Well. At least the first heating circuit in my house. It is now controlled via homematic. And because I have an in-floor heating system, it wasn’t that simple. Here’s how it works:
But since I want to control everything from openHAB, I coupled my openHAB installation with the CCU and configured basic parameters to be configurable via openHAB. This solutions works great so far and has the beauty that openHAB only controls the relevant parameters while the complex (and mostly not needed) items are only cluttering the CCU interface.
Since some people raised concerns regarding the control of a slow in-floor heating system via homematic, I did not switched on the control from day one. Instead, I used OpenHAB to monitor the temperature of the room by still having the original control in place. The idea is to gather comparable data in order to find out whether homematic does a good job here. So far, everything works as expected.