We have a mains pressue hot water system (Ariston) which worked brilliantly when we first moved in. We could run a bath and shower at the same time no problem.
Then my partner accidently put the wrong salt into the water softener (flakes instead of cubes), and the 3 way valve (with the strainer on it) starts to vibrate every time we flush the loo. The hot water pressure has also gradually dropped.
Do you think the valve needs replacing?