I just noticed that the central heating boiler in our flat supports the #opentherm protocol, and that there are controller devices for it which communicate with electronic radiator valves and temperature sensors to control not just on/off state but heating and tap water temperatures ... not cheap but might save us a lot of gas. but it's hard to finnd the options that make sense for us.
Does anyone know a site that has a decent overview, or experience with one of the "smart" openTherm setups?
important for me:
* at least 4 (better more) heating zones
* ability to manually set temperature at the radiators
* the device should regulate heating water temperature (tap water optional)
* no data leaving the LAN
* no risk of the system becoming useless because the vendor dies or something (i.e.: web interface is better than proprietary app to control the system)
* (not sure if possible:) ability to mix devices from different vendors (e.g. replace/add radiator valves some years later)