Brian-Gaff wrote on 13/05/2018 :
I don't know what hers is, so cannot comment. I was led to believe the pump
was renewed at the time and yes, its upstairs in the airing cupboard. In
which case she has been unlucky. The thing is it has made this noise since
new and the folk who put the system in claim they all are like that.

I have only ever come across noisy CH pumps, which are faulty/ falling
apart internally, otherwise near silent. No they are not all like that,
people usually fit new, not because they have failed, but because the
pump ha become noisy in operation. Someone is certainly telling
porkies.