I am thinking from some about a project where I can have fun applying and learning how to optimize a PID controller. My humidifier has manual output control that I can (with some hacking) hook it up to an output of the PID. This seem to me more gentle approach than using 0.1Hz PWN like in sous-vide machine. This is fine for a heater and humidifier may not survive too long if I pulse it on/off every 10 seconds.
The point is that the links are fantastic read and really inspiring where else I can go with this project – thank you!
Krzysztof