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Pipe sizing

BigRed
BigRed Member Posts: 104
Well it off the ground I going to survey today. Should be intresting as always!!!

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Comments

  • Jeff Elston
    Jeff Elston Member Posts: 289
    Anyone, Thank you

    I was just asked to size a CW pipe for some multi-family housing, The new CW main would feed the cold and Hot for each unit. Anyone know where some charts are or any general info would be great, Thanks in advance!

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  • how many?

    How many units? You need to count the total fixture units to size the water service to the building... State plumbing book will tell ya and make sure its updated. Had plms with inspectors using old books with water wasting fixtures and then again with them rain fall, mutli ports spray heads, etc .
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Fixture units AND

    the available pressure after the meter... If you are on the low side, less than 50 psig, you may wind up increasing the size. As rjb said, look to the code in your area. It is all fixture units plus any known gpm for any exotic fixtures. Hunter's Curve will apply toward diversity (what percentage calls at a given time), both for hot and cold water.
  • jackchips_2
    jackchips_2 Member Posts: 1,338
    Be careful

    sizing any substantial water piping load. You must take into consideration the static pressure, residual pressure, the fixture that requires the highest pressure to operate, the pressure loss in the piping and the velocity, among other considerations.

    Most codes only size by fixture units and do not take into consideration the above.

    One of the best sources for information is the American Society of Plumbing Engineers (ASPE) and their data booklets.

    Best of luck,

    Jack
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Jack, you are 100% correct

    One of the drawbacks of any advice site like this is that there are always more variables than a posting can convey. All of the variables you mentioned have a critical bearing on a successful installation.

    One of the benefits of any advice site like this is that there is more than one pair of eyes...

    Thanks! Another great service you provide-

    Brad
  • Jeff Elston
    Jeff Elston Member Posts: 289


    Sounds like good info from all Thank you,

    I will need to do some research on the blds.

    I understand that the postings don't cover all the bases, I needed somewhere to start.

    I am told all the piping in the bld is the copper clad steel pipe and the time as come to replace. The plan is to install one large CW pipe and indivual water heaters at each point in the complex, doing away with the central DHW. So the new CW pipe will have to handle the total water load. Hot and Cold.

    I have replaced this pipe on heating systems befor 3/4 only. There is alot in the domestic ditrubton piping.

    Any input would be great thanks again




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  • Brad White_9
    Brad White_9 Member Posts: 2,440
    So...

    Do you have fixture counts/fixture units, static and residual pressure? We can help you if you can get that to us.
  • Constantin
    Constantin Member Posts: 3,796
    I would also ask for...

    ... a flow test to find out what the static vs. full-flow pressure is. Usually, a call to the water department plus a nominal sum of money does the trick. That way, you know what your feeding your project with, which allows the selection of a supply line and/or a booster system.
  • Jeff Elston
    Jeff Elston Member Posts: 289


    I have what I have said, I will get more info, this project is still periphery and I haven't given any time to it yet, besides these discussions witch are very helpful thank you.

    What is residual pressure?

    Would that be the pressure during a heavy draw?

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  • Brad White_87
    Brad White_87 Member Posts: 24
    Residual Pressure- You Got It!

    Well, if not the pressure, the definition anyway! :)

    Pressure during flow is the residual pressure. You may have 80 psig static pressure but under flow this could (potentially) drop significantly. My own home system has over 108 lbs. upstream of the reducing valve and when flow occurs it drops to about 95 lbs. That would be my residual pressure.
  • Weezbo
    Weezbo Member Posts: 6,232
    remember this...You can make up pressure with Volume

    buh you cant make up volume with pressure.
  • Weezbo
    Weezbo Member Posts: 6,232
    developed length

    is shortened with point of use water heaters...
  • Weezbo
    Weezbo Member Posts: 6,232
    developed length

    > I was just asked to size a CW pipe for some

    > multi-family housing, The new CW main would feed

    > the cold and Hot for each unit. Anyone know

    > where some charts are or any general info would

    > be great, Thanks in advance!

    >

    > _A

    > HREF="http://www.heatinghelp.com/getListed.cfm?id=

    > 405&Step=30"_To Learn More About This

    > Professional, Click Here to Visit Their Ad in

    > "Find A Professional"_/A_



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