Thermostat switched off but radioator is warm and keeps heating
I have 4 smart thermostats installed. Last week, even though all smart thermostats were OFF, the radioator in the living room was warm and we could notice the room temperature as higher than expected.
I did the reset procedure, expecting it to be a calibration issue. It did not help. I then switched that thermostat with another spare one (brand new) which went through the initial calibration and all seemed fine, until the next day. After turning it ON manually, and then OFF, the radiator kept heating until today.
I don't know if it's related but all of the graphs for all the thermostats show a flat line today.
Any advise is appreciated.