How to measure BAR pressure?

Discussion in 'Plumbers' Talk' started by Deke, Dec 14, 2006.

  1. Deke

    Deke Member

    Hi,

    I have just bought a bar mixer which I have tested and I get a really poor flow rate (a dribble) when on FULL hot and a good flow rate when on FULL cold. I am unsure if it is a problem with the mixer or the plumbing.

    I have mains CW and HW comes from the cylinder in the airing cupboard (same height as shower). I am unsure if the HW is pumped but there is a pump in the airing cupboard which comes on when I turn my gas boiler on to heat the water up. Is this a pumpred HW system or is the pump just circulating the HW to the boiler and back again?

    Anyway, the bar mixer is supposed to handle a 5:1 ratio imbalance. I measured the flow from CW & HW into a bucket. CW tooks 25 seconds and HW took 50 seconds to fill it. Does this suggest a 2:1 pressure ratio? How can I measure the BAR pressure?

    Thanks for any help. Sorry for all the questions.
     
  2. britishblue

    britishblue New Member

    You will never get a bar mixer to work properly with a gravity hot water supply and a mains cold water supply.

    The pump you mention is the boiler circulator pump for your heating & hot water, it has nothing to do with the pressure of your stored hot water.

    BB
     
  3. britishblue

    britishblue New Member

    The easiest solution to your problem is to exchange your bar mixer for a venturi shower mixer that uses the pressure of the cold water to suck the hot water along with it, so that you don't require a pump for a decent pressure shower. The Trevi Boost is a good example.

    BB
     
  4. Water Systems

    Water Systems New Member

    The easiest solution to your problem is to exchange
    your bar mixer for a venturi shower mixer that uses
    the pressure of the cold water to suck the hot water
    along with it, so that you don't require a pump for a
    decent pressure shower. The Trevi Boost is a good
    example.

    He have to fit 22mm all the way back to the cylinder on the hot pipe.
     
  5. TicklyT

    TicklyT New Member

    How can I measure the BAR pressure?

    One Bar of pressure will support a column of water about 10 Metres high.

    So, to estimate your hot water pressure in Bar for a gravity feed, measure the vertical distance between your cold water storage tank which feeds the hot water system and the shower outlet in Metres, and divide the measurement by 10.

    For instance, in my house the vertical distance from the bathroom shower head to the cold tank is about 1.8M, so the pressure at the shower head is about 0.18 Bar. That's why I fitted a shower pump there.

    We also have a shower room on the ground floor. Here the shower head is 5.0 Metres below the tank, so the pressure there is about 0.5 Bar. I think this gives an adequate flow there.

    Usually, water company supplies are at a pressure greater than 2 Bar, and sometimes much higher. You have to take into account pipe sizes and any other flow restrictions to estimate pressure from the flow rate.

    In theory you could measure the pressure with a transparent tube full of water, but a 20+ Metre high manometer is a bit tricky to fit in a tool box :)

    If you have mains pressure cold water, venturi showers do look like a good idea.
     
  6. Clarts

    Clarts New Member

    You will never get a bar mixer to work properly with
    a gravity hot water supply and a mains cold water
    supply.


    Yes you can, just put a PRV on the hot.
     
  7. Captain Leaky

    Captain Leaky New Member

    Reduce pressure on the hot? don't you mean the cold?
     
  8. Clarts

    Clarts New Member

    That's what I just said :)
     
  9. r2d2

    r2d2 New Member

    That's what I just said

    No it aint. You said put a prv on the hot.
     
  10. r2d2

    r2d2 New Member

    You will never get a bar mixer to work properly with a gravity hot water supply and a mains cold water supply.

    His supplies are gravity fed.
    A gravity compatible valve would be a good start.
     
  11. Clarts

    Clarts New Member

    That's what I just said

    No it aint. You said put a prv on the hot.


    I was taking the pi5s fvckwit
     
  12. r2d2

    r2d2 New Member

    I was taking the pi5s fvckwit

    Well the person asking for the advice may not realise that you insulting moron.
     
  13. Clarts

    Clarts New Member

    My pi55 take was meant for captain leaky as I got my hot n colds crossed but I bet thats nothing new for a chancer like you. Go away A5S wipe....
     
  14. r2d2

    r2d2 New Member

    Apoligies BB. Have just re -read the OP,s post.
     
  15. r2d2

    r2d2 New Member

    I got my hot n colds crossed but I bet thats nothing new for a chancer like you.

    No nothing new, we can all make mistakes.

    Go away A5S wipe....

    No comment. :(
     
  16. Captain Leaky

    Captain Leaky New Member

    c'mon girls put the stilletos down ;)
     
  17. Clarts

    Clarts New Member

    Yeah what the hey, tis the season to be jolly n stuff. Merry Christmas R2d2
     
  18. Captain Leaky

    Captain Leaky New Member

    Aah an apology ! wonder if DP knows what they are??
     
  19. r2d2

    r2d2 New Member

    And Merry Christmas to you Clarts.

    We had a poster on here a while back who fitted an equalising valve to solve a problem similar to the OP,s.
    Indeed if memory serves me correctly Doitall fitted the valve. :)
     
  20. r2d2

    r2d2 New Member

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