Hi, this is my first post on this forum site and I am hoping to get some advice on the following problem. The house I bought last winter has a Potterton combi 80 boiler and worked fine. The central heating has been turned off throughout the summer. I turned it on for the first time the other night and the following problem occured. The boiler knocked and banged a bit, possibly a bit of air in the system? but after 30 seconds steam/hot air and the odd splutter comes out of the top of the boiler and then shuts down. The system then tries to start up again but goes into 'Lockout' After looking for any obvious problems - bleeding the radiators etc... I found there was no pressure in the system. I have re-pressurised to just above 1 bar and re-bled the radiators and started it up again but the same thing just keeps happening. I have done this about 6 or 7 times now. The system pressure does not change much when the steam is being released, it just stays around 1 bar. Any thoughts are appreciated as my plumbing knowledge is minimal.