I currently have a Nest Thermostat controlling the heating but I am looking at moving over to some sort of TRV setup and controlling the boiler via HA.
The call for heat is just a no voltage switch which in theory should be simple to replace but I cannot find a Zigbee product that does the job. I have seen that lots of door sensors can be hacked to do the job but ideally I would want this to be mains powered to give a little more resilience and keep the heating working.
Everything I have seen is either wifi, live contacts, involve soldering PCBS or one had £50 shipping to UK for a £20 switch…
Failing that is there a way I can get the Nest Link to do the triggering via Zigbee (wasn’t sure whether I could add a switch into the currently unused thermostat wiring but I think that is 12V so I guess that is still an issue)