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Worth having communication pipe upgraded?

Discussion in 'Plumbing and Central Heating' started by Hessles, 5 Mar 2014.

  1. Hessles

    Hessles

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    Hi all,

    Any advice would be greatly appreciated!

    Bit of background: House has an unknown size feed pipe but at the house stopcock end it is 20mm MDPE as a water meter has been fitted. The water main is 100mm Ductile Iron which runs in the footpath outside the house. There is a boundary box with a stop tap in which I estimate is 1m from the main (footpath is 2m wide)

    I'm going to overlay the service pipe in 32mm MDPE as I'd like to install an unvented cylinder and wondered if the (1m) communication pipe would pose much of a flow restriction and be worth paying to be changed?

    [​IMG]

    House no. 27

    Craig
     
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  3. Agile

    Agile

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    Without knowing what size it is its impossible to say.

    An unvented cylinder really needs a MINIMUM of a dynamic flow of 22 litres per minute @ 1.0 bar

    Measure what you have at the moment and then remeasure when you have upgraded to the 32 mm pipe. Only then can you judge if its necessary to upgrade the communication pipe.

    That can be quite expensive too. Often about £500 or more!

    Tony
     
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  4. Hessles

    Hessles

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    How is the dynamic flow calculated?

    I have a pressure guage available if that will help at all?
     
  5. Agile

    Agile

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    Its not calculated, its measured!

    Put your pressure gauge on a cold outlet, garden tap or washing machine perhaps.

    Take cold water from taps until the pressure reduces to 1.0 bar and the measure each flow rate individually with ALL of them running and add them together.

    Tony
     
  6. Hessles

    Hessles

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    Thanks very much for that! Much appreciated
     
  7. Hessles

    Hessles

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    Would it be beneficial doing it at a particular time of day?
     
  8. Agile

    Agile

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    The worst case is usually when people have finished work and bathing and cooking and often 5.30 to 7.30 in the evening.

    That does vary a little according to the social class of the neighbourhood and typical working hours for the kind of jobs they do.
     
  9. Tipper

    Tipper

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    Or in my case whether the farmer at the end of the lane is washing his cows' udders! :LOL: Pressure varies from 4 to 6 bar.
     
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  11. Agile

    Agile

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    In your case you can fit a 3 bar reducing valve and still have more pressure than 90% of London!
     
  12. Hessles

    Hessles

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    Tony,

    I've measured the existing flow using the above method. I got 32 litres per minute out of 2 taps at 1.5 bar. I couldn't get it down to 1 bar without using the garden tap, I'll do this tomorrow when I get a hose union to direct the flow down the drain via some hose.

    Is this sufficient for an unvented cylinder?

    Mains feed is in the garage which is going to be knocked down and rebuilt as we're extending above it so upgrading and moving it won't be hard work.

    New feed, boiler and cylinder can all go in the new utility to maximise flow for 2 bathrooms.
     
  13. Agile

    Agile

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    That is more than enough!

    But measure it again at 1.0 bar as thats a better benchmark pressure for reference purposes.

    Tony
     
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  14. Hessles

    Hessles

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    Thanks for your help Tony, in your experience would I gain anything from overlaying the main feed without doing the communication pipe? (It wouldn't be much effort) The run would be about 15 metres
     
  15. Agile

    Agile

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    Based solely on your figures I would say that you don't really need to do anything at all.

    But if its easy for you then upgrade to 32mm as that will do no harm and gives the best possible results.

    Tony
     
  16. Hessles

    Hessles

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    Thanks for all your help before!

    We're finally at the stage of overlaying the main feed in 32mm MDPE.

    I've contacted Secern Trent about upgrading the meter size and there's 2 options 22mm and 30mm which threw me!

    Does a 30mm meter take 28mm pipe? I've got to get the pipe work ready for the upgrade prior to their visit.

    Craig
     
  17. Agile

    Agile

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    You will need to ask them.

    But its likely to be a blue poly size so probably for 32mm.

    But beware of the charges.

    In many cases they charge an extra standing charge for larger pipe sizes.

    Tony
     
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