My Worcester Highflow 4.5 boiler is acting up and I wonder if anyone can advise me. The hot water and the heating have gone off, but the pilot light is still lit. I turned the hotwater temperature up higher than usual and now have hot water again, but no heating. I've checked my radiators and they don't have any air in them. Which components could ne causiong the fault? How can I check they are / are not working? In advance Thanks Dave