Mixer shower with gravity fed cold and mains hot

Discussion in 'Plumbers' Talk' started by hamishm, Aug 26, 2019.

  1. hamishm

    hamishm New Member

    I currently have an electric shower in the bathroom with a shower pump. It's fed off the cold water tank in the roof of the building. I was wanting to replace this with a mixer shower for the sake of energy efficiency but I heard this wouldn't work well due to the unequal pressure from gravity cold and mains-fed hot.

    What's the best solution to this? I'd like to avoid a pump if possible. I also read about venturi showers - but they seem to be designed for the opposite situation - where you have gravity fed hot and mains cold.
     
  2. Joe the Plumber

    Joe the Plumber Screwfix Select

    You'll need to give us more details of your water system. Why do you have a cold tank if your hot supply is mains fed? Normally the cold would also be on the mains.
     
    WillyEckerslike likes this.
  3. hamishm

    hamishm New Member

    It's an ex-council flat in an old 1930s block. The appliances in the kitchen get their cold from the mains (and the combi boiler is in here), but the appliances in the bathroom are getting their cold from a cold tank, a pipe running down in a cupboard in the bathroom. The bathroom's on the other side of the flat from the kitchen, and only the hot water from the combi is being piped over to it.

    I'm also not sure if the flow from the mains is enough to for both the hot and cold water. It seems to be about 7/8 litres/min. All the pipes are 15mm and the main in the kitchen seems to continue up into the flat above.
     
  4. terrymac

    terrymac Screwfix Select

    If you have a cold water tank close to the bathroom ,then you also have mains cold as that's what fills the tank !! So hot and cold off the mains and a thermostatic valve is the way to go ,if the flow is good enough.
     
  5. hamishm

    hamishm New Member

    Yeah but the cold water tank is 3 floors above me and managed by the council. But I might get on to the council and see if I can get the water mains directly in the bathroom and disconnect from the tank. There's about 4 pipes in the bathroom cupboard so one of them could be mains.
     
  6. kiaora

    kiaora Guest

    Hi
    How about just adjusting the hot water temperature at the boiler when you need a shower , ?

    Then just use shower on max heat !

    It may work for you, with no cost involved .

    Good luck
    Peter
     
  7. hamishm

    hamishm New Member

    Yeah that's an idea as well. I've got in contact with the council and they are not optimistic about the other pipes in the bathroom providing mains cold. They also say the current set up is breaking bylaws as the shower pump is pumping a communal supply, so can cause problems for other users. Think the best option might be to run a mains cold pipe from the kitchen to the bathroom. Or potentially experiment with a pressure reducing valve for the hot -- but then the overall pressure might be too low for a shower.
     
  8. PT8

    PT8 New Member

    Hi hamishm

    I am in the same situation and was wondering if you found a solution and wouldn’t mind sharing?

    thanks
     

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