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Circulator test

bluemoon Member Posts: 40
Any of our hydronic experts have a method of determining a bound or burnt out circulator by using a multimeter or amprobe?


  • Tinman
    Tinman Member Posts: 2,808
    Here's a start -
    As with troubleshooting most loads, i.e. pumps or motors, check for the rated voltage at the load. If there's voltage, there should be amperage. Unless, the internal circuit of the load has been opened either through an open internal overload or an open winding.
    Steve Minnich
    EBEBRATT-Ed Member Posts: 15,629
    edited November 2016
    If you can't turn the impeller easily it's bound up. If it turns easily set your multimeter to ohms (with the power shut off and the motor wires disconnected) and read between the two wires you should read a resistance.

    Then ohm each motor wire separately to a good ground (cold water pipe) you should read 0 ohms. When it is pumping the amps should be at or below the nameplate amperage
    JUGHNE Member Posts: 11,077
    edited November 2016
    How about each motor wire showing nearly infinity ohms to ground. That is each wire should be completely insulated from ground....zero conductance to ground......I know what you mean Ed.....I have said this also.
  • bluemoon
    bluemoon Member Posts: 40
    Hahaha steve....if I could understand your reply I wouldn't have had to posted to begin with....was hoping for some basic blue collar help...thanks for taking time to reply though...happy thanksgiving
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    edited November 2016
    Two quick tests.

    If you have a ball valve in the hydronic circuit, with all zones running, quickly close the ball valve. If you hear a tapering HIISSssss, you have flow. If you hear nothing, you most probably have little to no flow.

    Other check is performed with the burner off, and the pump on. Hold a lit torch against the pipe for 5 seconds. Wait 5 seconds, then carefully touch the pipe. If it's hot, there is no flow. If its cool, there is flow.

    When using an amprobe to check motors, one has to be careful. A locked rotor on a 007 draws the same amperage as one that is running correctly...


    There was an error rendering this rich post.

  • doughess
    doughess Member Posts: 28
    Starting with electrical tests is not the way go. There are many mechanical issues that can mess up a pump that has good electrical readings. i.e. clogged ports, impeller issues, etc. Pull the pump visually check it, turn shaft and run it briefly.
  • Zman
    Zman Member Posts: 7,573
    I think the OP (last November) was looking for tricks for troubleshooting without pulling circ.
    Some good info was provided....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Steve Thompson (Taco)
    Steve Thompson (Taco) Member Posts: 204
    Typically when out on a troubleshooting mission I will touch one end a long screwdriver to various locations on the circ and other to my ear - makes a great stethoscope! If the circ is seized or the bearings are worn out you'll hear it. You can also "hear" flow. But be careful with mechanically sealed circs/pumps as there may be exposed rotating components that you do not want to get clothing, hair or neck ties caught in...

    Mark's diagnostics work well too. BTW, infrared heat guns are much cheaper than in the old days if you don't want to touch the pipe.