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  1. mutley racers

    mutley racers Plumber GSR

    of water through pipes at different pressures and sizes?
  2. mutley racers

    mutley racers Plumber GSR

    This is what I am upto. Calculating the flow to 2 showers and a bath running simultaneously.

    I installed a 25 mdpe into my house which comes off at 22. The flow rate before at my outside tap was 20 litres a minute and went down to 10 with another tap on. Now with the new pipe it overflows the weir gauge (although when testing with a bucket it was 20 litres a minute) and I get 18lpm with another tap on. With the bath on I go down to 14lpm so 3 taps.

    When checking flow rates though, it is only coming through a 15mm pipe to the tap and the maximum flow through this pipe is 22lpm at 3 bar. So, this test really is not that accurate.

    Long winded I know. I just want to see if I should put an accumulator in really.
  3. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Depends are you going to be running all 2-3 at once ?
  4. mutley racers

    mutley racers Plumber GSR

    Yep. As one shower will have 2 shower heads you can use at the same time
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    What make are you going for ?
  6. mutley racers

    mutley racers Plumber GSR

    As in shower heads? Looking at a 3 way cross water shower valve. Not sure what shower heads yet as I want recessed in ceiling but theirs are like 1k each.

    Probably looking at 18lpm each head with the bath running at same so looking at 54lpm and then the dishwasher and washing machine etc so it looks like I will be needing one.
  7. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yep also 28mm main to there from the stop tap
    • Like Like x 1
  8. EvilDrPorkChop

    EvilDrPorkChop GSR

    And I thought we were meant to be saving water :rolleyes:

    In reality are you going to be running two shower heads in the same shower at once? I have two, and I never have them both running at the same time (Although I can). Also, bigger the shower head the more you feel like you're drowning in the shower. Made the mistake of having a 300mm square soaker at first, but you felt like you were drowning when you were under it at 20lpm. So changed it for a 200mm round and it's much much better.

    Also you're saying you'll be running all these at once, but you're going to need one big cylinder of HW to supply all these at 54lpm.

    So shower at 38oc, at 18lpm will use (Stored HW at 60oc and incoming 15oc) 9.2lpm HW. * 10mins that's 90L of HW. Mutliply that by your two shower heads, that's 180l of Stored HW you require for just one shower. Add in another bath being drawn off and other things you'll be wanting 400l+ cylinder at least IMO.
    • Like Like x 1
  9. mutley racers

    mutley racers Plumber GSR

    I like to have showers with the wife you see. Saves us time when getting ready to go out and the kids like playing in the bath with the taps when we do.

    Yep, a lot of water. And, these systems will all be going in the loft!!

    Thanks for the advice guys
    • Funny Funny x 1
  10. Jerry

    Jerry GSR

    Time spent showering can vary wildly then..?
    • Funny Funny x 2
  11. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Somewhere between 20 secs to 45 secs :D
    • Funny Funny x 3
  12. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    I don't know about you but I find the expectation of showering with the wife is nothing like the reality. Rubbing soap into her back is never what I have in mind :(
  13. mutley racers

    mutley racers Plumber GSR

    Thanks for the reply.

    Maybe a thermal store would be better?
  14. EvilDrPorkChop

    EvilDrPorkChop GSR

    Personally I think no. I'm not a fan of thermal stores, an Unvented cylinder which is large enough is plenty IMO. All I was getting at was really are you going to be using 54lpm in reality. The other way to combat cylinder size if you're struggling for space too is to store the HW at a higher temperature (70oc) then put a mixing valve on the outlet mixing down to 55oc (So it works similar to a thermal store).

    I think really you'd get away without an accumulator. Your issue will be you'll always be limited to 3 bar of pressure anyway on the Unvented outlet due to the PRV so as long as you've got the flow through your incoming main and the correct pipe sizing to your showers etc. you should be fine. Are you able to do balanced cold to the house or at least showers and bath from the loft?

    OSO used to allow you to up the PRV setting if you increased the expansion and uprated the blow off on the combination valve. However I'm not sure if they still do this (Or any other manufactures) as we stopped fitting OSO.

    Final thing too, I'd avoid fitting a cylinder in a loft if possible especially in your own house. When that cylinder goes or something starts leaking it'll be a waterfall through the ceiling. Right above the bedrooms too.
  15. mutley racers

    mutley racers Plumber GSR


    Thanks for the good advice.

    I like the idea of upping the temp of the cylinder and blending down.

    Yes, easily be able to put the prv on the mains before any outlets for balanced supplies. I will also change all the piping to the correct sizes for each outlet rather than the 15mm it is all over due to a combi being in here.

    Only place for the system to go now is in the loft until I turn the garage into a utility room.

    As you have decent shower heads, can you recommend any? I am keen to try the water boarding experience and see how it goes!!!
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