1. Downstairs bedrooms
2. Upstairs Master (the studio and office)
3. Downstairs Livingroom (the dining room and kitchen)
4. Upstairs bedroom (boys' room)
5. Upstairs Livingroom
One of the first issues that we noticed is that the thermostat for zone 3 is directly above a heater for zone 1. Another is that all the thermostats used mercury switches except for zone 2 which has a digital sensor. A third is that all of the bedrooms on one side of the house run warm even when the heat for their zone is not engaged.
I fixed the first issue a couple of years ago by purchasing a Nest thermostat that could use a sensor from a different location. The third problem seems to be due to the hot water pipes that run through the bedroom walls, but I'm not sure how to fix that. I was working on the second issue today.
In 2022, I bought a couple more Nest thermostats, but they weren't quite the same as the one I got for our dining room. By the time I got them, Google had bought out Nest and had a different system for its Google Home setup. It was complicated enough that I avoided dealing with them until today.
With Rowen's help, I managed to install the new thermostats in my bedroom and in the living room (which had two of the older thermostats). Apparently, I need to get an electrician to hook up a power connector at the main panel for the thermostats to make certain that they don't lose their functionality. I tried taking a look myself, but was more than a little baffled. We'll see how this works, but I've kept the old thermostats just in case.