Got a SX20 Maffice boiler installer and recently when i turn on a hot tap there is a loud vibrating noise which, with the help of the diagram i have pinpointed to the gas valve area, near where the plastic pipe attaches before it runs up to the combustion chamber i was wondering if anyone knew what may be causing this. It seems to dissapate and stop when the water gets to temperature. Please help, i need to get this sorted before my partner drops our first child! Any more info required please ask