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ECM circulators

stonebutson Member Posts: 24
I'm trying to get my arms around the flat curve on an ecm circulator. can someone explain it to me? I see a long flat portion at 10 feet and then it drops off at a 45 degree angle for anything under 10 feet of head. My question; is that 10 ft the only place that the circ is going to works it's so called magic? Adjusting the gpm to keep delta P constant? What if your system curve is other than 10 feet (why not? Pretty common) . I get that over ten feet flow will stop. But under 10 feet we'll just be following a curve like any other circ? Do I have to adjust my system curve (throttle a ball valve) to 10 feet for the circ to be all that it can be?


  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,193
    edited October 2020
    With the Alpha I in the "Auto Adapt" mode, you can get up to 15 feet of head (4-5 gpm). The long, flat portion is at the constant pressure settings.

    Often wrong, never in doubt.
  • Jamie Hall
    Jamie Hall Member Posts: 18,738
    Keep in mind that that long flat portion is a characteristic of the pump's controller -- not the pump. You can change the head of that flat portion or -- with the auto adapt setting -- change the way the head changes with flow -- or if you set it for constant flow (if the controller has that option) it will maintain a constant flow with a vertical section of the curve between the maximum attainable head for that flow and zero head. It's all in the controller.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England