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Varying mains water pressure upstairs

Discussion in 'Plumbing and Central Heating' started by PlumbBob, 1 Apr 2020.

  1. PlumbBob

    PlumbBob

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    Hi

    I have an electric shower in the en-suite that takes it cold feed from a T off from the same pipe that feeds the 2 header tanks in the attic - so it must be the mains. From that is a smaller bore copper pipe of about 2.5m length to the shower. However the flow changes from 2 to 4 l/min.
    What causes varying flow rate? Just low pressure? (But would think it would be constant)
    Shower is struggling to deal with the varying pressure and will stop heating the water.
     
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  3. terryplumb

    terryplumb

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    More likely to be a fault internal to the shower ,stabiliser valve possibly. What make / model is the shower ?
    Are you sure it's under mains pressure ?
    2 to 4 litres per minute is very low ,what is it when on fully cold ?
     
    Last edited: 1 Apr 2020
  4. PlumbBob

    PlumbBob

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    Ive took the shower unit out the equation and measured the flow going into to the shower unit
    I need to measure the pressure and compare with downstairs yes.
     
  5. terryplumb

    terryplumb

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    Do you mean you have totally removed the shower ,and the open pipe flow rate is ,2 to ,4 litres per minute ? If so what is the pressure ,static ,at the open pipe ? And what's the dynamic pressure ?
     
  6. PlumbBob

    PlumbBob

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    I removed the shower yes.
    To confirm whether variable flow was due to the shower, but it isn’t.
    I’ve not checked pressure - I’ll do that, may need some form of adapter.
    I’m thinking if pressure is low then flow is going to be weak.
     
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  8. terryplumb

    terryplumb

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    It would ,but if the flow is not constant ,then pressure has to fluctuate or there is a mechanical ,inconsistent ,intervention in the pipework. Always assuming it is mains fed and not gravity fed and ruling out airlock.
     
  9. Madrab

    Madrab

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    Are you sure it feeds the 2 cisterns in the attic? I would follow and confirm that the pipe that feeds the shower connects to the ball valves in the cisterns and isn't supplied from the body of one of the cisterns. It sounds more like the latter given the flow you are seeing.
     
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  10. PlumbBob

    PlumbBob

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    Hi, yes it has been Tee’d off the cistern’s feed pipe, probably when the house was extended. I’m not too happy about the smaller diameter so for price of it may change that out for 28mm until final 10cm
     
  11. terryplumb

    terryplumb

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    Pointless . All you need is 15mm ,what do you have ?
     
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