I have a Micro DRIVER 2H pilot wire system (made by Delta Dore) that controls my cental heating. As I'm not in my flat that often, I haven't been using it to control my heaters and have just been using them individually when required. It is powered by the mains, but I have recently noticed that there is now no power to the pilot wire. There is a small 3 amp fuse in a panel next to it that I replaced, but the system seems to blow the new fuse each time I replace it. Any ideas what is causing this, could there be a problem with the wiring somewhere? The flat is a new build and only 2 years old.