Well, the first part of my thermostat project is coming together. I’ve validated that I can power the Raspberry pi from a 24V AC source with what I’d consider minimal additional components. I’m still waiting for Adafruit to get the capacitive touch screen in stock but I believe this setup will be capable of powering the entire system. I created a forum thread for a brief “how to” on this topic. You can find it here. The next thing I will be testing are some relays that just arrived from Jameco which I’ll use to signal the HVAC unit to come on or shut off.