I posted a complete working arduino sketch in a thread called data logger ( page 2 ). That should give you a good feel for what they look like. It reads 4 sensors and controls a pump relay, as well as logs the data to USB. http://www.hearth.com/econtent/index.php/forums/viewthread/48079/P15/ It is also included in a download file on the Hearthwiki I put some trending logic in it in preparation for a variable speed motor control. Trending hotter = increase speed by one, trending cooler decrease speed by one. Mostly tweaking the start/stop logic to get the most out of what I have. Nice looking enclosure , this stuff is addicting.