Unvented cylinder system (2)

Discussion in 'Plumbing and Central Heating' started by David2749, 19 Dec 2021.

  1. David2749

    David2749

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    Hi
    My nieghbour has had a problem with his boiler over heating, an engineer has been to try and sort it out, and has concluded it's his unvented tank.
    I'm not an expert, but how many things can go wrong with this type of tank? My understand ( practical not experience) tells there are only the two valves plus the expansion tank that can go wrong, but I'm sure you will put me right on this
    Th
     
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  3. kidgreen61

    kidgreen61

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    His engineer is clearly clueless, the unvented cylinder is not a heat source, so cannot cause a boiler to overheat.
    It's possible however that the cylinder zone valve may be stuck open, causing the boiler to continue firing, a few simple tests done by a competent person will soon establish that.
     
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  4. David2749

    David2749

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    Thank you for this advice, I think the engineer should have carried out to see if this motorised valve was faulty.
     
  5. BlueLoo

    BlueLoo

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    Engineers eh....

    The stat controls the zone valve so check that is also working.
     
  6. David2749

    David2749

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    As stated I'm not an engineer, how do I check this other than taking the cover off and see if it rotates.
     
  7. DiyNutJob

    DiyNutJob

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    Over heat is often caused by insufficient flow. Increase pump speed or reduce thermostat on the boiler, or both will make a difference.
     
  8. Exedon

    Exedon

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    If you are referring to a pressured hot water cylinder you need to have a G3 certificate to work on it.
     
  9. David2749

    David2749

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    Yes, I'm aware you have to have G3, I've no intention of doing anything, but was only enquiring on behalf of my nieghbour. I just want to see him having to pay for a new tank if it wasnt needed.
    I will suggest he has 2nd opinion look at it.

    Once again thanks for you great advice.
     
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  11. Exedon

    Exedon

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    Commonly pressurised cylinders have 25 a year warranty
    But the cylinder has to be serviced yearly to keep warranty up.
     
  12. David2749

    David2749

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    I have a unvented system in my own house, other than the engineer checking the filter on the one valve and the pressure in the expansion tank, that's all he does. And this costs me £85. But guess it has to be done.
     
  13. Harry Bloomfield

    Harry Bloomfield

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    Could you/he check whether the flow pipe from boiler, is hot where it enters the cylinder and the return close to the cylinder?
     
  14. Exedon

    Exedon

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    Only way to keep warranty up.
     
  15. BlueLoo

    BlueLoo

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    Christ.

    Why?

    Get a engineer to service the system and boiler and the tank at the same time?

    I'm in the wrong job....
     
  16. BlueLoo

    BlueLoo

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    • Please do not falsify quotes
    ,
     
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