I have an old boiler - must have been fitted when the house was built in the 1980's. Don't know what it is but in order to get hot water I have to have the heating on if there is none in the tank. Anyway, down to the heating, after I have switched I on for about an hour the pipes bang in the walls. If I have run a bath then I can have the heating on for longer before the banging starts, so I am assuming the banging starts when the water tank has reached a max temperature?? If I keep the heating on through the banging it eventually quietens to more of a whirring sound. Can anyone help? It's costing me a fortune turning it on and off and is freezing in the morning! I have tried bleeding the radiators, no air is coming out.

Boilers are designed to be turned on and left on for the season. You might try to bleed the system of air since that is one of the signs of banging. It would also be good for you to post pictures of your install since it might help for us to see exactly what you have.

Thank you - I've attached some pics of the boiler and water tank for you now.