You don't appear to know about PID's, they're used extensively in the process control industry. It's a kind of smart switch that can predict the heating latency of your electric element (for example). This functionality makes them unsuitable for traditional switching (like a fridge compressor) because those devices don't work well with their power being pulsated every few seconds, but an electric element has no such problems and it works beautifully for sous vide cooking. In fact, basically all immersion circulators are PID controlled. Some of them can have a whole heating cycle programmed, as you described. Some can control a heating element and a cooling device. Some are hardware boxes, some are just software. http://www.auberins.com/?main_page=index&cPath=1
