I have a Bryant heating and air system. The digital thermostat will not come on--it is blank. I have checked breakers. Power is coming into the indoor and outdoor unit. I understand there is no reset and I checked the fuse in the indoor unit. How do I check thermostat? Any suggestions appreciated.

I am planning to build a 2200 sq. ft. lake house in the next year that will be split up 3 ways. The main living area is about 1500 the upstairs guest room/bath is 300 and the game room is 400. I would like to install a chilled water system in the house that will be easy to manage the different zones. I plan on having 2 condensing units for the system and 4 or 5 air handlers. I am a controls technician at work so the control scheme will be easy for me. I plan to put the system on PLC, analog control and thermocouples for sensing room temp. To learn about what I need to do I would like to start now doing testing. I have a spare 3 ton condensing unit that I would like to build a heat exchanger for. I plan on using PVC as the outer shell and copper tubing with an expansion valve attached to one end. What I an not sure of is what size copper tubing, how long does it need to be and what is the smallest diamater it can be bent to by wrapping it over a round pipe or pvc pipe. any feedback would be appreciated.