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Author Topic: Water Heater pop-off valve leak  (Read 7196 times)

LK23

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Water Heater pop-off valve leak
« on: February 20, 2009, 04:20:05 PM »
I have a small drip coming from the outlet of the water heater pop-off valve.  I assume I need to replace the valve.  Is this a standard valve that can be purchased at Home Depot or Lowes?  Or, do I need to go to a RV supply store?
2005 Itasca Horizon 40AD

Ron

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Re: Water Heater pop-off valve leak
« Reply #1 on: February 20, 2009, 04:53:06 PM »
Very likely you have lost the air that is required for expansion and thus when the water expands the pop off valve does its job.  Try reestablishing the air head.  This can be accomplished by letting the water cool and with the water supply turned of open the popoff valve manually and let the water drain out till it stops.  Another way is to drain the tank part way with the water supply turned off then reinstall the plug and turn the water supply on.  Open a hot water tap and let it run till no more air is present.  This should fix your problem.
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SargeW

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Re: Water Heater pop-off valve leak
« Reply #2 on: February 20, 2009, 05:36:01 PM »
Ron is exactly right.  However, in the off chance that replacement is required, it is a standard pressure relief valve available at any hardware store.

Sarge
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LK23

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Re: Water Heater pop-off valve leak
« Reply #3 on: February 20, 2009, 08:00:07 PM »
Thanks for the replies.  Winnebago customer support suggested the same thing.  Following their advice I turned off the water pump, opened the the pop-off valve and ran a inside faucet to create a air pocket.  The leak stopped for awhile and is now back.

Help me understand the concept.  The water will leak out but not air.  That doesn't make sense to me.
2005 Itasca Horizon 40AD

Ron

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Re: Water Heater pop-off valve leak
« Reply #4 on: February 20, 2009, 08:20:57 PM »
Thanks for the replies.  Winnebago customer support suggested the same thing.  Following their advice I turned off the water pump, opened the the pop-off valve and ran a inside faucet to create a air pocket.  The leak stopped for awhile and is now back.

Help me understand the concept.  The water will leak out but not air.  That doesn't make sense to me.

Air is compressible while water is not.  With just water in the tank the pressure on the valve is much more when the water heats up due to expansion so the valve operated as dedigned and releases the excess pressure.  With some air in the tank it can compress when the water expands therefore the valve is not exposed to the extreme pressure it was with just water in the tank.   Try drains more water out of the tank via the drain plug as I described in the second option.
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Alaskansnowbirds

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Re: Water Heater pop-off valve leak
« Reply #5 on: February 20, 2009, 11:04:26 PM »
If you have to replace the valve be sure you get the right thread size. They come in both 1/2 & 3/4 inch. Don't ask me how I know.  ;D
Don & Peg
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LK23

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Re: Water Heater pop-off valve leak
« Reply #6 on: February 20, 2009, 11:26:06 PM »
Ron,

Thanks, that finally makes some sense.  I will try again to get some air in the top of the water heater.  I don't want to remove the drain plug since I seem to have "a thing" going with that plug and the right amount of teflon tape to keep it from leaking.
2005 Itasca Horizon 40AD

Ron

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Re: Water Heater pop-off valve leak
« Reply #7 on: February 21, 2009, 12:08:05 AM »
If you have to replace the valve be sure you get the right thread size. They come in both 1/2 & 3/4 inch. Don't ask me how I know.  ;D
Now that sounds like experience.
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Ned

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Re: Water Heater pop-off valve leak
« Reply #8 on: February 21, 2009, 07:15:11 AM »
The household sized valve sells for <$10, the RV sized valve is >$20.  Don't ask me either :)
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

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