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

Pressure problems on a Gloworm 30cxi boiler

Discussion in 'Plumbing and Central Heating' started by vegasgo, 8 Dec 2011.

  1. vegasgo

    vegasgo

    Joined:
    6 Jul 2004
    Messages:
    111
    Thanks Received:
    1
    Country:
    United Kingdom
    We had a Gloworm 30Cxi condensing combination boiler installed 6 years ago, with new rads and 50% new pipe work.

    Ever since its always had a pressure issue, but topping it up once in a while it all that has been needed, apart from a couple of small pressure-related repair jobs.

    Now, it has all gone belly up. The pressure was lost again and we couldn’t get it back. Engineer has fitted new expansion vessel and divertor vale, cleaned some other bits, but it still doesn’t work for long. The pressure drops to zero within the hour. Fill it back up, and it jumps from 0 to 0.9 immediately, goes up more, than goes down again.

    Engineer said the heat exchange is dirty and the system needs a power flush with sealant. It could be air-blocks somewhere, but probably a leak – nothing is apparent though, rads all checked, no damp issues. The only place where it could be is the under the living room floor, where there is lots of pipework.

    So, is it was worth ripping up the floorboards to check for leaks, or go ahead with the power flush and sealant? Have heard power flushes are a bit of a gimmick and don’t want to spend even more money on something that may not work. Any advice gratefully received, thanks.
     
  2. Sponsored Links
  3. bobw1956

    bobw1956

    Joined:
    19 Apr 2005
    Messages:
    454
    Thanks Received:
    38
    Location:
    Gwent
    Country:
    United Kingdom
    Pressurise the boiler to 1.5 bar turn the boiler off, over night,isolate the boiler feed&return,check pressure in the morning to determine the pressure loss is the boiler or the pipework ;)
     
  4. Whitespirit66

    Whitespirit66

    Joined:
    15 Dec 2007
    Messages:
    8,012
    Thanks Received:
    755
    Location:
    Bristol
    Country:
    United Kingdom
    It's normal for sealed systems to need topping up occasionally. However, the losses you are now getting should be evident.

    I think your engineer is clutching at straws, and could have you spending money for no result. As said above, do some detective work, and isolate the boiler on the flow and return valves underneath.

    If it's the boiler, could be pressure relief valve. Does anything come out of PRV pipe that goes through wall to outside? Is the new exp. vessel correctly pressurised? See FAQs. Could be pinhole in DHW plate heat exchanger.

    If your engineer is struggling, and it is the boiler, I would try someone else. Or, if not, get Glow Worm to do a fixed price repair.
     
  5. vegasgo

    vegasgo

    Joined:
    6 Jul 2004
    Messages:
    111
    Thanks Received:
    1
    Country:
    United Kingdom
    Thanks guys. I will try the first suggestion and see where we go. When I turn the boiler back on in the morning, do I open the feed and return first?
     
  6. vegasgo

    vegasgo

    Joined:
    6 Jul 2004
    Messages:
    111
    Thanks Received:
    1
    Country:
    United Kingdom
    Just to add, the engineer did do a pressure test, he isolated the boiler from the rads and pumped them up to 3bar pressure – it dropped 1 bar in minutes.
     
  7. Whitespirit66

    Whitespirit66

    Joined:
    15 Dec 2007
    Messages:
    8,012
    Thanks Received:
    755
    Location:
    Bristol
    Country:
    United Kingdom
    Therein lie your problem. Down to detective work to find leak.

    The living room floor sounds favourite. Could poss leak under here, and you wouldn't know,
     
  8. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
  9. Sponsored Links
Loading...

Share This Page