I have 13 of these units, and I am quite happy with these. Except for those of my units where there is no physical floor-temperature sensor available, they work just as they should. When you don’t have an external temperature sensor, the internal sensor is used, which suffers from internal heating in the unit, just as stated in the manual (there is firmware code in the unit trying to do the best out of the situation).
It is possible to obtain the state currently-heating-or-not using a hack on the logfiles, after associating group 2 to your OpenHAB controller.
Hopefully, this will be included in the database/binding at some point, see the thread: