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Circulation pump vibration noise?

Hey there,

My wife and I recently purchased a house with a baseboard hydronic heating system. Whenever the circulation pump kicks on, it sounds as though there is compressor starting up outside. It is a dull, deep vibration noise throughout the house. During the day, the noise is hardly noticeable, but at night, it is waking us up.

The pump also cycles a few times for about 30 seconds before it starts a longer pump cycle of about 3-5 minutes. This seems odd to me. Is this normal?

We had a heating technician come and service the system, including a drain and bleed. We addressed the noise issue with him when he was here, but he said that the pump was "fairly new".

Any help would be GREATLY appreciated!

Thanks so much.



  • RJ_4
    RJ_4 Member Posts: 484

    could be a loose or broken coupler if its a B&G series 100 pump or taco equivalent , or a bad motor or pump bearing,  it most probably will get worse.  Better have a pro look at it.  have the pump brand, mod, serial # and motor horse power  on hand when you call.
  • Grundfos pump

    Thanks for your reply.

    The pump is a Grundfos UPS 26-99 FC model as an FYI.

    Thanks again!

  • RJ_4
    RJ_4 Member Posts: 484

    Get a tech to check for pump cavitation (air in system getting into pump )  beftore replacing pump.  this is what is called a maint. free pump, no coupler.  If the pump is within a year old  it should still be in warranty.
  • Jack
    Jack Member Posts: 1,047
    Spring check valve

    Check to see if you have a spring check in the system. Under some circumstances the seat will "flutter". Water being non- compressible the system will speak to you. I've been called out on a few systems where I found this to be the problem. I've seen a Bonomi spring check fix the problem, if that is your problem.
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