Thanks Tony for your prompt reply,The pump sounds as though it is pumping but not sure,it is getting very hot though.
I have not checked the header tank but will do so.
I have a conventional hot water system.My boiler lights up for about 2mins and then cuts off,it then wont relight until it cools down again,could it be an airlock in the system and if so where do I bleed it from.It is a Gloworm.Please help.Thanks.