Cold water tank overflowing with hot water

Discussion in 'Plumbers' Talk' started by Tiago, Oct 8, 2019.

  1. Mike83

    Mike83 Screwfix Select

    Replacing the water tank would be a simple job and the pipework could be made a bit neater at the same time.

    The coil side of the cylinder could be capped off and tested. Or fill the heating system to 1.5 bar and remove the filling loop
     
    terrymac likes this.
  2. Tiago

    Tiago Member

    how can it be tested?
    why didn't he! AAAA
     
  3. Mike83

    Mike83 Screwfix Select

    If getting a combi then gas pressure is easily overcome by upgrading the gas pipe between the meter and boiler.
     
  4. Tiago

    Tiago Member

    So this is a flat, I'm in the 4th floor, not sure if I would be allowed to do that.
     
  5. Mike83

    Mike83 Screwfix Select

    Cap of the flow and return pipes before they enter the cylinder then refill the boiler.
    If the problem persists then it’s not the coil.
    If the problem goes then it’s the coil.

    But it’s easier to just fill the pressure to 1.5 bar. Then remove the filling loop.
    If the problem persists and the pressure remains at 1.5 then then it’s not the coil.
     
    terrymac likes this.
  6. Mike83

    Mike83 Screwfix Select

    It would only be a problem if the gas meter is remote from the flat.
     
  7. terrymac

    terrymac Screwfix Select

    Did engineer top up your system pressure and remove the filling loop ?
     
  8. Tiago

    Tiago Member

    I’m getting another engineer coming on Monday to get a look. I’m going to beg him to try doing this.
    If he fill the pressure, remove the loop, and it stops. Then it’s the coil? Could it be left like that? This means I would have to replace the hot tank?

    If it still happens, is there any other hope on what it could be?

    Also, would it make any sense (is there any chance) just filling the pressure - without removing the loop - would fix the issue?
     
  9. Tiago

    Tiago Member

    He didn’t.
    I’ve asked him if he could, he said it would make no sense because the pressure would be lost in the coil - I think this is what he meant
     
  10. Mike83

    Mike83 Screwfix Select

    Hilarious.
    If he actually carried out the test and the pressure was lost through the coil then that would mean the fault had been identified.
    But instead he done nothing.

    The pressure can only be lost through the coil if the filling loop is passing.
     
  11. terrymac

    terrymac Screwfix Select

    Don't you think that the pressure would drop even if the filling loop was removed , as the system isn't sealed Mike ? But of course the loft tank couldn't continue filling.
    Tiago ,what area are you in ?
     
    Mike83 likes this.
  12. Mike83

    Mike83 Screwfix Select

    It would drop if the filling loop was disconnected but then the fault would disappear.
    That’s what I meant Terry.
     
    terrymac likes this.
  13. Mike83

    Mike83 Screwfix Select

    This fault can only be caused by the coil if the filling loop is passing. If the filling loop wasn’t passing and the pressure was lost to the coil then the fault would disappear.
    If the filling loop was passing you would expect the gauge to be higher and prv maybe lifting.
     
  14. terrymac

    terrymac Screwfix Select

    Bear in mind if its passing ,its not at full flow ,the system isn't sealed ,its a flat on the 4th floor ,and I wonder what mains pressure the op is getting ,on a possibly shared main. Its not beyond the bounds of possibility for the gauge to register zero. With no chance of the PRV lifting.

    It would take two minutes to undo the filling loop and see if it fully closes.
     
    Mike83 likes this.
  15. terrymac

    terrymac Screwfix Select

    Its a sad situation that there have been 3 ,or is it 4 ,pro's that have attended the op' s property without conclusively diagnosing the fault.
     
    Mike83 likes this.
  16. Mike83

    Mike83 Screwfix Select

    I had thought of this yesterday but dismissed it for a reason i can’t remember.
    This is just a process of elimination until the fault is found.
     
  17. Mike83

    Mike83 Screwfix Select

    It can be difficult diagnosing based on photos and words.
    Being onsite you can see the full picture.
    None have even tried anything yet.
    The process of elimination needs to start.
    Eliminate taps.
    Eliminate boiler/coil.
    Even cap off certain pipes at tee pieces if required.
     
    terrymac likes this.
  18. Tiago

    Tiago Member

    I'm in Hoxton/London. Are you any near? haha
     
  19. terrymac

    terrymac Screwfix Select

    Lancashire unfortunately.
     
  20. Tiago

    Tiago Member

    Well, my engineer appointment for today was canceled, I might have news on Wednesday when it was rescheduled for.
    I'm going to see if they can replace the hot water tank, the guy from British Gas that came to quote a boiler today said that it's very likely to be the coil too.
    He did quote another system boiler for me too - apparently, that's what I've right now.
    He said that I can't have a combi boiler (again), because the meter is on the ground floor, and I'm on the 4th, and the pipe is 22mm, he thinks the pressure will never work. I've asked some other companies for quotes too, but none came back to me yet.
     

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