Ok I have looked extensevly on here and have found some good answers to my questions however none of them work. I have replaced the thermostat as I needed a new one anyway, I have also replaced just the box to the three way port. Hot water comes on perfectly with the timer but central heating will not come on at all. programmer light comes on for central heating but nothing. can not here the motor making any noise at all. I have checked the wiring with a multimeter which I get 240 with one end to live other touching another wire until it comes to the grey wire and to get a 240 reading I have to put the red terminal on the neutral. View media item 83332