When i turn on my Glow worm ultimate gas boiler it works perfectly for a while (water heats up and radiators heat up) then it pops the overheat safety out. The boiler casing is very hot to the touch but the thermostat seems to work as it will cut it out if turned down manually. Any ideas?
Check your pump and make sure you have vented all the air from the system, could just be that the boiler thermostat is out of calibration, try operating it at it's lowest setting and see if the over-heat cuts out then.