Is the Vitodens 200-W sufficient for underfloor heating?

Your supply temperature should be sufficient if your flow rate were correct…

Not even 5 m³/h are displayed.

Please be careful, 1 m³ of water = 1000L. The two-digit values I mentioned were in L/minute.

Turn the flow meters up a bit so that the flow rate increases.

The flow temperature is certainly high enough. Even on the higher side for underfloor heating. In new buildings, it often runs below 30°C at subzero temperatures... Another possibility is that there is air in the system. Then you cannot transfer any or as much power.

Oh dear, when I already read about individual room control here, it makes my neck hairs stand on end. Then a flow temperature of 47 degrees at 0 degrees outside temperature? Totally off. The difference from 7 to 10 degrees outside temperature can also be explained by the heat radiation of the exterior wall. Was a thermal balancing already mentioned?

Is not a heat pump. It is also possible to work sensibly here with individual room control… Depending on the size of the house, the supply air temperature must also be higher. The problem here is probably with the flow rate.