It is located in the kitchen in the same place where it has been since it was installed, 15 years ago. Note never had a problem until a week or so ago.
Thanks for the reply for you have confirmed what I thought the problem could be. I also suspcted the controller and if I had a schematic I would attempt to diagnose the problem further (I used to design electronic systems) I am aware that the controller is £230 etc. I will now have to replace the beast. Thanks again for your straight forward answer.
My pleasure Phillip ~ would you now kindly rate me serviced to you using the smiley faces below, this lets me shut down the job on the system. Many thanks and look forward to seeing you again on JustAnwer ~~ Ian