I had a similar issue with a neighbour's central heating pump. It
reached the point where one bedroom was unusable because of the noise
transmitted through the party wall. It was nowhere near as loud on her
side (different layout of rooms) and, as she is a tenant rather than the
owner, it wasn't resolved until the pump failed. I bore you with that
background only to lead on to a possible approach: say that you are
hearing a noise which might mean her central heating pump is about to
fail. That would leave her without heating in mid-winter. If so, much
better to find out now and schedule a replacement.
--
Robin
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