I’m not really sure I can explain that very well in english. Our apartment complex works like many others from old times here in Germany: there’s a big thermostat on the main heating unit in the cellar, then every apartment has a radiator in each room except the corridor with a valve. According to my landlords, the bedroom and living room should be connected and the bathroom and kitchen are a separate circuit (anterior and posterior circulation). The pipes for the bedroom should go through the 3-room apartment of my neighbour however, which is the only idea we have why it’s still working 🤷🏻‍♂️