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Head loss for manifolds

sriche01
sriche01 Member Posts: 29

Quick question: When calculating head loss for a radiant loop, do you add the pressure loss of each loop together, or is it just one loop that is taken into consideration?

Thanks!

Comments

  • sriche01
    sriche01 Member Posts: 29

    To be clear, I mean a manifold of multiple loops in one zone…

  • Jamie Hall
    Jamie Hall Member Posts: 24,727

    It is the pressure loss in the one loop with the greatest loss. The pressures do not add up — but the flows do.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    GGrosssriche01
  • GGross
    GGross Member Posts: 1,258

    to add to that, you will have pressure drop for the supply and return piping, valves, the manifold itself, etc. you will add the pressure drop for all of the supply and return piping system and manifold, to the head of the loop with the greatest pressure drop. That will be your total head, then add the flow requirement for every loop on that manifold, that total flow, and total head number is your pump spec, assuming you are individually pumping that manifold.

    sriche01
  • hot_rod
    hot_rod Member Posts: 23,270

    The manifold will have some flow resistance, Caleffi shows 1.23Cv for combined S&R. So very small amount

    On a high flow 3/4 snowmelt, you may want to run the pressure drop calc, and include that pressure drop of the circuit. And the glycol derate..

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    sriche01
  • sriche01
    sriche01 Member Posts: 29

    Thanks guys! I appreciate the repsonses!