got a worcester 280 boiler and heating has stopped working the domestic hot water flows and boiler ignites in DHW mode but in heating mode the fan kicks in you can feel pump reverberating boiler ignites for 10 seconds then clicks off! the overheat stat is not tripping out so does not have to be reset, but pump gets very hot in the 10 seconds its on for I believe its the pump but has anyone had a similar problem and found it to be something else?