I have a Potterton Profile e60, in the morning i get a big thud which rattles all the pipes (like a big bang) waking everyone up in the morning...( i am not a morning person..) I have worked out that the noise occurs when the hot water in the tank has reached the correct temp. I can make the bang happen when i turn the dial on the cylinder thermostat high then drop it back to normal, there is a winding noise from the 3 way valve and the a big thud which rattles through the pipes in the area. HELP HELP HELP....