80f shuts down having operated normaly somtimes for days.the shut down occurs when the boilor starts to make a kettling noise.other than the water not circulating in the system correctly (new grumfoss pump fitted 10 mths ago), any ideas which boilor component could be causing this problem?

paul, August 2010

new thermostat fitted now works a treat.

paul p.s. this was my question, September 2010