Changing from vented to Unvented hot water cylinder

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

  1. kofi2003uk

    kofi2003uk

    Joined:
    5 Jan 2007
    Messages:
    441
    Thanks Received:
    5
    Location:
    London
    Country:
    United Kingdom
    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
  2. Sponsored Links
  3. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    6,345
    Thanks Received:
    1,334
    Country:
    United Kingdom
    Check what your mains pressure is .
    Yes ,plumbing fittings not previously subjected to mains pressure can leak when changing over.
     
    • Thanks Thanks x 1
  4. Sard

    Sard

    Joined:
    20 Feb 2020
    Messages:
    194
    Thanks Received:
    4
    Country:
    United Kingdom
    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:
     
    • Thanks Thanks x 1
  5. ianmcd

    ianmcd

    Joined:
    15 Aug 2010
    Messages:
    23,986
    Thanks Received:
    10,090
    Location:
    Livingston
    Country:
    United Kingdom
    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
     
    • Thanks Thanks x 1
  6. kofi2003uk

    kofi2003uk

    Joined:
    5 Jan 2007
    Messages:
    441
    Thanks Received:
    5
    Location:
    London
    Country:
    United Kingdom
    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.
     
  7. Sponsored Links
  8. fezster

    fezster

    Joined:
    30 Jan 2013
    Messages:
    561
    Thanks Received:
    65
    Location:
    London
    Country:
    United Kingdom
    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.
     
    • Thanks Thanks x 1
  9. SandyLyon

    SandyLyon

    Joined:
    21 Oct 2012
    Messages:
    626
    Thanks Received:
    140
    Location:
    Lancashire
    Country:
    United Kingdom
    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.
     
    • Thanks Thanks x 1
  10. kofi2003uk

    kofi2003uk

    Joined:
    5 Jan 2007
    Messages:
    441
    Thanks Received:
    5
    Location:
    London
    Country:
    United Kingdom
    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.
     
  11. kofi2003uk

    kofi2003uk

    Joined:
    5 Jan 2007
    Messages:
    441
    Thanks Received:
    5
    Location:
    London
    Country:
    United Kingdom
    quick update... the system has been changed over to unvented a month ago and so far no problems. one pipe/connector in main bathroom under sink gave up when mains was turned on but plumber spotted quickly and was fixed so flood was minimal. no other issues so far so am really happy. i got rid of the bloody noisy shower pumps too (y) lol one main reason i wanted to get rid of the open vented. whew! thanks all and a HNY and good health to all.
     
    • Like Like x 4
  12. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page