Thanks for the comments. I need a couple of days to put together a tour of the controller, sensors and other devices. The software used with it is very interesting. There is a couple of problems for me with this setup though. First is if the controller went bad I would not be able to afford to replace it. It was given to me by a mechanical contractor that removed it from a demo job. The second problem is the software used with it is also expensive. As long as I’m working with this product line on the job – I have use of the software. But that could change. So this controller is kind of a dead end as I cannot replace, duplicate or expand it. The good news is that this type of controller is very common in the HVAC industry. They all do the same thing. As manufactures come out with new generations the old stuff shows up on places like Ebay as upgrades are made. If you are hard core DIY then you can build your own.
http://www.nutsvolts.com is a good source of info (lots of programs also). Checkout the articles on the basic stamp. Start simple – like a heater controller. In a few years tank computers will be allover the place (especially when china starts making them). But for me the best part is the DIY.