Problem with Grundfos Alpha+

[stem]

The pump is located in airing cupboard between two bedrooms. In the morning the pump has started waking everyone by making a loud buzzing noise, that is pulsed, a bit like someone sawing a plank. The noise is also transmitted to the radiators in the adjacent rooms that act like loudspeakers. At some point during the day things revert to normal and silence is restored.

I purchased this pump 2/3 years ago, even though it was twice as expensive as other makes because it was recommended to me by a plumber. I was replacing an old myson that had become noisy and I stipulated I wanted a good quality, quiet pump, and it has been... Up until now.

Moving the control switch to manual speed makes no difference. It's still working perfectly, it's just the early morning call I could do without. Any ideas?

Here's the associated system info:
Grundfos Alpha+ set to automatic centre position
Open vented (tank in loft)
"S" plan
Auto by-pass (Normally open motorised valve, closes when boiler runs)
Boiler - Baxi Solo (non condensing)
9 Radiators, 8 with TRV's, one without
One towel rail

Thanks in advance

 

[Deleted member 105431]

they are the best pumps you can get. check the bypass isn't turned off and the system (and pump) are bled of air. check header tank in loft is full.

 

[gas4you]

Alphas of this age are known to be problematic. Faults have been addressed in the new ones sold today.