Hi i have a problem with my ferroli 77ff gas combi. The problem started lastnight.The pilot is alight but when the hot water is turned on the fan kicks in but the main boiler does not ignite,same as if you switch it to heating/water on constant on the selector switch.I have also noticed that the fan blades that you can see have hit a tube and broke off but i dont think this is the main problem.If anyone can help it would be much appreciated. jim.