hi Mr Dowling take the front off the boiler on the bottom left hand side you will see the brass diverter valve its got about 8 screws on it. when you open your hot water tap you need to check that the pin that comes out of the middle is reaching the switch there are two on this so its not the one where the pin comes up vertical its the one directly in front of you. if its not hitting the switch then you need a new diaphram. thats your start point.
Brian Emian Plumbing & Heating, April 2011
