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Hydronic Water Circulator

Chris_78 Member Posts: 6
My boiler has a Taco circulator. After installing two new cast iron radiators I filled the system and fire the boiler to test for leaks. The radiators heated up. But then the heat stopped. The circulator was still making a humming noise but the pipes not far from the boiler were not hot. This circulator is one year old. What could be wrong with it?


  • Brad White_9
    Brad White_9 Member Posts: 2,440
    A few things come to mind

    1. Debris jambing the impeller

    2. Air-bound

    3. Motor seized (similar to #1)

    If the circulator is hot, that is normal when operating continuously. Is it in itself hot?
  • Joe Mattiello
    Joe Mattiello Member Posts: 703

    Good Morning
    As Brad White mentioned in his correspondence, second bullet, the system could be problematic with air. If there was an air pocket in the system and it made its way through the system, and back to the circulator, the circulator will stop pumping water but continue to run. At this point most people will assume the circulator failed, and return it to the dealer. Always validate the circulator before concluding the circulator failed. At this time you may also see a rise in operating temperature because the circulator relies on the medium being pumped to cool the motor, and lubricate the sleeve type bearings. The circulator is designed to run at temperatures up to 240 degrees continuously, so don’t be concerned if you can not hold your hand on it. Most people use the hand as a thermometer, and call the factory when they can’t hold their hand on the pump. Anyway, try repurging the system, and that should remedy the problem.
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • Chris_78
    Chris_78 Member Posts: 6

    Thanks for the responses. I believe that you guys are correct about the air pocket. I'm going to install on more vent in the radiator where I feel the problem may be stemming from and attempt to purge the air from the system. Thanks again for the help!
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