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Variable Speed Pumps

Is a seperate control required to provide feedback or is the pressure sensor integrated? And are these only really useful in multi-zone systems to cope with drops across the header when more than one zone is calling for heat?


  • Weezbo
    Weezbo Member Posts: 6,232
    it depends on the application .

    many people find them useful for injection systems.

    there are many models makes and years of a variety of circulation or injection pumps...some circs that are not available in one industry can be useful if you know of their existence and how to apply them and Where To get The PART'S'!

    i need to get after it ..its 5.30 ish an i got have to run...
  • Brad White_156
    Brad White_156 Member Posts: 11
    Most variable speed devices

    be they pumps or fans/blowers, require an external signal. Some circulators recently intruduced have integrated controls but there is only one or two manufacturers (Armstrong and Wilo I believe). Others will let me know if there are more or if I am mistaken.

    The principles are the same. The pump variable frequency drive (VFD) is one form of a device which varies the frequency (Hertz) of the incoming power from 0 to 60 Hz. in North America and 0-50 Hz. most everywhere else.

    To apply this, an external variable such as differential pressure is measured by a device known as a transducer. This sends a proportional analog (value-based) signal, usually 0-10 VDC or 4-20 mA. Each level of measurement corresponds to a certain output in those scale ranges, generated by the transducer.

    If a circulator is set up to maintain a constant differential pressure (Delta-P), the potentiometer or pot switch on the transducer is adjusted to the required setpoint. As the system pressure varies due to opening and closing valves, the transducer output changes. The pump speeds up when valves open or slows down when valves closed.

    That is but one application. Constant delta-T (temperature difference) can also be maintained, air pressure for fans too.

    Hope this helps.

  • Curious_5
    Curious_5 Member Posts: 1
    Variable Speed Pumps

    Much clearer now. Thanks Brad!
  • Ragu_5
    Ragu_5 Member Posts: 315
  • Doug Bird
    Doug Bird Member Posts: 22
    Variable Speed Pumps

    Thought I would inform the group about Taco's lineup of available Variable Speed circs. Taco has had VS circs out for about 2 years. We offer 3 types. The 0-10V, 4-20ma variable voltage input signal variety (VV) you described as well as a setpoint/adjustable delta T (VS)or Outdoor reset (VR)options. I've attached a spec sheet for your reference.
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