Dave Baker wrote:

"Adam-the-Kiwi" wrote in message
ups.com...

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however, we noticed a fairly loud buzzing coming from the bathroom -
the radiator was vibrating and this appeared to be the source of the
noise. The radiator in the adjoining bedroom was also vibrating, but
much less so. The noise appears to be linked to the pump, but the
boiler itself does not appear to making any unusual noise.

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Try changing the speed on the pump. They are usually two or three speed and
a lower one for a while might let things settle down. Probably just a
sympathetic system vibration from the pump which has altered over the summer
as pipes have furred up or sediment has settled somewhere.

Thanks Dave - I'll give that a try (if I can work out how to do it)...

Interestingly, a hefty thump on the radiator in question has changed
the intensity of the buzzing.