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Discuss Do unvented cylinders require a 'gravity' drain? in the Plumbing Forum area at

  1. DevsAd

    DevsAd Member

    Hi again.

    Exploring options for my bro's flat. One is to convert to a pressurised system.

    The preferred location for the new unvented cylinder would be where the current vented one is in his airing cupboard. Problem is, it would be tricky to get a gravity drain from this to the outside (he had to have his new boiler fitted in the roof hut for a similar reason to do with the condensate drain).

    I know there's pumps and stuff, but that's pants.

    Do unvented cylinders require a 'gravity' drain like this, or have I misunderstood (I'm guessing it's to do with the tundish thingy?)? If it is required, are there any solutions that don't require 'gravity'?!

    Thanks again.
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yes they do or a pumped drain
    • Like Like x 1
  3. Riley

    Riley Plumber GSR Top Contributor!!

    Are you G3 if not it might be best to let your installer assess it to ensure that flow/pressure and termination options are all up to scratch
  4. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    ^^^ as above, you need adequate pressure and flow before you can even go down the discharge pipe route . Not a DIY install , its more than “just a cylinder “
    • Like Like x 1
  5. DevsAd

    DevsAd Member

    Many thanks all.

    No, not a DIY install - I'm aware of special quals required for pressurised systems. Just trying to be as informed as possible with all the options before letting my bro loose on finding a plumber.

    Thanks Shaun. Not really keen on a pumped drain system - as would also have been the case with the boiler in the same location - so the new cylinder will require a different home.

    Cheers, much appreciated.
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