I use a z-wave thermostat (Honeywell T6 IIRC). If you want to avoid the cloud WiFi probably isn’t what you want. I’d look at z-wave or zigbee models. Some thermostats also require a common wire (C-wire) which means they’re powered by the HVAC system itself rather than using batteries. This is especially true of WiFi models.
this post was submitted on 19 Oct 2025
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Seconding the t6. It's been solid and does everything I want in HA.
I even got a rebate from my electric company for the full price of it which might be worth looking into.
Had mine for a while now and it's been rock solid. Love it.
I use esphome & a 4 channel relay to engage the HVAC stages. I built a virtual thermostat in home assistant and tied it to a Shelly e-paper temperature sensor. I can move it to other sensors in the home if/when needed or carry the sensor around the house. It's not a huge place though.
I have the old school thermostat still on the original mount point in case of catastrophic failure and for aesthetic.
This is the way. The ‘smart’ is already in home assistant. You need a temp sensor (or a few) and the actuators to trigger the HVAC equipment. There are numerous ‘smart thermostat’ integrations already and modules that handles the PID math for those who want to roll their own.
Any third party product with code you can’t inspect or replace is less secure. In this case, there is no compelling case for a commercial product.
I built a virtual thermostat in home assistant and tied it to a Shelly e-paper temperature sensor.
This is interesting... I hadn't even considered that possibility...
example link there's a lot of options.
Mounted it near the HVAC, got one in a premade case.
*Another link with the case, I don't work for them, it's what I landed on:
https://www.athom.tech/blank-1/4ch-inching-self-lock-relay-for-esphome
I have an ecobee I mainly control locally through the HomeKit integration on HA. Just about all of the basic features are covered: setpoints, heat/cool/auto/off and fan on/off/auto. Some of the more advanced features like Home/Away/Sleep profiles are not available through the integration, but they tend to be set & forget.
It doesn't need Internet access or the companion app to operate your system, though it will use external access to track local weather and energy rates. (And probably collect usage data.) The companion app gives access to a few more features remotely, but the unit is completely programmable from its front panel.
It's worked out fine for me so far. My local power utility sells them at a steep discount through their online storefront. Check around for rebates.
Just installed the Honeywell T9 yesterday. It integrates with Home assistant offline, and handles my heat pump stages. Pretty happy with it so far.
We're about to be on the market for a new thermostat so this post is just in time. My husband got us a nest and apparently after 10 years they just nope out. Not because it breaks per say but because after 10 years it just shuts down no matter what "expires". Might consider the honeywell
Nest requires the internet and Google cloud connection in order to work. They can just shut it off at any time.
You might be thinking of Google recently announcing that they’re no longer supporting older Nest thermostats. Not because they’re broken or anything, they just decided it was too much work for them so those people who bought a working and still perfectly good thermostat should just go ahead and give them more money.
Because they decided.
Never buy a Google product.
No, but I have a Honeywell T10. It connects via wifi and HA via HomeKit. I also added it to a firewall list blocking it from accessing the internet.
Works great!
I started looking with similar requirements and maybe things have changed over the years but ended up with ecobee as my best choice. I didn’t like that it was a cloud thermostat but it does a lot and just really works well for me. So far no issues related to being a cloud thing.
While I do have it configured in home assistant I have to admit I like their app enough that I usually prefer that
I have an ecobee too (and have for about 8 years), but I thought I heard that new ecobee users couldn't get the access that HA uses.
The HA Ecobee integration requires a developer API key which ecobee no longer distributes, if you already have a key it still works, but they stopped giving out new keys a few years ago.
On the other hand, the HomeKit integration allows new users to control most of the thermostat's features locally over WiFi. I got my thermostat after the Developer program ended, and this is how I control it today. Once you install the HomeKit integration, it will discover the thermostat if its on the same LAN, and then prompt you to add it.
I think Ecobee and Honeywell are the two more popular Zigbee ones. I think all of the major WiFi ones now support matter as well.