Worcester 38cdi boiler - no pressure

Discussion in 'Plumbers' Talk' started by m8thu, Sep 25, 2021.

  1. m8thu

    m8thu New Member

    Hi

    Before I start cutting holes randomly to find a leak I thought I would just ask for some advice.

    We have a Worcester 38cdi boiler in our holiday cottage, though the cottage is sadly occupied by the mother in law who decamped to there during COVID and now won’t leave! Sigh! The boiler has been working fine, however 3 days ago it stopped working as there was no pressure all of a sudden. I tried to fill and bleed the system, but the best I could get it to is 0.5 bar and the second I stopped the water flow in the needle dropped to zero immediately. I’ve checked all the rads, I’ve checked so see it water is coming out of the pipes outside, I’ve trying filling the system for an hour to expose the leak, but no signs of water, I’ve even chopped a hole in the ground floor ceiling where there was a water mark, however that was from when she flooded the place by leaving the hot water tap on in the bathroom for 4 hours (I could swing for her). So does anyone have any other ideas what I can try or look for before I start chopping walls and ceiling out?

    To be honest, there is no love lost between the mother in law and I and for all I care no heating may freeze her out of the place (hopefully!), however the wife feels guilty and is now pushing the idea of moving her in our house so all help would be much appreciated!!

    Thanks
     
  2. Mike83

    Mike83 Screwfix Select

    Top up the pressure and close the isolation valves on the boiler.
    This will identify if it’s a leak on the system or boiler.
    If the pressure holds then drops when the valves are opened it’s on the system.
    If the pressure continues to drop with the valves closed it points towards the boiler.
     
  3. m8thu

    m8thu New Member

    Thanks.

    Where would the water leak from in the boiler as I can’t see any water leak from the boiler!

    Thanks again.
     
  4. terrymac

    terrymac Screwfix Select

    Check the condensate pipework to see if water is running out as the system is filling.
     
  5. m8thu

    m8thu New Member

    Hi

    Checked it when system was filling up for an hour and not a drop out of the condensate pipe outside.

    Thanks
     
  6. Mike83

    Mike83 Screwfix Select

    Could be leaking from the prv or condensate pipework. If so it wouldn’t be evident from looking inside the boiler.
     
  7. m8thu

    m8thu New Member

    Hi

    Checked prv and condensate pipe work outside when filling the boiler for an hour and not a drop out of either.

    Sadly I’m feeling the plasterboard saw may be next step!!

    Thanks
     
  8. terrymac

    terrymac Screwfix Select

    If no water is coming from PRV or condensate then you have a leak on the system .
    Are you sure the pipes you are looking at outside are definitely the above quoted ?? Show us some pics.
     
  9. terrymac

    terrymac Screwfix Select

    If you filled the boiler ,open filling loop, for an hour ,there will be a lot of water
    and if you can't see any signs of it ,there must be a leak below floor level.
    Any pipework buried in concrete floor ?
     
  10. m8thu

    m8thu New Member

    I would have thought so too, but nothing. The floor is concrete and no pipe work buried in the floor and I know as I did the renovation work. Am just baffled, been doing properties up for years and come across most things, but this has just baffled me.

    Thanks
     
  11. terrymac

    terrymac Screwfix Select

    Is water actually going into the boiler ? Can you hear it ?
     
  12. m8thu

    m8thu New Member

    Yes, definitely going in as you can hear it and the pressure does rise from zero to 0.5 bar when filling but then it won’t go any higher and drops to zero as soon as I turn inlet valve off.

    Thanks
     
  13. terrymac

    terrymac Screwfix Select

    When bleeding all radiators ,do you get water from ALL of them ?
     
  14. m8thu

    m8thu New Member

    Yes.

    I filled and bled them yesterday and all filled and water came out. When I stopped filling, I rechecked them, as pressure was back to zero, and they were sucking in air when opened.

    Thanks
     
  15. terrymac

    terrymac Screwfix Select

    Very odd that there are no visible signs , good luck trying to find the leak ,do keep us informed.
     
  16. m8thu

    m8thu New Member

    Will do.

    I’m loathe to start cutting out plasterboard without any visible signs of water, but it looks like I’m going to have to find this problem.

    Thanks for all your advice and will keep you posted.
     
  17. kiaora

    kiaora Screwfix Select

    hi
    sounds like you have an open end somewhere ?
    did you install the system ?

    bit of a long shot, but...
    if not, some installers, when installing pipes on the ground floor,
    fit a drain valve outside, to make draining the system easy ,
    if this fails, or is maliciously been tampered with and left open ?
    it could be anywhere on the outside wall below the floor level.
    good luck
    peter
     
  18. m8thu

    m8thu New Member

    Hi Peter,

    Normally I do the plumbing, but I called a plumber in for that bit of the project as I was flat out, so I can’t remember where the pipes run. I don’t remember seeing the drain valve outside, but I will have another check tomorrow, am sure it was in the lounge area inside. Good thinking though!

    Problem is with the amount of water running into the system for an hour I should have found water internally if I’ve got an open end and can’t find a drop, despite chopping out some ceiling and punching holes in the ground floor ceiling beneath each upstairs rad.

    I’m just totally baffled!!

    Thanks
     
  19. kiaora

    kiaora Screwfix Select

    hi
    with the filling loop open, the old 'ear to metal rod,' as the water inspectors use, trick, may help track the noise volume ?

    also. if you can recall where the pipes are, cutting in a couple of valves, will isolate a section, ?

    ideally isolate upstairs, downstairs to start. then the system will half work ?

    process of elimination,
    good luck
     

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