@Sean-Brockest said: not sure what a node or controller is. I don't care how it works, really. A node would be a MySensors device (arduino with a radio module) with one or more of the following attached; sensor, relay, switch, or something like that. The radio module would talk to a gateway node that is attached to a computer running some kind of controller (Home Automation) software. If this one thing is all you are trying to do and you are not trying to set up other home automation stuff, you shouldn't need the whole MySensors setup. You could probably do this with just an arduino board, 2 DS18B20 temp sensors and a relay module. The only problem in that would be that you would have to program it for a certain temp differential and any hysteresis that you would want in play, and it would be static until you re-programmed the arduino with new values. There would be ways to set it up to be programmed as far as the set temps and the switching, but that would take a lot more hardware such as an LCD screen and some switches for programming. It would also make the arduino code quite a bit more complex.