I have done that three time already, but the plumbers can only say it's a standard problem with Potterton Puma 80 circuits which go loose. Have called another one this evening, so let's see.
I moved into my new house last August. Since then, my combi-boiler has been causing trouble. It suddenly stops firing gas when HW or CH is turned on. The old style knocking seems to revive it occasionally, but mostly it stays inactive despite the best of my efforts. Of late, I hear loud hissing...