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  1. #1
    Join Date
    Feb 2003
    Location
    Belgium
    Posts
    1,643

    Default Leaking Pressure Relief Valve

    The PRV on my water heater has developed an annoying leak, which causes the pump to cycle far too often.
    Any ideas what I could do? Would soaking it in vinegar help?
    Or should I just condemn and replace it? If so, can I use a spare that I buy at the plumbers?

  2. #2
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    43,052

    Default Re: Leaking Pressure Relief Valve

    Quote Originally Posted by westhinder View Post
    The PRV on my water heater has developed an annoying leak, which causes the pump to cycle far too often.
    Any ideas what I could do? Would soaking it in vinegar help?
    Or should I just condemn and replace it? If so, can I use a spare that I buy at the plumbers?
    It may be a temperature and pressure relief valve.

    If you replace it you will need to get one with the same pressure (and temperature) ratings
    Last edited by VicS; 23-04-19 at 21:56.

  3. #3
    Join Date
    Sep 2001
    Location
    Me - Zumerzet Boat - Wareham
    Posts
    11,850

    Default Re: Leaking Pressure Relief Valve

    If it will strip down, you can clean it and see if that solves the problem. Nothing to loose and you gain a bit of knowledge.
    MontyMariner.co.uk
    Facilitated by AWESEM WP Agency

  4. #4
    Join Date
    Jul 2006
    Posts
    4,646

    Default Re: Leaking Pressure Relief Valve

    You are supposed to turn the relief knob occasionally - when I fitted a new one as old was leaking the instructions on the new one said monthly, to keep the valve face clean. This is on a temp and pressure valve from ASAP.

  5. #5
    Join Date
    May 2007
    Location
    Nidderdale
    Posts
    41,486

    Default Re: Leaking Pressure Relief Valve

    Quote Originally Posted by westhinder View Post
    The PRV on my water heater has developed an annoying leak, which causes the pump to cycle far too often.
    Any ideas what I could do? Would soaking it in vinegar help?
    Or should I just condemn and replace it? If so, can I use a spare that I buy at the plumbers?
    It depends why it is leaking. If might be faulty, it might also be releasing excessive pressure as intended. A spare must have the same pressure ( and possibly temperature as mentioned) specification as the original to be safe, but in principle you can buy a spare at the plumbers merchants. Don't be tempted to fit one with a different rating. Some of these PRVS can be dismantled and the seating cleaned and sprung diaphragm examined for damage. It depends which one as not all of them come apart.

  6. #6
    Join Date
    Jun 2001
    Location
    Dover
    Posts
    5,279

    Default Re: Leaking Pressure Relief Valve

    PRV's aren't expensive, so as mentioned above if its a standard type you can get a spare at many plumber's merchants. (Not worth trying to fix). Pick one that operates above the upper (cut-out) pressure of your pump, bearing in mind the safety limit of your calorifier. If you have a 40 psi pump and a 37 psi PRV - yes, it's going to leak!

    While it could be the PRV itself, it is just as likely to be a problem with the pump. I've known them getting considerably above their rated cut-out pressure. With the popular Jabsco type there is a pressure adjustment screw which you might experiment with - see the manual.

    Also check your expansion tank. The symptom of low pressure there is a very jerky cut in and out of the pump which puts an extra load on both the pump and the PRV, often resulting in leaks and pump failure. If the expansion tank isn't working at all, then when water is heated and expands in the calorifier it has nowhere to go except out through the PRV. The expansion tank should be pressured to just below the cut-in pump pressure. Expansion tanks do need replacing from time to time.

    Finally, do you have a non-return valve fitted to your hot water system? This is quite common. If so you must also have an accumulator (secondary expansion tank) fitted and working next to the calorifier to cope with water expansion. The accumulator should be pressured above the cut-out pressure of the pump but below that of the PRV.

    P.S. The temperature sensor of the PRV, if you have one, is a bit of a luxury, and these are anyway often unreliable. It is OK to use a replacement without one.
    Last edited by AndrewB; 24-04-19 at 09:34.

  7. #7
    Join Date
    Feb 2003
    Location
    Belgium
    Posts
    1,643

    Default Re: Leaking Pressure Relief Valve

    Thank you all for your advice.
    I will check the cut out pressure on the pump that i replaced last year, and look for a new PRV with the correct specifications. At nearly 20 years of age I suppose replacing it is in order.

  8. #8
    Join Date
    Nov 2008
    Posts
    6,779

    Default Re: Leaking Pressure Relief Valve

    The actual valve costs about a fiver. When I wanted to replace mine last winter, I found that it also incorporated a drain screw. I thought that seemed like a good idea, but couldn't get an exact replacement, so fitted a Tee piece with a drain cock between the PRV and the calorifier. It makes it easy to drain the calorifier to protect from winter frost damage.

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