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problem with boiler

Discussion in 'Plumbing and Central Heating' started by cache, 5 Feb 2015.

  1. cache

    cache

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    hi there, ill make this as simple as possible! :)

    remaha avanta 18s boiler, commissioned in August 2010.

    lost pressure, bar went to 0. topped up, worked fine for a few days, lost pressure, etc.

    replaced pressure relief valve and expansion vessel (8 litres). we have around 12 rads and 3 towel rails.

    problem still occurring. no idea what to do apart from refill it every few days!

    edit: it has been fine from 2010 to 2014, and happened once in nov 2014 and a few times now this year.
     
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  3. andytw

    andytw

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    If you put something like a plastic bag over the end of the outlet from the PRV then you will know if that is where the water is going. If it is not going out via that route then you have a leak.

    andytw
     
  4. Cgas

    Cgas

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    Know it might sound daft but you have checked for leaks on all rad valves etc etc properly ? No marks on any ceilings ? Not sure with this boiler unless you give me gc number? but it's possible for condensers to pass pressure through the heat ex which goes straight out through the condensate pipe work which you wouldn't see it.

    Only way of testing if it's going through heat ex is by;
    Top up pressure to 1-1.5bar, isolate flow & return, leave for 24 hours, use the boiler for hot water within the 24 hours (don't turn it off altogether). After 24 hours if pressure has dropped prob is with the boiler, if no pressure drop - open iso's and if movement on gauge problem with system. It has to be heat exchanger if you've repressurised expansion & replaced prv.
     
  5. cache

    cache

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    im not really comfortable taking the boiler cover off to be perfectly honest, i just checked for leaks on valves and ceilings and couldnt find anything. someone said my expansion vessel is too small and might not be coping?
     
  6. Cgas

    Cgas

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    Your quite right you shouldn't remove the cover unless your qualified but the test I advised earlier about isolating boiler dosent require the removal of the case. Maybe worth a try if you can be without heating overnight. You'd still have hot water.
     
  7. andytw

    andytw

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    In which case you should see the pressure gauge go up to somewhere near 3 bar. That is when the PRV will open.
    Has it been OK with that expansion vessel since 2010 ?

    The pipe I suggested you check for leaking water would be outside of the building. Look for a copper pipe, may be turned back towards the wall to prevent injury from hot discharge.

    andytw
     
  8. cache

    cache

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    i must have read it before you edited that part in! im not sure we can be without heating its freeeeezing! but i will certainly ask the other half, not sure where that pipe you speak of is but ill look for it. thanks for all the help guys :)
     
  9. Cgas

    Cgas

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    Probably not the best time of the year to try this ;)
     
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  11. cache

    cache

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    i just find it so strange its been fine for years and now i move into a house, 3 weeks in and its broken!!
     
  12. Cgas

    Cgas

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    Just read over ur first post again, u sure it's a combi being 18s? Or is it on a sealed system?
     
  13. cache

    cache

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    sorry did i say combi? its not a combi, its an 18s with a megaflo hot water tank
     
  14. picasso

    picasso

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    When the boiler is cold check to see if you have water dripping from the condensate pipe, you could have a pinholed heat exchanger.
     
  15. cache

    cache

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    ill have to take the front off the boiler for that? is that the plastic tubey thing?
     
  16. picasso

    picasso

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    You dont have to touch the boiler, there should be a plastic tube under the boiler that leads to a drain.
     
  17. Cgas

    Cgas

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    No you didn't I just assumed, Ok ignore what I've said so far then, have u got pipes under concrete floor downstairs ? You won't be able to isolate flow & returns so ignore that idea. As Picasso said above, check that. But if it's dropping over a couple of days you'd have to put it into a bucket or tub to test.
     
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