Hans_Lree
(DigiH)
3
Cheapest one I can think of is a Bluetooth one, at around €19 a pop
https://www.e-home24.de/heizungssteuerung/smart-heizkoerperthermostat-mit-bluetooth_20528329_1406/?ReferrerID=121
Helped someone else on here a while back to get the same model, different brand name, one hooked up to OH.
I suppose all such “electronic TRVs” will be around this price or more, with conectivity included, so that they can be interfaced with openHAB.
