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Calling DP and Ianmcd - Vokera 80SP Excel - Losing Pressure

Discussion in 'Plumbing and Central Heating' started by WhatNext, 12 Jul 2019.

  1. WhatNext

    WhatNext

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    Hi there

    I have a question that I would like to ask you both.

    I have a Vokera 80SP Excel combi boiler. Over the course of 24 hours with the CH off and no use of the HW, the pressure drops around 0.5 Bar ( 1.2 Bar to 0.7 Bar ).

    The system has recently been topped up with 1L of corrosion inhibitor.

    The boiler was recently serviced. The expansion vessel was fine - pressured up to 1 Bar also no signs of water at the Schrader valve. There was no evidence of a leak from the AAV inside the boiler and no other evidence of any other leaks.

    The PRV has been checked - placed a clear plastic bag on the discharge pipe outside - after 24 hours the bag was empty - no water. So the EV and PRV seem fine.


    I went around all the radiators ( 5 in total ) and the towel rail.

    I used a piece of blue tissue paper and checked for leaks at the TRVs and the lockshield valves - also checked for leaks at the air vents and the blanks at the top of all the radiators. No signs of any leaks.

    I also checked for any drips on the carpet / laminate - there were none. There were no stains on the carpet or water marks on the laminate flooring.

    When the CH is on the pressure rises slightly as expected. All the radiators are hot right at the top so no indication of trapped air or gas due to corrosion. The boiler is at the top of the system so any air vents through the AAV.

    From this I deduce there must be a leak somewhere under the flooring ? I am in a first floor flat. The neighbours downstairs ( who I know well ) have not mentioned any damp patches on their ceiling ? The pipe work below the flooring is microbore.

    I am thinking about using Fernox F4 Leak Sealer, but I am concerned that it might block either of both of the heat exchangers in the boiler ?

    Would you be able to offer your opinion ?

    Cheers
     
  2. Madrab

    Madrab

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    @ianmcd + @DP
    =======
    1st check .... Using an adjustable spanner, shut off the flow and return valves at the boiler and leave for 24hrs. If the pressure still drops then it's an internal to the boiler issue, if not and it then drops when you open the valves back up, it's out on the system somewhere. That'll allow you where to focus your attention.

    IMO, never use leak sealer in a boiler where the water system water is passed through narrow heat exchanger and internal waterways.
     
  3. WhatNext

    WhatNext

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    Hi Madrab

    Thanks. I was worried about doing that test as I had read that the Vokera isolating valves have a tendency to leak once they are rotated ? Have you found that they leaked once activated in your experience ?
     
  4. DP

    DP

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    Do NOT touch those valves. Older ones will leak, newer ones will snap at the spindle after they have been in service for a while. It is distressing that a valve that is meant to isolate requires replaced once it is moved from open position.

    WRT leak, when you say boiler was serviced, what was done inside the boiler. Did the engineer go into the boiler and check seals and coupling? Did he check the heat exchanger?
     
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  5. ianmcd

    ianmcd

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    Already been sorted lads, been in touch with the OP , couldnt post the answer in the open forum, if anyone interested PM me
     
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  6. WhatNext

    WhatNext

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    Many thanks to everyone - very much appreciated :)
     
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