My boiler will start up but after a short period of time about 4 to 5 mins it goes off and will not start again for about 30 mins, i have tried to start it with the pump turned off ans same story and i turned off all the rads in the house as i read online to do this and turn one on at a time etc but again same result the boiler turned off again and the red light is gone off. I also did bleed each rad with the key and let out all the air multiple times. Thinking it might be the thermostat but could be wrong.. Any suggestions greatly appreciated.

ken, December 2017