leaking pressure release valve on old heating system

Discussion in 'Plumbing and Central Heating' started by semi, 22 Jul 2008.

  1. semi

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    I have a 20 year old system in a 3 bed-roomed semi. There is no expansion tank and the boiler is a Baxi WM 531 RS, working perfectly. There is a pressure release valve (1" BSP fitting I think) and it has started leaking. It is fitted on a tee at the return side from the hot water cylinder's heating coil. I can only assume that the expanded water in the system is driven back into the main which I think is now illegal.
    I have no idea who fitted the system, or when the system was fitted.
    A local supplier said he can replace the valve, but would need to know what pressure to get it set to when ordering it. I haven't a clue what that should be!!
    My gut feeling is that an expansion tank should be fitted to turn it into a conventional system, but the easy option is just to replace the valve.

    Any ideas or help would be much appreciated.
     
  2. LUNAT

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    HI


    what is the make ,model of the boiler ?
    and give more details of the system .we will be glad to help. :D
     
  3. DP

    DP

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    The component is most likely to be a pressure relief valve that is set to lift should the boiler 'boil' over as opposed to containing a pressure of 3 bar like on a sealed system. This type of valve is adjusted to a setting that will allow pressure to vent if the boiler thermostat were to fail. This item would be connected to an open vented system.

    If you cannot find the expansion cistern, you might have a single feed primatic HW cylinder that feeds you heating system.
     
  4. heatingman

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    If you definitely do not have a feed & expansion tank, You prob have a primatic cylinder, or even a hydro-spartan unit.
    Can you post a picture of leaking valve?, might be a case or remove and plug off, more info reqd first.
     
  5. semi

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    Thanks for your response.

    The album heating has pictures of cylinder, valve and boiler plate (possibly too small to read).
    The boiler is a BAXI W M 531.R.S G.C number 41-077-01 CAT 2TN.

    There is no expansion tank in the system, and I have not met a system like it before! The cylinder just looks like an old indirect one to me....pretty bad eh!

    Help and comments would be much appreciated as to whether to replace the valve and at what pressure setting, or whether to fit an expansion vessel, or other fix.....

    thanks in anticipation
     
  6. LUNAT

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    HI

    take a picture of the valve and take it to the plumbing merchants they should be able to order another one.
     
  7. semi

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    Hello,

    Thanks for that suggestion, but I did find a merchant who can supply one, but they needed to know what pressure to set it to, and that is something I just don't know.

    cheers
     
  8. D_Hailsham

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    This boiler is so old, it is not listed in the Sedbuk Database. The WM 532RS ceased manufacture in 1981.
     
  9. DP

    DP

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    Does the OP know what a PRV looks like (part number 11346 on BES website). Next question is, has he got this aforementioned PRV fitted to his system or is it something entirely different?

    I very much doubt the Baxi boiler would have a PRV that lifts at 3bar let alone boiler being suitable for a sealed system.

    If you go to BES website and carry out a search for spring safety valve (part 7512), chances are this is what you have.

    I wonder if this supplier of "adjusted" valve isn't taking you for a ride.

    Once you get the valve (that supplier does not know what it looks like and you don't know what you are going to get), you still have a task of replacing the item. I think that will be an even bigger stumbling block for you. Please do not be offended. My assumption is based on kind of questions you are asking.
     
  10. holty

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    does the prv have a mushroom type cap with holes around. it or does it look like it has a lever on it.
     
  11. semi

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    yes it has a mushroom type cap with holes round it. A photo of it is in my album named heating system, and yes the system is pretty old.

    No I'm not offended by folks comments at all, just pleased for any help.
     
  12. mickyg

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    looks like this guy nailed it early on. To be honest I don't think these valves are an essential part of the system. I've had them leaking on "normal" open vent systems and just plugged them with a brass plug. I'm not 100% about your primatic system but if it were me I would plug it :D
     

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