I have an unvented heating system which is only 1 year old. When it was fitted they was allot of humming coming from the pipes. I called the plumber back and he fitted an inline valve which seemed to cure it. It has now returned and I cant locate the plumber. It happends on all the taps at different time of the day and even if I turn the tap off slowly it doesn't seem to stop it . Any ideas.
Cheers
Cheers