Hi. Thermostats are expensive. I currently have this one, at my apartment.
I would like to replace it with one that connects to HA.
First, is this a good idea since I'm in an apartment? I'll obviously keep the current one, and put it back before leaving.
Second, what's a good one that is either open source or at least non internet based (but still works on HA)?
There is a z-wave version of that thermostat with the same form factor and clicks right into the same bracket: https://a.co/d/03PLsNtX
I have it and it works as you’d expect.
I’m pretty sure Honeywell has a WiFi version as well. The Lyric T6 i think. It also uses the same bracket and if you bring it in to HA with the HomeKit integration you can block it’s access to the internet and it is fully local and considered offline to Honeywell
There’s a couple zigbee thermostats on Amazon if you search that. None that i have used personally so I don’t have any recommendations. There is a super cheap Tuya one, but i haven’t had a ton of luck with Tuya zigbee devices being very good. YMMV
I ended up finding the CENTRALITE PEARL THERMOSTAT 3157100 used on eBay for about $30. It can either operate from the panel or through ZigBee, no WiFi. It is supported on Zigbee2MQTT. It works really great and I have had no problems with it. You can easily find a manual for it online too.
I've been picking up cheap used or Amazon warehouse Honeywell T6 pro z-wave thermostat. (Same as sue)
Been pretty good so far, but requires z-wave for any of the remote functions to work
They can be found on eBay for as cheap as $20 shipped for just the unit and no mounting plate, and since you already have another model it's a drop in.