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Flow and head-feet

What type of pipe/tube?

As Brad mentioned the "equivalent length" method is MUCH easier to use and very reasonably accurate at the general velocities in hydronic systems.

You can find them on the web. Try Google. Include "equivalent length" QUOTED in your search string along with the type of pipe/tube. has tables for copper tube & fittings but there's so much there that things can be a bit difficult to find.


  • Mark_46
    Mark_46 Member Posts: 312
    Taco 008

    I'm curious to know what the flow rate of the 008 is. But I dont understand the total head-feet rating?

    When I look at the GPM flow curves provided by Taco, flow increases as the 'head' decreases. I presume 'head' is pressure drop in the pipe circuit, correct? (pipe size, length and number of elbows)
  • That's right

    The longer the straw, the harder it is to blow through it.

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  • Mark_46
    Mark_46 Member Posts: 312



    Are there standard pressure drop ratings available for pipe diameter, length and 90 and 45 elbows? If I had that, i could then add up everyhting in the circuit.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Fitting Losses Depend

    on pipe size and velocity. A simple way is to assign each fitting a value equal to it's "equivalent feet of pipe" to which is added the actual straight pipe itself. The total equivalent feet or TEL is then multiplied by the pressure drop factor ("feet of head loss per 100 feet of pipe") for the given flow rate.

    If you want, e-mail me off line and I will give you a copy of a spreadsheet I developed that does just that.

  • Joe Mattiello_2
    Joe Mattiello_2 Member Posts: 94

    The Taco 008 has a relatively steep curve, and is a good candidate for systems requiring flow through long lengths of piping. Hope I didn't over simplify this, if you have specific questions I will be happy to answer them for you.
    Joe Mattiello
    Technical Support Technician
    Tel. 401-942-8000 X 484
    Fax. 401-942-2360
    1160 Cranston St
    Cranston, RI 02920
    [email protected]
  • Mark_46
    Mark_46 Member Posts: 312


    The spreadsheet would very much appreciated! I'm sorry though, I misplaced your email and I know you scramble it to avoid spamers. If you can, send me the file to my address. I believe mine displays in the forum? I have it checked in my options page. On second thought, here it is -lol.

    [email protected]
  • Mark_46
    Mark_46 Member Posts: 312
    Actual circuit measurement


    Thanks. I dont think I have specific questions on the pump itself right now. What Im looking to do for now is measure the circuits this pump is feeding so I know what the flow is to the DHW tank and the two water coils. If I know that, plus water temps in and out and CFM flow over the coils I'll be certain the system components are sized correctly. Or completely frustrated if they are not :o).
  • CC.Rob
    CC.Rob Member Posts: 128

    As a HO, I've found the following Taco resources very useful for TEL calculations, pump selection (particularly in zone valve systems), etc.

    And Brad, would you please email me your spreadsheet? Would like to compare it to mine. Address in reply. Thanks!
  • Mark_46
    Mark_46 Member Posts: 312
    Duh. I just realized email shows in the reply page

    OK, I do in fact have your email :o).
  • Mark_46
    Mark_46 Member Posts: 312
    Hey Mike

    Well the circuit to the DHW is 1" copper and the lines to the water coils are 3/4" PEX.
  • Mark_46
    Mark_46 Member Posts: 312
    Hey Mike

    The primary loop is 1 1/4" black pipe, the circuit to the indirect is 1" copper and the lines to the water coils are 3/4" PEX.

    Thanks for those other info sources. Ill check them out.

This discussion has been closed.