Yes, I use the Fritz!Dect 301 for our underfloor heating system, integrated into a Fritz!Dect 440 sensor and connected to the Fritz!Box 7490 router. Everything works. Just bear in mind that the floor heating system reacts sluggishly and with a delay of up to a few hours.

I am not a heating expert, but the control of radiators goes via a small metal pin, which is mechanically controlled by the FritzDect 301. Underfloor heating has a different operating principle, so the FritzDect 301 could neither be fixed correctly nor intervene in the control of the underfloor heating. Other systems than the Fritz models would be suitable.