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Comment by kayodelycaon | Hacker News Reader

Interesting. Unless I’m missing something, my Honeywell T9 thermostat already handles most of this. I’ve got 4 remote sensors hooked up to it. It’s fully programmable without any app. (I think it needs WiFi for initial setup, but it’s been fire-walled off since.)

It also connects with home assistant over Wi-Fi. Combined with my home-kit window AC unit, I have full control over scripting, with the thermostat able to operate independently if Home Assistant fails.

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When I got my new HVAC system installed a few months ago (heat pump, woohoo!), they needed to upgrade my thermostat, so they gave me a Honeywell VisionPro 8000, which is a "smart" thermostat but, like your T9 (I think), demands WiFi and some garbage "cloud" service to access the connected features.

I replaced it with a T6 Pro, a thermostat which is by all other metrics a downgrade, but which has a single killer feature: Z-Wave. No phoning home, no janky embedded devices on my WiFi network, just a solid integration with Home Assistant that falls back to a regular thermostat if my HA server is down.

Seems like Honeywell is moving away from making Z-Wave versions of their products, because I think most consumers are generally content to tunnel their request through some shitty cloud thing every time they want to turn the heat up... but for those of us who are a little more ideologically rigid about keeping their stuff LAN-only, would definitely recommend grabbing a T6 Pro while they're out there.

As far as I can tell, the only T9 features needing an internet connection are local weather, geo-fencing, and remote control.

WiFi isn’t necessary and can be turned off. Quite a few settings can only be set on the thermostat itself. It has an on-screen keyboard and by its appearance, I think it runs some version of android. :)

That's my approach to heating as well - I'd rather not have Hass directly control the boiler/radiators with relays since in case of failure you could have the system either stuck on or off. A network-connected thermostat where Hass merely sends commands to is better since it will still retain some functionality should Hass fail.

I have T9s as well but the Z-Wave variant. Mine are more like traditional digital thermostats with thresholds and momentum compensation but it's all manual and not self calibrated. You can however program them via Z-Wave so you could use Home Assistant to do the Smart part.

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