Implementing a smart thermostat


I asked the below question yesterday on Discord and the answer I received was:

one of the moderators last week said he would never run a heat system on a HA based system

In addition for looking still for help, can some one tell if there is any reason for that?
Thanks for your help.

Here is my question:

I’m looking for a solution to my heating system. I searched the forum and google and only found components that work with existing thermostats while I’m looking to implement my own.

I have the following setup at home:
1 boiler with on/off switch
1 z-wave switch that can turn on/off the boiler
8 Popp thermostatic valves
8 temperature sensors in the zones where are the 8 Popp thermostats.

For each zone, I’d like to have a climate component which can consider the target temperature and the current one provided by the temperature sensor. But I’m looking for something smarter than “turn off the switch if the temperature room is greater than the target temperature and turn it on if it’s below”. What I’m looking for should take into consideration some characteristics of the room, of the radiator (e.g. inertia), and of the outside temperature.

Note that before using HA, I was using Domoticz and a plugin named SVT (for smart virtual thermostat) implements this algorithm.

Regarding the wisdom of running a heating system with home assistant, one big factor is if you live in a place where it gets below 0C regularly. If it doesn’t, then in general the worst case for your heat shutting down would be a nuisance. I’d think most people wouldn’t have too many hesitations about that.

There was an excellent thread on this topic recently:

I understand and it makes sense.
So if I understand well, there is no smart thermostat for HA.
I’ll look around again for a couple of weeks while starting with HA then I’ll try to implement mine. I’ll come back here to share if I have anything new and working.

If you use a thermostat and not a simple switch, I mean that it has its own schedule and/or a temperature to switch on/off, I don’t see a problem.
I have a cheap wifi thermostat. Alone, it works with its own schedule, but I didn’t set any. This could be another safety.
Through HA, I set the temperature to 12° when I turn it off, and to 25° when I turn it on. Should HA disappear leaving the thermostat in any state (off or heating), it wont let the temperature go too low or too high.

Simular to above, I wired a set of relays (one per zone) in parallel the the existing, non wifi thermostats that were in our house when we bought them. The old thermosts are set to 50F. I use HA to trigger another raspberry pi that controls these relays to enable wifi access and smarts to my heater. Now if the network or rpis went down, I have the old thermosts still there to prevent the heat not turning on in the winter.


i am just arriving and discovering home Assistant trying to see if there are advantages to use this software instead of Domoticz I use now in general and particularly for heating regulation.
In domoticz i use constantly and for a while SVT plugin (smart virtual thermostat)
4 shellys on/off for actuators (tts electrics radiators)
2 zones
3 thermometers (zone1, zone2, outside)
I had to modify my radiators : they were pilotewired 4 orders with a delta dore scheduler.
to avoid overheating in case of domoticz stop (bug or other reason) i use the order “economy” because this order needs 220V to be active.
the temperatures are supplied by 433 Mhz thermometers
The SMV thermostat is very accurate and very stable.
So i don’t understand the reasons why HA won’t be a good base for a heat system.
This explains perhaps why my quick searches for finding something equivalent in the blueprint stay
but this post has been released 3 years ago perhaps the tendencies have change? :wink:
thank you for reading…

Like yourself I changed to HA from Domoticz and ended up making my own solution for multi-zone heating system, the same way as I did in Domoticz. This is the first season now and I admit not all goes smooth, but I like HA way much more than Domoticz.
Initially I looked at some examples other people made, but none was good enough for me. In short, using Node-Red as a HA plugin gives much more freedom and the opportunity to make a dashboard as good as you like.
My system is a bit more complicated compared to yours, as it is pellet boiler based and has hot water valves for 3 heating zones. I use same kind of 433MHz thermo/humidity sensors distributed over a large area. The main comment here – those wireless sensors are not reliable enough when thinking about something more than just show some area temp, but be used as a zone temp reference for the heating system. I tried to use two sensors per zone and looked at readings timestamps in case some sensor fails. The obvious inconvenience is changing of sensor ID on battery change. Some manual tweaking is required every time.
As a conclusion, HA is very good for any kind of automation, including multi-zone heating but it depends on your skills when you are building it from scratch. Provided you may have some special kind of components to be automated it is every time a challenge.

My system has evolved a little bit since my original post. I’m in the process of changing my z-wave valves in Zigbee valves, much more reliable. The rest of my system did not change. Still a virtual thermostat by room, set with a virtual switch and an Aqara temperature sensor. The virtual switch sets the temperature of the Zigbee valve to 15 if it’s set to off, and to 28 if set to on.
I’m using mainly this smart thermostat.
I added some sensors and alerts, for when a virtual switch and its corresponding valve do not have the same state, for when a temperature sensor’s value does not change for more than an hour, etc. Things to be alerted when something goes wrong.