On 28/01/2021 18:22, Andy Burns wrote:
Peter Able wrote:

Twice this year the house has been shaken by drumming - sounds, and
feels, like a helicopter just overhead!Â* I've managed to stop it by
opening the drinking water tap for about 10 seconds. What's causing it
and what's the remedy?

Water hammer, can be started by a rapid shut-off of a tap or e.g.
washing machine solenoid valve.

Thanks Andy. This happens when nothing is happening in the house's
plumbing - not even a cistern refilling after a flush. Plus it can't be
relieved by opening any tap but the drinking water feed tap. Nor by
flushing any cistern. I've been down this paths.

It is audible outside the house at, roughly, where the water supply -
both direct and indirect - enters the house.

PA