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  1. #1
    Join Date
    Feb 2010
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    2

    Exclamation Leaking Pressure Relief Vavle on Water Heater

    We bought our home in November of 2008 in Somerset MA. Since then we've done a lot of remodeling.

    I had a plumber come in (who has a master license) and plumb the remodeled bathroom and ad some lines for a fridge.... etc.

    From day on we had low water pressure in the house. So he suggested that we have the line replaced from the house to the shutoff... so we did, and since we did that the town comes in and replaces the main from the shutoff to the street.

    At the same time he had noticed that the pressure relief valve on the water heater was always leaking, so he suggested getting a brand new water heater. Which we did.

    He came in and put a brand new water heater in and the pressure relief valve on the brand new water heater started leaking just as the old one did. So he put another brand new pressure relief valve on the brand new water heater and did that 3 times before he figured it has to be something else.

    He then went to the water meter and noticed a pressure regulator and said that could be the problem. He took that apart, cleaned it all out and then put it back into place.

    As you would guess... the pressure relief valve on the water heater is still leaking.

    In his 20 + years of doing plumbing still has no idea what the problem could be. He did all that work in January of 2009 and we've just been putting buckets under that pressure relief valve and emptying it on occasion.

    I've called the town to see if they have any idea of what the problem could be and the guy told me that our neighborhood has average 60lbs of water pressure and he has never heard of anything like this before and has no suggestions.

    Please help....

  2. #2
    Join Date
    Jan 2010
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    163

    Default Re: Leaking Pressure Relief Vavle on Water Heater

    It may be that when the new water service line was installed, a new meter was intalled with a check valve. A check valve is a one-way valve that can make your house system a "closed" system--that is, there's no way for excess pressure that is created inside your house to push its way back out into the mains.

    Excess pressure can be caused by the water heater. What happens is that when the tank heats up, the water expands, and if this happens at times when no one opens a faucet in the house, the expanded water has no place to go, except by escaping at the relief valve of the water heater. It will drip a small amount and then stop. Water will not compress the way air does.

    This would likely happen at night after the hot water has been used for the last time of the day, and the water heater re-heats with the resulting expansion of water.

    If this is what's happening, it should be corrected by the installation of an expansion tank by the water heater. It is simply a small tank about the size of a 5-gal. bucket that has an air chamber within itself. The air will compress and accept the expanded water without causing the pressure relief valve to open. Repeated opening and and dripping of the relief valve can lead to a build-up of scale and corrosion in its seat, which can cause it to eventually seal closed, and this creates a danger of WH explosion if the WH continues to heat beyond its safe temperature.

  3. #3
    Join Date
    Feb 2010
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    2

    Default Re: Leaking Pressure Relief Vavle on Water Heater

    I did notice that when I took a long hot shower and immediately went to the water heater after the shower it was continuously leaking from the pressure relief valve.

    I don't think they changed out the water meter when they replaced the main service line.

  4. #4
    Join Date
    Jan 2010
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    163

    Default Re: Leaking Pressure Relief Vavle on Water Heater

    Quote Originally Posted by dsrcti View Post
    I did notice that when I took a long hot shower and immediately went to the water heater after the shower it was continuously leaking from the pressure relief valve.

    I don't think they changed out the water meter when they replaced the main service line.

    Even so, you may be onto something with what you noticed about the drip happening during the WH's heating cycle.

    You can test by shutting off the WH during the night, and checking in the morning to see if there's a sign of dripping.

  5. #5

    Default Re: Leaking Pressure Relief Vavle on Water Heater

    I would bet money you need an expansion tank. It sounds like you have a closed system and when the water heater heats a significant amount of cold water it creates excess pressure.
    Causes of a leaky pressure relief valve
    Plumbing and Heating Tech.
    My plumbing website Hidden Content

  6. #6
    Join Date
    Feb 2010
    Location
    South*East
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    1,168

    Default Re: Leaking Pressure Relief Vavle on Water Heater

    You need a expansion tank. That makes three.

    John

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