Hi I need help to try find a solution to my central heating. I have a potterton back boiler fitted was here when I bought the house. the programmer is the controller for heating and hot water and I have 2 thermostats 1 for the hot water and 1 for the heating. Everything works for the hot water including water pump and boiler but nothing works for the heating. The programmer lights up when the heating is on but nothing registers can someone help. P.S I have replaced the programmer same result.