Potterton Netaheat boiler?

I have a potterton netaheat boiler and when I moved into the house there was a timer switch fitted which separates the heating and the hot water. The hot water is set to come on at 6am but the radiators are coming on as well even although the heating is switched to off. I recently had someone out to move a radiator and the system had to be drained and I wonder if this has something to do with it?