if the arduino crashed then everything would be set to power down and the flame would burn out? not ideal but the chance of anything catastrophic happening would be pretty slim i would think.
If the arduino crashed there would be no fuel
so what i need to do goes something like this:- purge air fan (xxseconds) then off, glow plug(xxseconds) then off,fuel pump (xxtimes)then off, then the fan starts slowly the fuel ignites and the fan builds up speed slowly. so i also need to know the fuel has ignited(flame sensor signal) and if not we start again, this didn't seem so complicated in my head but now i put it in writing it seem daunting, the over heat and temp sensor would provide a input to stop the fuel, seems fantasy at this time but i would also like 3 temp settings ( fan speed and fuel pump) and a programable timer :-/i like to jump in there its the only way to learn !!! hope you guys can give me a starting point. forgot to mention the water pump which just needs a 12v on/off
Robin2 posted a working example sketch a while ago which demonstrated a good way to implement a finite state machine and manage timed actions.