Singing noise related to water pump

[benawhile]

Since our central heating system was upgraded in October we have noticed a singing noise in the house when the water circulating pump switches on. It is a new Grundfos UPS2 15-50/60 pump with 3 speeds. Reducing the speed reduces the noise but it doesn't go away, and we need to use the maximum speed to heat the house effectively.

The noise sounds like a musical tuning fork. It comes from any part of the house where there are pipes or radiators, as well as from the pump, but is not easy to pinpoint. It is not loud, just annoying. How loud it is depends on where you are in the room and what direction your head is turned. It is as though the noise from the pump transmits to the water everywhere in the system.

The system works well otherwise, there are no other clues, although there is a slight unrelated whistling from the boiler flue which is being investigated.

A Magnaclean filter was fitted and has removed about a cupful of black rust already.

 

[fixitflav]

Was going to post a picture of the label but assume not needed now!

That's right. As I said, I doubt it would be relevant to your problem anyway.
BTW, have you managed to cure it?

 

[benawhile]

Will need a week or two to try options and discuss with installer thanks

 

[benawhile]

Problem solved. Singing noise completely gone. Plumber replaced the Grundfos with a DAB 40-70/130. Whether the Grundfos was faulty or there was an incompatibility with my system we will never know. Thanks for all support.

 

[chris watkins]

Problem solved. Singing noise completely gone. Plumber replaced the Grundfos with a DAB 40-70/130. Whether the Grundfos was faulty or there was an incompatibility with my system we will never know. Thanks for all support.

Interesting & nothing else was done to the system ?

Thanks for letting us know as others may come across the same thing.

 

[benawhile]

Nothing else done according to the plumber.

 

[fixitflav]

Interesting & nothing else was done to the system ?

Thanks for letting us know as others may come across the same thing.

Interesting, as you say!
I used to think Grundfos were the best pumps going, wouldn't have anything else, but a doubt or 2 is creeping in. The original UPS 15-50/60 I believe was made for 30-odd years, but the UPS2 only 2-3 before being superseded by the UPS3, and I've heard odd reports about the UPS2, one being that if it is powered via the boiler (for overrun) it can fry the pcb. I fitted a UPS2 about this time last year (before hearing the rumours, and it isn't run via the boiler) and it's been OK, but there is a slight singing noise, maybe like the OP described. Unnoticeable during the day, but at night though it doesn't wake me, if I wake I can hear it. And it doesn't happen all the time. Had it on minimum fixed speed, and thought it would be better on PP - slightly lower flow. Set it on on minimum PP and it was worse, went back to fixed. It's nowhere near bad enough to warrant changing the pump, but it's made me think.