Hi Allesandro I have thought about it for a longer time. But it’s not only about the spread, but also about the amount of water circulated, which results in the provided amount of heat. What’s decisive for the heat emission from the underfloor heating to the room is rather the temperature difference between the floor covering surface and the room temperature. How the temperature of the floor covering surface is achieved is ultimately irrelevant. Or do I have a thinking error there? Otherwise, can you provide sources for the statement to read up on? I’m really interested. Regards
The water has to release energy in the form of heat to heat up a room. And it should happen where it is needed, in this case in the living room. If you naturally have many heating circuits running through the hallway, each with supply and return flow and a very small spread, all pipes are approximately equally warm. Even if you now shut off the hallway, it hardly has any effect. With a spread of 5K, although 3 supply pipes are warm, the 3 return pipes are "cold", which lowers the "average temperature" and does not heat up the hallway as much.