1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Boiler dropping pressure when heating turned off

Discussion in 'Plumbing and Central Heating' started by Ajcreece, 3 Nov 2020.

  1. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Hi just after some advice or if there is anything I can do before calling an engineer out.

    We have been in our home 2 years and the boiler is about 10 years old baxi duo tec 33 boiler I believe and never had an issue. We are having a problem now where as when the heating is on its perfectly fine and will stay on without fault until I turn it off but after being turned off about 30 mins or so after being turned off the pressure completely drops and needs topping back up. If the heating isn't on the boiler holds pressure as it will do when the heating is on but like I said completely drops after being turned off. Is there anything that I could try myself?

    Many thanks
     
  2. Sponsored Links
  3. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    5,239
    Thanks Received:
    1,067
    Country:
    United Kingdom
    Expansion vessel problem , possibly.
    When heating is on ,does pressure increase to around 3 bar ?
     
  4. Chris_W

    Chris_W

    Joined:
    26 Sep 2019
    Messages:
    4,832
    Thanks Received:
    1,322
    Location:
    North
    Country:
    United Kingdom
    Check the safety discharge pipe, usually ran outside in copper. If it’s dripping the. Likely an expansion vessel issue or prv issue.
     
  5. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Thanks for both replies

    As its under the stairs I have never looked if the pressure goes up i just top it up and turn heating on and come away.

    I have checked that pipe and nothing comes out of it.

    I have spoke to a work colleague who is a plumber and he has mentioned either a leak or expansion vessel problem. but I've never been able to get him round to diagnose!
     
  6. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    5,239
    Thanks Received:
    1,067
    Country:
    United Kingdom
    Put the heating on and take a look at the gauge.
     
  7. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Yeah I will do and ill let you know will be tomorrow tho now. If I remember correctly I've watched once and it didn't go up but not 100 percent sure of top of my head. Need to get it sorted tho Mrs is pecking my head lol
     
  8. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    5,239
    Thanks Received:
    1,067
    Country:
    United Kingdom
    Ha ha ,join the club mate !
    Leave c/ heating on for an hour then check pressure.
     
    • Thanks Thanks x 1
  9. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Cheers pal will report back to you tomorrow
     
    • Like Like x 1
  10. Sponsored Links
  11. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Hiya pal

    Put heating on and pressure seemed to stay pretty solid to where I topped it up to
     
  12. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    5,239
    Thanks Received:
    1,067
    Country:
    United Kingdom
    Well if the pressure doesn't rise significantly when central heating is running then the expansion vessel would appear to be working.
    Does the pressure drop to zero 30 mins after turning heating off ?
    And does it happen every day the heating is used ?
     
    • Thanks Thanks x 1
  13. jeff the gasman

    jeff the gasman

    Joined:
    8 Dec 2007
    Messages:
    12,360
    Thanks Received:
    4,314
    Location:
    Cheshire
    Country:
    United Kingdom
    It’s the PRV more than likely.
    Easy fix and get a competent person out.
    Expansion vessel recharge and a bit of a clean.
     
    • Thanks Thanks x 1
    • Like Like x 1
  14. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    5,239
    Thanks Received:
    1,067
    Country:
    United Kingdom
    Quote " I have checked that pipe and nothing comes out of it."

    Check it by tying a bag over it.
     
  15. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Yes about 30 mins after turning the heating off and it drops every time.

    Gonna go tie a bag to it now and check in morning
     
    • Like Like x 1
  16. jeff the gasman

    jeff the gasman

    Joined:
    8 Dec 2007
    Messages:
    12,360
    Thanks Received:
    4,314
    Location:
    Cheshire
    Country:
    United Kingdom
    A system with a flat vessel and no air in radiators will lose a tablespoon of water and fault.
    A system with a full vessel and a bit of air in the radiators would take a long time.
     
  17. Ajcreece

    Ajcreece

    Joined:
    3 Nov 2020
    Messages:
    9
    Thanks Received:
    1
    Country:
    United Kingdom
    Just gone out to the bag this morning and it was damp with a tiny little bit of water in the bottom
     
Loading...

Share This Page