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friction loss

smklin
smklin Member Posts: 69
I am wondering how much friction loss i have i my heating system.



710' of 2'' pipe

2 2" 45 degree elbows

21 2" 90 degree elbows

and then i have 3 2" close return bends where the water makes a 180 degree turn

Comments

  • remodel
    remodel Member Posts: 68
    what

    kind of pipe?  Also what flows rates do you want to look at? Just a guess will help.
  • smklin
    smklin Member Posts: 69
    50 GPM

    I HAVE 50< GPM

    BLACK PIPE SCH 40
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 10,311
    Resistance

    At 50 gpm I came up with 4.66 ft of head/100 ft for 2" pipe.



    After converting the fitting footage to ft of pipe the total equivalent feet came out to 919 ft including the 710 feet of pipe.

    919 ft @ 4.66/100 ft =42.8' of head. the fitting chart I had showed 8.5 equivalent feet for a 2" screwed 90. This seems high to me.



    What do you guys show for a 2" screwed 90?
  • bob_46
    bob_46 Member Posts: 813
    Ell

    B&G lists 5 equivalent feet for a 2" screwed 90º ell .
    bob
  • smklin
    smklin Member Posts: 69
    pump

    what pump will work on that
  • Ironman
    Ironman Member Posts: 6,570
    edited February 2014
    Pump Curve

    Go on Taco's web site and use their pump sizing tool.



    I question using 2" for 50 gpm on a hydronic line. Your velocity maybe too high.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • remodel
    remodel Member Posts: 68
    pipe velocity

    At 50 gpm you are getting about 5 ft/s.  Might be too fast? If you reduce your velocity your head loss will go down too. 
  • SWEI
    SWEI Member Posts: 7,356
    How much flow do you actually need?

    Reducing flow and increasing ∆T will result pretty big wins both for first cost and electrical usage.



    50 GPM = 42.4 feet (say 20ºF ∆T)

    40 GPM = 27.9 feet at 25ºF ∆T

    30 GPM = 16.3 feet at 30ºF ∆T
  • smklin
    smklin Member Posts: 69
    < 50 GPM

    I need 50 gpm. IF I COULD GET 60 I PROBABLY WOULD TAKE IT.
  • SWEI
    SWEI Member Posts: 7,356
    Options

    in order of preference:



    Reduce the GPM requirement (where did that come from, BTW)?  Increase the ∆T, possibly with hydraulic separation and additional pump(s) downstream.



    Replace as much of the run as practical with larger diameter pipe.  Still better to isolate and branch where practical.



    Install a big pump, eat the electric costs -- and be prepared for erosion corrosion.