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Vaillant EcoTEC plus 831 pressure keeps rising

Discussion in 'Plumbing and Central Heating' started by As2215, 16 Jan 2018.

  1. As2215

    As2215

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    I would appreciate any advice/help please

    I have a Vaillant EcoTEC plus 831 boiler. I changed a radiator recently following a leak and the next day found the pressure on my boiler rising to 3.0

    Engineer came out checked the pressure on expansion vessel and pumped it up. Next day pressure had risen again. Engineer returned and changed the expansion vessel. Problem still there. He then changed the filling loop grey knobs but problem still there. After speaking to Vaillant he has now changed the heat exchange plate. But the problem is still there.

    The pressure gradually goes up over several hours, even when there is no heating or hot water being used.

    I am completely confused now as is the engineer as he has checked all the parts including prv and diverter valve.

    Any ideas please???
     
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  3. terryplumb

    terryplumb

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    Did he change ONLY the grey handles on filling loop ,or the actual valves ,as it sounds like the filling loop may be partially open .
     
  4. As2215

    As2215

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    He removed the grey knobs and left them off for 24 hrs. He tightened filling loop with screwdriver and sled me to keep an eye on pressure. Next day pressure had gone up again so he said it’s not the filling loop!
     
  5. terryplumb

    terryplumb

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    Is this the same guy who incorrectly drew the conclusion that the EV just needed re pressurising, and then still barking up the wrong tree fitted a new EV. Then he thaught it was the HEX ,so fitted a new one !!! Not to mention the prv and the diverter valve. And now he is scratching his head . Is his company called swoppit and hope.
     
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  6. As2215

    As2215

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    Yes same guy! I am told he is a senior engineer!!! I’m with HomeServe....had 5 visits now by same guy and still not resolved. I’ve raised complaint with HomeServe but just wondered if anyone had any ideas so atleast I’m armed with some knowledge
     
  7. Repressurisizng the expansion vessel is the first port of call, but the filling loop valves do leak on these boilers, so that should have been the second check. Has he disconnected the filling loop to completly eliminate it though.

    He's obviously not that experienced on Vailent boilers though
     
  8. terryplumb

    terryplumb

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    On the off chance ,is the boiler connected to an unvented hot water cylinder by any slim chance ??
     
  9. As2215

    As2215

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    Yes he did disconnect it completely, he showed me the pipe and said something about the amount of water there should be coming out. He phoned Vaillant for advice as like you said I don’t think he knows these boilers!
     
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  11. As2215

    As2215

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    Nope definitely no cylinder
     
  12. I suspect the next change, will be ther pressure gauge itself. Are you getting charged for these visits and components, or is it all in the contract, and you're just amazed at his bafflement.
     
  13. John D v2.0

    John D v2.0

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    turn off your stop cock and open the cold tap to release the pressure. Does it still go up? If yes it's something bizarre.
    If no, next turn it on again, and turn off the DHW cold inlet on the boiler. Open a hot tap to release the pressure. Does it still go up?
    If no, it's getting in through your plate hex (but he's changed it?) or there's some other connection from the HW side to a rad...
    If yes, remove the filling loop at one end. Does it still go up?
    If no, it's your filling loop (water will be dripping out of the disconnected hose)
    If yes, must be some connection between cold water side and a rad..

    My money's on filling loop.
     
  14. As2215

    As2215

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    Thanks for your replies, luckily I am not getting charged every time he comes out or changes a part, it’s part of my contract!

    I’ve contacted him again and asked him to look at the filling loop once again, since he has already changed everything else.

    It is running at 3.0 bars at the moment, he told me I don’t need to bleed a radiator as the prv is working fine. Is that correct? I don’t want to make the problem worse!
     
  15. John D v2.0

    John D v2.0

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    Well the prv is a safety device not an operational part so it's not designed to be used for draining excess water out of the system. But presumably he will replace that for free if it doesn't seal.
    Regarding the bleeding, actually if your expansion vessel is kaput you can drain some water out of a rad and use the site in the as a kind of temporary EV.
    But I don't think you need to try that as the pressure is rising when the system is off.
     
  16. bernardgreen

    bernardgreen

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    Which should be removed after the system has been filled. Removing it will ensure that no more water can get into the heating system even if the valves are letting by when shut.
     
  17. John D v2.0

    John D v2.0

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    Should be removed and it would indeed ensure that but not strictly required for that reason.
    Should be removed for water regs because it's a temporary connection between category 1 and 3 fluid systems.
     
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