I personally use Homey as a thermostat in combination with z-wave valves on my radiators. But if I would buy a ‘regular’ smart thermostat, I would 100% certain go for Plugwise Adam. My main reason for this is, is that it isn’t dependend on your internet connection or cloud services - Those are optional.
(so, you can use the app in your house if your internet is down or a cloud service has a disruption. Also, suppose something happens to the vendor, your equipment will keep working)
Edit: A nice example of stopping Cloud Services: Nest + Homey = Dead API by 31th August
(regardless of the fact that it currently still works. You are completely dependend on the vendor and if it stops supporting/goes bankrupcy, you’re screwed)
