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Discuss Unbalanced cold feed to shower in the Bathrooms, Showers and Wetrooms area at

  1. DIYBS4

    DIYBS4 New Member


    I have a mixer shower which is fed from a gravity hot water cylinder and mains cold water (not my doing, its already in the house we bought).

    When I turn the shower on, nothing comes out of the head until I turn the basin hot tap on and off again and then the shower starts. Once it's running it works fine.

    I have replaced the shower cartridge which has made no difference.

    I figure the issue is with the unbalanced pressures of hot and cold to the shower.

    I think I probably need a Pressure Reducing Valve on the cold feed to the shower to match the static pressure to the hot side. The header tank is about 5m above shower head = 0.5 bar. But I can only find PRVs which go down to 1 bar.

    Someone has suggested a flow restrictor on the cold feed, but i don't think that wouldn't affect static pressure, only dynamic.

    Any suggestions?

    Thank you
  2. waddycall

    waddycall New Member

  3. daWilko

    daWilko Member

    Hi - what happens if you turn off the cold supply to the shower? I've had issues where the shower wouldn't get hot due to cold being higher pressure, but not seen no flow at all. Has it been like this since you moved in?
  4. SimonG

    SimonG Trusted Plumber Top Contributor!!

    Why haven't you followed stevetheplumbers advice he gave you on the other thread?
  5. DIYBS4

    DIYBS4 New Member

    I think Steve the plumber is right but i can only find a PRV to go down to 1 question now is do I need it to go down to 0.5 bar to match the hot?

    Thank you
  6. DIYBS4

    DIYBS4 New Member

    Yes it has been the same since we moved in.

    I will try turning off the main stop tap (there’s no local isolation to the shower) and see if that changes things.

  7. DIYBS4

    DIYBS4 New Member

    Looks like it might do the trick, but i will have to reconfigure the plumbing to fit it in. Was hoping to just cut a PRV in to the existing pipe. Thanks anyway though, maybe this is the only option.

    Anyone used these before?
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