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Changing from vented to Unvented hot water cylinder

Discussion in 'Plumbing and Central Heating' started by kofi2003uk, 3 Oct 2020.

  1. kofi2003uk

    kofi2003uk

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    hi everyone
    am planning on changing my old 20 year old vented hot water cylinder to an unvented system. i currently have shower pumps as without shower pumps, there isnt enough pressure when showering.

    however am happy to put in an unvented cylinder ,which means i can get rid of the pumps which are noisy anyway.

    my house though was built in 1999 and has plastic piping/push fit on central heating and bath room sinks. i have not had any issues so far but am worried whether the plastic/push to fits can withstand mains water pressure when i change to unvented. should i be worried? i live in essex by the way, if that helps in giving advise ref to water pressure on mains.
    can changing over to unvented lead to water leaks from these push to fits plastic pipes which was put in in 1999 when property was built.

    also i spoke to a plumber and he said he will recommend uvgold2 indirect unvented 180L? are these any good or should i avoid them please?

    anything i need to be aware of before changing over to the unvented please?

    by the way, i plan to keep the boiler expansion tank in the loft. no change there unless it will be really silly to leave it as such?

    so in summary replace vented hot water system with unvented-remove the cold water tank from loft. leave the boiler expansion tank alone in loft as it currently is. works fine so my plan is to leave it alone.

    many thanks
     
    Last edited: 3 Oct 2020
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  3. terryplumb

    terryplumb

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    Check what your mains pressure is .
    Yes ,plumbing fittings not previously subjected to mains pressure can leak when changing over.
     
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  4. Sard

    Sard

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    Based on my very limited understanding, the pressure from the hot water feed should be reduced to match the pressure from the cold main. Obviously this is only a possibility if you have good mains pressure to begin with.

    But I could be taking out my backside :censored:
     
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  5. ianmcd

    ianmcd

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    What you are referring to is a balanced cold feed, the control group on the unvented has a take off point for this , you really need to get your supply pressure and flow rate checked before even considering an unvented, they are great if you have an adequate supply
     
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  7. kofi2003uk

    kofi2003uk

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    sounds like changing over to mains pressure with my house build with plastic push to fits could end up in disaster? hmm thing is i have no idea how many push to fit connections may be under the floor and nicely covered until i start seeing leaks!
    maybe am stuck with the vented system and my noisy pumps.
     
  8. fezster

    fezster

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    Push fit installed properly is no more prone to leaks than badly soldered copper. Most new builds are done in plastic now and they're absolutely fine.
     
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  9. SandyLyon

    SandyLyon

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    If the house was plumbed with pushfit when built it should have been pressure tested at first fix.
    Depending on the make of pushfit there are different test requirements, if ‘O’ ring first (polyplumb, old style Hep20) there should have been a low pressure and high pressure test up to 18 bar, grab ring first style (Hep2o, poly fit etc) the test is 1.5 times the working pressure.
    So if installed correctly and tested as per manufacturer’s instructions you should be ok.
     
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  10. kofi2003uk

    kofi2003uk

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    thank you both. the house l live in was built in 1999 so the push fits are appx 21years old. i guess push fits and plastic pipes were new then hence my concern but i may be wrong.
    am more worried about the number of push fits hidden under the floors. i would like to think the builder at the time wouldnt have any joints/push fits under floors in case of leaks but who knows.
    maybe am worrying unnecessarily. lol i hope. i would really like to change over to unvented if potential leaks from plastic push fits wasnt an issue.
     
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