I moved into a new house a few years ago and slowly made it smarter through the Apple Home ecosystem. The house has three thermostats that need to be changed. The central thermostat is a 1990s era Honeywell and has a programmable basic schedule. It controls AC for the whole house and heating for one of three heating zones. I'm sure this can be swapped out for a smart thermostat as it's very similar to the one I replaced with a Nest in my last house. There are two other thermostats in other areas of the house to control the other two heating zones. These two appear to be very old "RAPIDE" dial thermostats made by Honeywell/ICP. I believe they are original from 1964 when the house was built. [Here is a photo of one](https://i.imgur.com/apJjnMp.jpg). I think it works on line voltage? Each of them has only two wires. If it matters, the heat in the house is generated by a 1964 gas boiler that runs heated water through the baseboard radiators. I'd like to replace all three thermostats with smart models (ideally Nest, now that they support Apple Home through Matter and are often on sale for as little as $10 through my energy supplier, compared to $100+ for the EcoBee models), but I'm afraid the wiring on my two heat only thermostats may be too old and not compatible with smart thermostats? Hoping for some advice from the experts here. Can I replace these older thermostats with smart ones? And if so, are there additional steps to be taken? I also have a heated enclosed patio that uses a completely separate electric baseboard system and I'm thinking of replacing it with a Mysa brand smart thermostat. Does anyone have experience with this brand?