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Vaillant Turbomax plus 824- no hot water but heating is ok

Discussion in 'Plumbing and Central Heating' started by Dd235, 6 Dec 2020.

  1. Dd235

    Dd235

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    Hi everyone, I really hope you guys can help with some advice. With bloody covid I think everyone has to was their money at the moment, worried I might have an expensive repair bill for my boiler. Would really appreciate any help.

    Ok so here's the problem,

    I have a Vaillant Turbomax plus 824 boiler. The central heating works fine however the hot water on demand isn't working correctly.

    Only 1 person lives at the property, it has tado smart heating system installed so the boiler doesn't get heavy usage.

    The boiler is not showing any fault codes to indicate what the problem is.

    When the hot tap is turned on the green light doesn't flash, as if it doesn't know there is a demand for hot water. It does show the status code s.27 though. About 3 or so minutes after I turn off the tap the boiler it briefly shows the status code s.20, s.23 and then stops at s.24, all the while the green light is still flashing. The orange light is also on indicating the main burner is ignited. The temperature changes from 32 to 62 and finally it then goes to an s.27 code. If I start the tap running at this point, I can get a short burst of hot water then just not cold but not warm water.

    With the front panel down, you can feel that the pump is vibrating slightly and after a few minutes it is very hot. Also after a few minutes the heat exchanger is also consistently hot along it so doesn't appear to be blocked. The pipes around the system feel hot too.

    In April 2019 the boiler had a refurbished pump fitted.

    Any advice would be greatly appreciated.

    After looking online it suggests it could be the aqua sensor or the diverter valve? However I can find a post that suggests the exact symptoms as my boiler. I just want to know the facts really so I can decide what to do. It's an old boiler but I don't feel like I'm in a financial situation to throw money at it or to buy a new boiler.

    Thank you in advance.

    The s codes discussed above are
    S.20 warmstart demand
    S.23 ignition sequence
    S.24 burner ignited
    S.27 pump over run
     
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  3. Gasguru

    Gasguru

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    Sounds like the turbines stuck or broken up.....0020029604
    I'd be keeping that model going as long as possible..it was the last Vaillant before the rot set in.
     
  4. Dd235

    Dd235

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    Thank you so much for replying, ok great, so it sounds like it is the aqua sensor. Thank you for the part code reference too.

    That's great to know, I've never had a Vaillant before.

    Do you think it's worth changing the diverter too? just as I've heard these go eventually too. Thank you
     
  5. Gasguru

    Gasguru

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    Original diverters were problematic and most were replaced in the first few years, they were modified and are more reliable.
    Unless there's an issue wait until the diverter plays up....eg. with warmstart on you'd notice the radiators coming on at random times as the diverter sticks or poor radiator performance.
     
  6. Harry Arcos

    Harry Arcos

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    I would also suspect the diverter valve. I believe that the aqua sensor triggers the motor in the diverter valve and when the hot tap is opened, the motor can be heard to operate. Easy enough to take it out still connected to the power and see if it moves.
     
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  8. Dd235

    Dd235

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    Amazing thank you both, this is so helpful. I'll get both parts so then I have them just in case.

    I've also read that the boiler can get full of dirt and muck over the years. Is there anything I can have done to flush out the boiler to hopefully help prolong its life?

    Thank you
     
  9. Gasguru

    Gasguru

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    There's nothing to suspect the diverter...as I said before the heating would be coming on at random times whenever warmstart kicked in.
     
  10. Dd235

    Dd235

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    Ok great, I'll start with just the aqua sensor. Would you just replace the turbine, not the full aqua sensor? Thanks!
     
  11. Dd235

    Dd235

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    Thank you so much gasguru! You have saved my Christmas! I changed the turbine and it's fixed!!!
    Thank you so much for the advice, I can't explain how much you have helped. Thank you!!! :D:D:D
     
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