Thanks CBW.I will have a good look at the wiring and report back to you.Much appreciated for your time.Ok Dal, let’s try and break this down: at any point were you able to have separate heating, separate hot water or both (mid position)? Obviously you have a wiring fault,but could have always been like that including the programmer. If you are like me and stubborn until it’s fixed then providing you can work safely maybe check this out:
Y Plan central heating system
Dal