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I am planning to install a Grundfos Alpha+ 15/60 variable speed pump in
a cupboard in my bedroom.

The pump is used to carry hot water (at 2.9 cubic metres per hour max.)
from a low loss heater to the heating circuits in my house and will be
on pretty much all the time.

Can anyone tell me how noisy this pump is? My only experience is with
shower pumps which seem to be very noisy. I'm worried that the Grundfos
pump might keep me awake at night.

Thanks,
Martin


I installed an Alpha about a year ago. When the pump first turns on it will
run flat-out and will probably be noisier than your existing pump. Within 5
or 10 mins it will slow down until it reaches a point where the pressure
drop across the pump reaches a certain value which is controlled by the
rotary pot mounted on the side. I have mine set to mid scale. The pump
cannot be heard at all, even when you are close and are listening hard.
(this of course assumes there is no air in the pump - that would make quite
a racket).

IMHO because of the nature of the pump operation, for minimum noise it needs
to operate continuously, the room temperatures being controlled by TRV's on
all the rads. If you fit it in a conventional system where the pump is
controlled by a room 'stat I believe it will be a lot noisier in operation
as it will be running flat out everytime the stat switches on, and will
never have time to settle.

In my particular set-up (I no longer have a single controlling stat, just a
timer in circuit with the pump) I am extremely pleased with the quietness,
and the general heating efficiency of the whole system now seems much
improved.

HTH

Quiche