I have a Potterton Combi 80 it's about 10 years old now and for the last few months when you turn the power on the boiler fires and carries on running for a few minutes. untill it goes into lockout this happens without hw or heating on.When you run the hotwater it runs very hot then lockouts after a while but enough to fill a bath.There is also a problem with the heating the rads heat up for about 5 to 10 minutes then boiler locksout.The boiler makes quite a loud noise near the top when it locksout after startup.
Any ideas please.
Any ideas please.