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Stuck circulator

John Pipkorn
John Pipkorn Member Posts: 12
in THE MAIN WALL
Just wanted to throw this out there, I went on a call on a Knight boiler we installed this past summer. They said it was making a banging noise. When I got there and watched the thing start up, it did indeed start to rock and roll, it sounded like there was no flow through the boiler. I have this little magnetic device I got at a seminar on Grundfos and it has worked great to confirm that a pump is spinning. You hold it up to the back of the motor and it spins if the pump is working. I have had several instances when this thing has indeed shown a non functioning pump. When I used it on this situation, it showed that the pump was turning (Taco 0011). I found the amp draw a little high and the motor was too hot, upon pulling the thing apart, sure enough the impeller was stuck tight. Anyone have any thoughts on why my little indicator let me down? Thanks
John

Comments

  • Southside
    Southside Member Posts: 20


    Your indicator probably detects the rotating magnetic field of the motor. As long as the field is there it'll spin. It can't actually tell if a rotor is stalled.

    Whoever ran the seminar should have mentioned how the darned thing worked so you'd know how far to trust it.
  • Derheatmeister
    Derheatmeister Member Posts: 1,579
    Wrong circ

    The Magnetic Tool that you got does not Work with Taco circs but it's great for Grundfos circs.
  • Unknown
    Unknown
    Stuck Circulator

    Southside is correct. The spinner key chains only prove a magnetic field. Viessmann gives them away to test solenoid valves - ain't anything spinning there except the field.
  • Heatman_2
    Heatman_2 Member Posts: 65
    knght boiler

    I also had a service call on a recent Knight install with the same banging sound in the boiler. Neither my boiler or system pump were running. Both pumps are wired through the same fuse on the circuit board, a 5 Amp fuse. My boiler had a PL 55 and a PL 45 both pulling almost 5 amps each. I rewired the pumps using isolation relays and have had no more problems. My distributor reported of other contractors having similar issues with the board switching the pumps directly.
  • Heatman_2
    Heatman_2 Member Posts: 65
    knght boiler

    I also had a service call on a recent Knight install with the same banging sound in the boiler. Neither my boiler or system pump were running. Both pumps are wired through the same fuse on the circuit board, a 5 Amp fuse. My boiler had a PL 55 and a PL 45 both pulling almost 5 amps each. I rewired the pumps using isolation relays and have had no more problems. My distributor reported of other contractors having similar issues with the board switching the pumps directly.
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