Installing a Nest Thermostat to control our Warehouse’s gas heater was trickier than I had anticipated. But eventually (and with the help of the Internet) I figured it out.
Originally I thought I’d wired in the c-wire correctly, but I was advised via email that the thermostat had a problem at some point that night. The Nest runs on batteries so it will work even if you’re an installation ignoramus. But on batteries your time is limited. The Nest menu has a wire detection system / screen so you can see what is going on- all the wires need to be blue and my c-wire was not. I found a tutorial online (after an excruciatingly long search) and was able to hook everything up correctly as shown in the top right. All is well now and the Nest has been working great for a few weeks.
Here’s a quick video showing how to use a Nest thermostat with your heat-only system: