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Blocked condensate

Discussion in 'Plumbing and Central Heating' started by electronicsuk, 1 Mar 2011.

  1. electronicsuk

    electronicsuk

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    Hello chaps. Got called round to a friend's house today after complaining of knocking sounds coming from the boiler. I wasn't expecting to be able to do anything about it, but said I'd have a look anyway and see if it was anything simple.

    Before arriving I had assumed it would be down to circulation problems. The boiler (WB Greenstar 42CDi) had a new plate HEX fitted within the first year due to becoming blocked on the primary/heating circuit side. I mains flushed and inhibited the system last year, but it's possible that the main heat exchanger is filled with crud that the flushing didn't release.

    In any case, got there to find that the condensate neutraliser had become blocked, and the condensate wasn't able to syphon away properly. Have removed the neutraliser until Plumb Centre get a replacement through from another branch, and the boiler seems to be working just fine now. Even tried closing down all rad valves to leave circulation through the bypass only in an attempt to try and reduce circulation and see if the knocking started again, but it never came back.

    Is this pure coincidence that the problem went away and that it's likely to come back, or can a blocked condensate drain really cause boiler knocking/banging/kettling?
     
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  3. Nige F

    Nige F

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    no idea M8 - but I`m pleased you`re not going to leave the neutraliser out - and pollute the Fens ;)
     
  4. Bankrupt

    Bankrupt

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    I can assure you that a blocked condensate drain will cause exactly what you describe on this model. I have the same boiler and had exactly those symptoms when the drain froze up during the recent big freeze.
     
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  5. electronicsuk

    electronicsuk

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    Well I'm sure he'll be pleased to learn that there probably isn't another fault, as I wasn't happy to declare the all-clear when I left it. Thanks guys.

    I'd be more worried about damage the the (very old) bricks the house is constructed from around the area of the condensate drain ;)
     
  6. simond

    simond

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    This condensate stuff is virtually harmless. It is a load of hot air with a small smattering of carbonic acid.

    Add a slice of lemon, delicious :LOL:
     
  7. Bankrupt

    Bankrupt

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    Indeed - I've heard it described on this forum as being "highly acidic" . :rolleyes: It's not highly acidic (something like concentrated nitric acid is highly acidic) , it's very slightly acidic......
     
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