot water lines. With a functional check valve, this pressure can not exit through the shore water hose. It has to go somewhere. Ever notice turing a faucet on & the water coming out fast at first then quickly returning to normal? That is pressure caused by heating water.

If there is an air bubble (desired) in the water heater, it will compress & absorb most of the excess pressure. But if your regulator is either misadjusted or not seating well, your lines may have too much pressure if the shore water's supply pressure is high. Or, as John indicated, you might be out of air.

It is possible that your cold water OPR used to be venting this pressure, and has now stopped for some reason.

Start with John's remedy first.


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