Hey maybe Velbus is something for you. Ask @MDAR for more information.
I for my part will use https://www.moehlenhoff.de/oem-alpha-2-system
Here is the manual https://www.ezr-home.de/index.php?option=com_content&view=article&id=4&Itemid=10&lang=en
- it has virtual Thermostats where you can use external Roomtempratures from Openhab
- with virtual thermostats if Openhab dies and the station gets no new temperatures for the Room it changes to emergency operation.
- you can change the setpoint at the thermostat and in Openhab
- Pump connection
- Boiler connection
- OEM of Homatic ip
Greetings Markus