@joriskofman Thanks for idea. I have already considered this, but my experience is not very positive. We used these wax valves previously for complete analog control, they have been used as bypass valves when water gets too hot. they usually worked great but once in cca 3 years they got stuck. Also the expansion range changes with time. As it has no feedback channel (which is understandable in analogue world, but not in digital world) you discover the stuck wax only when your radiator freezes or boils (depending on type) both usually involves significant damage.
However to be positive I like the quiet operation, very good behavior on power loss and minimum of parts. Currently I’m using them in blinds control, it is absolutely slow, smooth, silent movement end to end cca 3 min.
Usually also the outside part moves so I was thinking of using industrial limit switch to detect max open, but on some radiators the valve is quite exposed and with the limit switch it gets too bulky and fragile.