hi all, i have recently had a new combi boiler fitted and since then i am plagued with water hammer. i have researched this and some fitters are saying it could possibly be caused by the stop cocks i fitted to isolate various parts of the house and extension. i have read that fitting check valves could eliminate the water hammer. has anyone else tried this and with what success or dissapointment? i know this seems to be a common fault on new properties but my house is some 60 odd years old and this only started after the new boiler and stop cocks were fitted. thanks for any help provided, stanman