Dear Steve:
I don't know the exact amount of heat capacity but roughly about 200cc water ( I think 100 W-100joules/Sec - is enough for the purpose).

I downloaded an excellent book for 5 USD on PID control using digital methods. I'll try and find a link to it.
thank you very much indeed. your reply implies also that you hadn't use standard text book algorithms for your commercial product(correct me if I'm wrong).


thank you very much indeed