we use economy seven for hot water as we have storage heaters throughout the house. recently, we find that any time exceeding the one hour boost, say,causes the hot water in the header tank to bubble up profusely,the water being very hot and splashing the walls.we also have quite noisy vibrations when using the tap, not sure if this is related. the thermostat on the boiler has been reduced to 50 degrees but this does not appeat to have helped the bubbling problem. any suggestions please ?