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    gpm (5 Posts)

  • Paul S Paul S @ 7:05 PM
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    gpm

    Hey everyone.... This question is regarding a snow melt system with a mixture of 30% glycol....from the manifold through the 5/8" pex loops (6 of them) the GPM for all 6 of them is 6.84 GPM(1.14GPM per loop)....The head loss for the MANIFOLD is 4.5 ft HD....my question is how do I figure the size of the pipe from boiler to manifold (snow melt load=81,225 btuh/h) do I use 1"?....and how do I find the head loss from boiler to manifold, and do I add it to the 4.5 ft hd from the loops?....need this to size pump...thanks Paul S
  • Gordy Gordy @ 7:31 PM
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    Supply return piping

    Should be sized to carry the BTUs, and flow rate required for the load. Yes the supply/return piping is additive to the manifolds head loss.

    You might squeak it out of 1" with a bigger circ, which brings higher head losses, or go to an 1 1/4, and get buy with a smaller circ.
  • Paul S Paul S @ 8:12 PM
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    gordy

    Thanks for response....so if I use 1" 1/4"pipe because using 1" would be at it's max with 82000 BTUs.....how would I find the head loss of the 1" 1/4"pipe it's about twenty feet both ways and about 6 elbows?...thanks Paul S
  • Gordy Gordy @ 8:48 PM
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    Calculations

    http://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf

    http://mobile.engineeringtoolbox.com/

    To invaluable links.

    In the copper .org hand book you will find head loss for various pipe sizes fittings , and types of copper pipe. Enjoy
  • Rich Rich @ 10:44 PM
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    Can you say

    Snow melt using a Bumble Bee Circ . 42 watts to melt snow ? If you can keep the head pressure in the S&R section below 4 ft you can use the Bumble Bee for this system and keep the Delta T wherever you want it .
    You didn't get what you didn't pay for and it will never be what you thought it would
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