Best, easiest and of course lowest cost smart thermostat for Home Assistant

Yeah, I want it all like most of us out there… But seriously

I am looking to replace my HAI OmniStat 2 thermostat that has failed. Looking for an easy to integrate thermostat that Home Assistant can control. I do not have any Z-Wave or ZigBee devices. Privacy is paramount so I do not want to use Alexa of Google or anything like that to control it. I really am in a quandary and just want to reach out and see what the Home Assistant community has to say.

Oh and I am very very new to HA…

Thx

What is it controlling?

Would you go zigbee or zwave?

Is it switching 120v or 240v?

Mine still works (FWIW, I wrote a driver for it to work with my home automation system 12+ years ago; it
now works with Home Assistant via MQTT) but I have been investigating potential replacements in the event it fails.

Currently, I lean towards the Honeywell T9 Smart Thermostat, primarily because it works with remote temperature/motion sensors and it’s accessible locally via the homekit_controller integration. However, it doesn’t have some features found on the OmniStat/2 (like humidifier control and multi-stage heating). The next model up, the T10, supports that and more but is meant to be installed by a professional (you can buy the T10 on Amazon but its warranty is voided if a non-professional installs it).

I have a standard single stage furnace. I would consider Z-Wave, from what I have read zigbee is not as easy to deal with. I am not switching 120v but I do have a Oil filled portable heater I use as backup heat (freeze prevention) since my OmniStat will turn the furnace off if I try to adjust the temperature.

You could use a relay + contactor, and esphome. And/or a lanbon l8.

https://haswitchplate.github.io/openHASP-docs/0.6.2/devices/lanbon-l8/

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I was already leaning towards the Honeywell line. My furnace is not currently a zoned system but I have considered potentially working towards it by putting in motorized dampers. I think that HA would be a great fit for that. Any thoughts?

This is very interesting. Can the Lanbon do more that just on off?

Thx

Yep, anything an esp32 can do

I have no practical experience with motorized dampers. What I do know is that you need to ensure they don’t overly impede air-flow (like making a programming mistake in Home Assistant that causes all dampers to close) to ensure you don’t unbalance the HVAC system (i.e. your furnace becoming unable to push the air it draws because too many dampers are closed).

FWIW, the remote sensors I mentioned are a means of improving how the thermostat measures indoor temperature. For example, maybe the thermostat is mounted in great spot to see/access/control it but a lousy spot for measuring your home’s ambient temperature. You can install a remote Smart Room sensor (temperature and motion) in an optimal location and instruct the thermostat to use it for measuring indoor temperature.

Alternately, you can install several Smart Room sensors and instruct the T9 to use the average of them or just the rooms where you are active and motion is detected (because the Smart Room sensors also have motion detection).

Because the thermostat communicates via the HomeKit protocol (over Wi-Fi), Home Assistant is immediately informed of all of the thermostat’s activities including when motion is detected in a given room and the room’s temperature. So if you want to create automations based on presence or room temperature, the Smart Room sensors will provide that for you.

The nice thing is that all of this remote-sensing temperature control works without Home Assistant. In other words, if you want to use Home Assistant to control your HVAC system to a finer degree (such as with dampers) you certainly can but in the event your Home Assistant server is offline, the thermostat still does its job according to how you configured it. This adheres to my personal philosophy of “interconnected but independent islands of home automation”; everything continues to perform the basics (lighting, security, HVAC) even if the home automation server is down.

@Taras explained it well. I’m just posting to add that my experience with Honeywell thermostats has been good. (Not the T9; mine don’t do remote temperature sensors.) It’s important to note that the Honeywell integration to HA is cloud-dependent. I’d have preferred something local, but I’ve come to accept it. The redundancy offers some protection should HA go down while I’m away (as long as the network is still up) and of course I can always change settings at the thermostat if I’m home.

In my climate, I couldn’t trust something as critical as my heating system to HA, much as I’d love to. Also note that HA is abandoning support for GPIO pins on the Raspberry Pi line, so you’d be adding another piece of hardware, another power supply and and another network connection, all of which could fail.

The best part is, there’s nothing to de-install if I ever want to sell my house. The Honeywells will keep on working for the new owners, who can (if they want) set up their own account at Honewell, or just leave them as standalone devices.

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As mentioned, the T9 supports Homekit so it integrates with Home Assistant via the homekit_controller integration. That’s a “Local Push” means of communication, arguably the quickest and most efficient.

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All of you have given me food for thought. I definitely see the merits of redundancy. I currently use a oil filled heater as backup heat incase the furnace stops working. I live in a very cold climate as well. Luckly my house is made from 8 inch SIPs so it is very easy to keep above freezing even with only one 1875 watt heater in a 3800 sq house. The furnace went out when I was in Florida for two weeks and I watched the house drop down to 48 degrees during the last 6 days. Maybe next time I will plan better.

Thanks for all the advice, I appreciate it. I will be posting more questions as I try to get something working.

So I have been looking at a lot of different ways of solving my thermostat problem. One concern I have is privacy. Is Honeywell using Chinese Tuya technology or cloud services? I really like the fact that it can be a stand alone product separate from Home Assistant. Sorry in advance if I offend anyone with this question, I certainly do not mean to.

Thanks,
Dave

If you follow @123 's advice, the answer (as he has said) is no.

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I switched out my thermostat for a GoControl GC-TBZ48 ($100 on amazon) a week ago and it is doing exactly what I want.

That GoControl device looks great. If I were buying today I’d be seriously considering it, thanks for posting!

Can you program the schedule into the thermostat, so it’ll still run the schedule if HA is down?

It looks like it can run off the “C” wire as well as battery. Is that correct?

I have it running off of DC (vs. batteries), yeah. It looks like I could program a schedule in it as well, but haven’t tried. The zwave control doesn’t seem to change the functionality, just means you don’t have to go poke buttons.

Has anyone tried this super low cost centralite? I was thinking of pairing it with some of the M5Stack simple LCD screens around the house.

Have you used the search here? Zigbee thermostat - Centralite Pearl Thermostat

Thanks @nickrout !