Owww... PID control is fine to implement but tuning a PID control system is a very complex thing. The rules vary from system to system and you need a lot of experience to get it right.

If on-off control suits your purpose, stick with it. Doesn't really make sense using PID for a simple application, its overkill.

If its information on PID you want, do a search (on Google, or even on this site). Seek and ye shall find! ;-)

kundi