So this is a fun one - installing everyone’s favorite thermostat, the Nest.

I was a bit crunched for time so I didn’t end up getting as many progress photos as I wanted. This project also ended up being a bit more DIY than my last couple Nest installations, which were pretty straightforward.

First, removing the old thermostats. This has a ton of battery backup power for some reason.

Pictures of the wiring to tag stuff later for the Nest

Time to turn the breaker off. Typically, “FAU,” meaning Forced Air Unit, is the one you want. This switch controls the furnace/fan and thermostat wall units. The AC switch is for the AC unit and doesn’t need to be shut off.

Labeling wires

This is where it gets complicated

Behold this mess

Couple things going on here:

This is the wrong type of outlet box for this fixture. This box is for a single pole light switch, not a thermostat. That’s the biggest reason this turned more DIY than I expected. The old thermostat wasn’t actually using any of the screw holes from the box. There are 2 unused top holes and 2 in the center for the old thermostat.

I panicked a bit to try to figure out what to do since I was already over time, but decided that I’ll try using just the top screw hole in the box and see if that works.

Luckily I bought a third party trim plate large enough to cover up all the wall blemishes, otherwise I would’ve needed to spackle and maybe even paint (I hate painting). Carrying on… Needle nose pliers (pictured) and wire cutters (not pictured) are your best friends for wiring work. At this point I tried putting the screen on the base and the whole thing felt pretty wobbly against the trim plate as well as misaligned despite the level being in the center.

Panic again! 😖

I decided to take a crack at adding a nut to the back of the bottom screw hole of the trim plate. No more wobble. Crisis averted!

Went back to the breaker, turned the FAU back on, and… Success!

Weirdly, I had to adjust the screws and trim plate quite a bit to get the screen to level despite the bubble being in the center. Oh well.

No photos for the next part, but I pretty much repeated the same thing for the other thermostat. Similar situation except I had to use the bottom screw hole to get the trim plate to be flush with the wall.