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Discuss combi boiler, pressure continuously increasing. in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. Juman islam

    Juman islam Member


    I have a vaillant ecotec plus 837 and one day noticed the pressure was maxed out therefore bled the radiators to drop it down to 1.2~1.4 bar.

    Two weeks later, I noticed my pressure increased back up 2.5 bar so had to bleed the radiators again.

    A guy at work told me the increase in pressure is probably is due a failure in my filling loop. What are other peoples views on why this is happening?

    Thanks in advance.
  2. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    If it's continually increasing even when the heating isn't been used then yes you may have a faulty filling loop/link. There are other possible causes for this too though so maybe best that you get a registered engineer in to check the system over.
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  3. Rob Foster

    Rob Foster Top Contributor!!

    Turn off the filling loop at both ends and remove it carefully. If it leaks from the valve..s then call a plumber to replace the naughty valve. If the pressure still rises with the filling loop detached your problem is MUCH bigger and call a GSR combi specialist. Centralheatking
    • Agree Agree x 1
  4. JohnnyM

    JohnnyM GSR

    As above with the filling loop but could be the **deleted as mentioning internal component** Call a Gas Safe Engineer.
    Last edited by a moderator: Apr 17, 2019
  5. Coby kenny AGUILAR

    Coby kenny AGUILAR Member

    I think that model the filling loop is practically internal, built into controls (keeping it vague).

    If you have no wet work experience call an engineer
    • Agree Agree x 1
  6. Juman islam

    Juman islam Member

    Thanks lads. Got home to check the pressure and it was at 2.3 so increased again within a space of 2 weeks from 1.2.

    I've attached a picture of my where my filling loop is. Mate at work said to get the boiler serviced abit earlier than usual and get them to replace the filling loop at the same time. Is the filling loop replacement an easy DIY or best to leave to the pros? Im quite good when it comes to DIY and mechanics but never worked in boilers before.
  7. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    No pic
  8. Juman islam

    Juman islam Member

    Sorry! Pic attached now.

  9. Rob Foster

    Rob Foster Top Contributor!!

    It will not be the filling loop it might be the isolation valves, or something much more internal which requires a GSR fitter. Those
    iso valves look rather tasty and expensive to replace. So take one end of the loop off with them turned off see if water still flows before replacing. centralheatking
  10. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    Remove the hose marked in red and see if the valve is passing any water. If it is then remove the valve head marked in blue and see if you can nip the valve a little tighter with a spanner.

    • Agree Agree x 1
  11. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    How can you say it won't be the filling loop when that's the first thing any engineer would check?
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  12. Rob Foster

    Rob Foster Top Contributor!!

    the filling loop is just a connection, its the valves that might be passing chking
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  13. Juman islam

    Juman islam Member

    So after removing the hose marked in red, if there is not water leaking past the valve, does that mean the braided loop only needs changing?
  14. Rob Foster

    Rob Foster Top Contributor!!

    no the braided hose is just a connection its the integrity of the valves you are testing
    • Agree Agree x 2
  15. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    My apologies, I see what your saying, when I refer to the filling loop I mean it as the hose and valves combined.
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