With thw boiler switched off
Take the plastic cover off the microswitch on the side of the diverter valve. Turn on the hot water tap. Look to see if the diverter valve pushes out to press the switch. Mine wasn't coming out far enough to press the switch so never fired the boiler for hot water. I dropped a rubber washer in front of it and it now works. I will clean out the diverter valve at some point as this is the cause. (In my case)
Nick
January 2012