My heating system was drained and new radiators fitted, with new pipe routing in some cases. The boiler fired up fine but only run 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. 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. The boiler runs for approximately 4minutes each time. Any advice would be greatly appreciated.
The Oil boiler is a Myson presure jet 50/70 and there is what appears tobe a thermostat dial that connects to the electricity supply and boiler, but it reads clockwise minus 15 to plus 10. What does this do (if not a thermostat) and what position should I set it to