Building a Mock HVAC for Smart Thermostat Demos

Update: I’ve added instructions for a cooling system at the bottom of this post. Recently I needed to create a mock HVAC system so that I could have a portable smart thermostat for various demos. I searched around but couldn’t find any such thing. So with some sleuthing and the help of my friend Bruce Eckel I was able to build a simple system that powers a smart thermostat and simulates a heating system.