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Grundfos Circulator - Speed Setting

alext207 Member Posts: 4
Hey all,

Currently working to improve my home's heating system a bit (cobbler's kid has no shoes, right?) What I have is a Thermo-Dynamics S-85 boiler in a single story ranch with about 41 feet of conventional baseboard and an Amtrol Boilermate Indirect. There's a laundry list of things that still need doing (like adding an air vent to the air-scoop plugged by the installer??) but as I'm making my way around I'm realizing the current 007-F5 circulator is grossly oversized and probably contributing to pipe noise and poor system efficiency. I have a rotated flange UPS-15-58FRC circulator on the shelf, and I'm assuming I should be setting it to the "low" setting based on the small size of my system, but I was looking to make sure of this and to find if there is a good rule of thumb for choosing the speed of circulation. In turn, once things are repaired I'm assuming that slowing down the flow velocity in my system will help with the air removal issue as well.

Thanks in advance!


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    It's easier to do the math and check the chart.
    Speed 1 is probably going to be correct.
    Simply method is to put it on speed 1, check supply/return temperatures for your Delta T.
    I use 2 K-type clamp on thermistors and a DMM.

    There was an error rendering this rich post.

  • fenkel
    fenkel Member Posts: 162
    Noise and inefficiency could indicate air in system, get the air vent fixed first.. purge out any air, then reevaluate, the 007 pump might be correct...
  • Dave H_2
    Dave H_2 Member Posts: 556
    The 007 is more than enough circ, based upon the number you started with, the heating zone only needs 2.1 gpm and I am assuming that it is piped with 3/4". so the head loss is not going to be too high. About much run of pipe is there?

    And as @fenkel says, get rid of the air! Air is the bane of our existence!

    Dave H.
    Dave H