Ok, I had a look at the furnace and it looks pretty complex in there where the fan unit is. There is a circuit board with about 50 wires plugged into it and i would have no idea at all where to connect to it. I installed the furnace back in 2002 and all I had to do was connect the two wires from my existing thermostat to the screw terminals on the circuit board. There are other terminals, most likely for air conditioning, which may be the solution to my problem, as if I understand it correctly, you have a similar installation with a coil (Heat/Cooling exchanger) For central A.C. So something has to trigger the blower fan to run for the A.C. So can i just connect the 24 volts going to my 3 way zone valve to the terminals on the circuit board that would normally be used for cooling? If that is the case, Which terminals would be used and how would it be wired? I have no problem with using 2 T stats, I just am stumped as to how to wire it into the furnace. I did figure out how to speed up the blower for the heating coil, (just have to switch two wires) I see where one is labeled heat and one is for cooling. This is the only thing I am having a problem figuring out. the rest has been pretty straight forward. Can I steal power from the existing thermostat to power my second T-Stat? Lots of questions.