My central heating oil boiler keeps cutting out. It is a Myson Volaire Pressure Jet 50/70. The system was drained when new radiators were fitted, with new pipe routing in some cases. The boiler fired up fine but only ran for a few minutes before cutting out and initially only heated the pipes upto to the upstairs cupboard where the flow and return pipes start to go off to the radiators. I have bled the radiators and after waiting 10 - 15 mins fired the boiler again only for it to cut off again. The pipes are heating up further along the flow on each occasion I go through this process but the radiators no longer release any air when bled. The boiler runs for approximately 4minutes each time now. Also there is a thermostat ranging from -15 to +10 (never seen that type before). what should the setting be? Any advice would be greatly appreciated. - The oil flow is fine Is it an airlock? and can this be removed by draining the system out from the boiler ( which is the lowest point), whilst allowing the header tank to fill the system or does it need to be drained off completely first?