Hi I have a fully pumped system. CH hasn't been used since April. Last Friday was a bit chilly so I turned the room stat up but the boiler didn't fire up. Boiler works when I demand HW. I installed a new room stat (Drayton RTS8) which made no difference. I then changed the controller from a Potterton EP2001 to an EP2 but that didn't solve the problem. I'm out of ideas. Can anyone suggest the next course of action please? Edit: Boiler is a Potterton Profile 40.