Room thermostat rotates by itself

Hello,
I noticed this morning that the room thermostat in the stairwell had turned itself up to 30 degrees as if by a ghost.
And I have no idea why.
The heat pump is currently set to hot water operation only. Heating/cooling operation is turned off. It is a Daikin Altherma 3 R Ech2o and underfloor heating.
Is that possible or do I need to hire a ghost hunter?

What kind of heating it is does not matter at first. It would be important to know what kind of room thermostat you have there.

Could that be possible or do I need to hire a ghost hunter?

Children in the house? They’re not ghosts, but sometimes little monsters.

Children in the house? They’re not ghosts, but sometimes little monsters.

I saw it myself how the ERR turns, because it didn’t happen completely silently.

What kind of heating system it is does not matter at first. It would be important to know what kind of room thermostat you have there.

Maybe you can make use of the picture.

I don't know the brand directly, but it looks like the cheap regulators from Prineto. I once had them in an apartment and dismantled them myself to install smart thermostats. I can show you a photo from the inside:



The round regulator is plugged into the red socket. As you can see, there is no motor or anything similar installed here. So it shouldn't be able to adjust itself. Anyway, the whole thing runs without power, as it is just a simple thermostat. How it could adjust itself in your case, I don't know offhand either, but maybe the manufacturer can tell you something about it.