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Vokera combi boiler very rapid cycling

Discussion in 'Plumbing and Central Heating' started by Thomato, 6 Nov 2019.

  1. Thomato

    Thomato

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    I found a post on here with a similar problem and have been advised to start a new thread as this is for a different brand. This looks a very good site!

    We are having a big problem with hot water supply to taps and the shower, especially upstairs.
    Hot water will heat rapidly then go stone cold after just a few seconds before cycling to hot again, repeating ad infinitum. It makes showering very difficult and uncomfortable!

    The boiler is a Vokera Unica 32HE combi boiler that's been fitted for about five years in a very hard water area. I suspect the heat-exchanger is blocked and so not running efficiently.

    Can anybody give any thoughts or advice on this, please? I don't want to disassemble a system if it might be just a stuck valve I haven't spotted!

    Many thanks.
    Thomas
     
  2. CBW

    CBW

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    Hi Thomas,

    I suspect you are correct as it can’t disspipate the heat from the boiler quick enough, but you shouldn’t rule out other possibilities, such as the pump or diverter valve.
     
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  4. ianmcd

    ianmcd

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    With the Heating cold, run a hot tap and when the boiler fires, feel the heating flow and return and see if either heats up, if they do it is a divertor valve problem, if not yes likely your plate HX is scaled, your boiler is a decent enough boiler but really must be serviced properly every year and not just a poke and go with a flue gas analyser.
     
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  5. Thomato

    Thomato

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    I ran the tap and checked all pipes to be sure I hadn't got the wrong one and only one pipe heated up.
    By your post, I think that's the heat exchanger found out.

    Thank you!
     
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  6. DIYnot Local

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