Thanks for the reply, Zeke! Upon further research, you’re right about wifi thermostats needing to be powered — the “battery-powered” thermostats use their batteries for backup power (if/when the power goes out).

My setup sounds similar to yours—have a in-wall furnace connected to a millivolt General Controls thermostat (full description of our situation). How similar does our situation look/sound to your situation/setup, and how difficult would the install / setup process be for an electrical novice?

As for the putting the thermostat in the wall, will your (and, presumably, our) thermostat have wires coming out from the wall? Is there to wire it up so that no wires are visible, short of ripping apart the wall?

P.S. Came across your post from someone on reddit who linked to it.