thanks
have sorted problem.
we found a small drip on one of the hot taps. this was not enough to light the 'demand' light, but enough to stop Central heating from working!
fixed tap, now working...
I appreciate your efforts, an excellent forum! :P
I have a normally working potterton puma 80 boiler
woke up this morning, all normal except no heating!!
pressure normal, hot water normal. when switch on boiler switches on for 20 seconds then switches off burners.
I'll freeze tonight unless you can help me in the right direction.
[one thing...