Danfoss underfloor heating too warm

or the ERR is disabled! (as is quite often recommended here in the forum)

That would also be a possibility, how do I find out if it is disabled?

So after having 26 degrees room temperature in the living room today and the control on the room thermostat making no difference, I have slightly reduced the pump performance. What else could I try? Could I reduce the flow temperature to 25 degrees as the next step? Somehow I have to get the apartment cooler :confused:

So I can’t make sense of the picture. The longer I look at it, the more confused I get. The combination of pump, plate heat exchanger, the wiring and piping, cold water meter (but no heat meter), etc. makes no sense to me. There is a controller set to 30° (flow temperature?) on the same line there seems to be a solenoid valve (or similar) doing something. Also the controller in the middle set to III? What does it do? To me it looks like a “normal” radiator thermostat valve. But what for in this configuration? There is also something similar above (thermostat with the tube coming out marked with + and - …)

Also the symbols/labels below with warm and cold feet etc.?

I’m afraid you need to ask a professional, preferably the one who installed the thing.

Or: You document every setting (take photos and mark with a fine liner pen?), and turn off all the controllers completely! Then gradually turn them back up in small increments. But keep in mind that underfloor heating is very slow and changes may take 2-3 hours to take effect!

So the first picture you posted is the supply line for the underfloor heating and the water. In the 2nd picture is the heating circuit distributor, but I don’t see any actuators there.
Theoretically, I would now turn down the temperature on the right regulator from picture 1 until it slowly gets cold in the apartment. And then adjust at the room controller if a room is still too warm.

Otherwise, ask the janitor if you have one.

Wäre auch eine Möglichkeit, wie finde ich heraus ob diese deaktiviert ist?

Turn the regulator and see if anything moves in the distributor.