noise from cold water feed pipe into header tank?
 
                when I open the hot water tap (any one in the house) after a few moments there is a very loud vibration through the cold water pipe as the ball valve in the header tank starts to deliver water in to re-fill the tank,I have had the washers replaced in the valve unit and have had a plumber just fit to-day an air cushion pipe to the pipework at the tank but still the problem exists. Please can you help ?
            
             J.R. Mac
            
 August 2009