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Whining circulator pump

One of the main circulator pumps (Grundfos UPS26-99FCF) for my boiler makes a medium pitched whine ever since the system was installed. (See photo--lower of the two pumps) .The sound radiates up to the first floor and to other rooms in the basement. I do audio recording in the basement and the noise is intrusive. None of my other circulator pumps make any noise at all. The whine decreases when the switch is set to "Med" and essentially disappears when it is set to "Lo".

I am trying to decide whether it is worth replacing the pump. Any opinions? Or is it possible this is something intrinsic to the system? For what it's worth, the other circulator pump (top one in the photo) makes no noise at all.

Appreciate the help


  • Jason_Talbot
    Jason_Talbot Member Posts: 22
    Wider angle view of my system:

  • hot_rod
    hot_rod Member Posts: 22,254
    Noise in circs can be from air problem, mis-applied, running off curve, restriction in the Piping, or a bearing failure.

    How was the pump sized? Did the noise just start
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jason_Talbot
    Jason_Talbot Member Posts: 22
    thanks. noise has been present since it was installed.
    system has functioned well for 3 years otherwise.
  • ch4man
    ch4man Member Posts: 296
    thats an awful large circulator for a veissman that has the OEM low loss header.
    maybe running it on low is the correct speed