In an earlier contribution to this discussion,
Fred wrote:

On Sat, 2 Feb 2008 15:20:47 -0000, "Roger Mills"
wrote:

Probably close to the pump and valves in the airing cupboard. If
*these* wake you up, there ain't a lot you can do!

The pump is nice and quiet. The valves do whir when they switch off.
Only time will tell if that becomes a nuisance. Perhaps the system
should have been designed with them in the kitchen? Too late now, or
could they be fitted to the return pipes? That's more of an academic
question; I doubt they will be a problem with the doors closed.

Thanks.

The whirring is from the gearbox. The motor drives the valve through a very
high reduction gearbox. When the valve closes, using the spring return, the
gearbox then becomes a high ratio step-up jobby, driving the motor round at
a fair rate of knots.

Whilst you *could* put the valves on the return side, it is far more usual
to do as you have done, and to have them on the flow side immediately after
the pump.
--
Cheers,
Roger
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