I have not been able to find an intelligent thermostat for my radiant floor. This heating system dates back from 1957 with copper tubulure that is feeded with a water boiler. There are only two wires that could be connected to the thermostat.
I have tried the avatto type A from aliexpress which work fine for the modern water floor heating of another home. But it does not work for my heating system.
I imagine that two variables are important, voltage and amperage to find out which intelligent thermostat will work. But what else?
Humm here’s an alternative:
If you can find the protocol to control the boiler; you can turn it on and off. That should be simple enough if you have the original ones.
Use an esp8266 to turn the boiler on and off.
Then use those thermostats you found, not to turn the boiler on, but to turn on the rule that will send the command to the esp8266 that will send the command to turn on the boiler.
and that’s exactly what I suggest. You have one boiler, and the boiler must be ON. Regardless if you have one zone or 5.
Instead of finding a compatible thermostat with the boiler, you have the boiler and use a modern valve in the zone.
Your current thermostats just close or open a circuit, the only issue I see is sending power to an intelligent thermostat so that it can use WiFi otherwise it’s the same as the Emerson programmable thermostat you showed in the picture.
When you say the avatto did not work, how is it that it did not work?
The unit you are showing in the picture is expecting 110 V, that looks like one of those thermostats used for electric baseboards or electric radiant floors.
The thermostats you are currently using, the Honeywell and the Emerson are closing a low voltage circuit, my furnace uses 24V but your boiler might be slightly different, I am not an HVAC person.
I think you need a regular smart thermostat something like a Google Nest for each one of your zones. I think there are some Google nests that run on batteries although I don’t know how long they last.
