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Discuss How to drain only hot and cold feed to a bathroom which is on a drop from an Unvented cylinder. in the Plumbing Forum area at

  1. xpritt

    xpritt New Member

    The system has an unvented hot water cylinder which heats the water upstairs (via an immersion heater) and I need to drain down the pipes so I can move the two pipes feeding the sink in the bathroom. There are two showers (on a separate drop) one bathroom (on it's own drop) and one sink elsewhere (on it's own drop).

    Am I right in thinking I can turn off the cold water supply into the property, turn off the cylinder and just open the taps? I've done some research and it sounds straight forward but I have read about cylinders imploding so I'm a bit worried about blowing it up as I'm doing it for someone as a favour.
  2. sammathias

    sammathias Plumber GSR

    Yes isolate cold main then open hot and cold taps on the floor below you wish to work then open taps above.
  3. xpritt

    xpritt New Member

    Thank you I was just worried about the implosions I'd read about but it sounds like this is only the case if something is seriously wrong with the installation.
    • Like Like x 1
  4. dan_the_plumber

    dan_the_plumber GSR

    No you only need to worry about negative pressure (sucking back) if there is no tap above the cylinder.
    It’s like holding your finger over the end of a straw then drawing it up out of your Coca Cola. Take your thumb off (open the taps) and the vacuum is released.
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