Strong vibration foghorn sounds in system

[jklondon]

When we turn on the water first thing in the morning of after a while of non use there is vibration sound that can be heard to different degrees across the house.

Its not instant but normally after a minute when the water has been turned off.

It doesn't seem to be isolated to a particular faucet which is making it hard to isolate. However we had the expansion vessel changed in the summer due to another issue so my thinking is that its the culprit but not 100% sure.

Any guidance welcomed.

Thanks
Rav
NB - trying to insert youtube links for videos but get the spam alert on this forum

 

[Chuck]

Assuming your system has an unvented hot water cylinder, what you are describing is probably due to the pressure reduction valve (PRV) not closing smoothly and positively. Needs a plumber qualified to work on unvented systems ('G3 qualified') to investigate.

 

[Munday]

I have had same fog horn noises but could not associate with any change other than new water meter added and the cold water was turned off.

Try this close off cold water mains and drain the cold and hot water pipe work. Slowly open cold water mains gradually with all taps open and gradually close taps so all is expelled from pipe work. Do not speedily open the cold water mains but open it gradually allowing the trapped air in the pipe work to escape. Also do not open the cold water mains fully, only open it so there is sufficient water pressure for normal use.