That is nicely warm, so lower the heating curve!
Important, what are the other room temperatures and the flow rates now?
You need them now to balance the heating circuits with each other.
Please set them and then we continue. What is the current heating curve? Total flow rate?
Be patient. We don’t know your underfloor heating yet due to the lack of documentation. But it will work out.
But it's only 2.5 degrees between the hallway and living area, maybe that is achievable. About 19.5 hallway and 22.0 living would be greatWhat I noticed is that I don't believe you can achieve the 4° temperature difference between the hallway and living room/kitchen. It might depend on the floor plan and habits, but presumably the air exchange between the rooms is too great.
I have to intervene here. Isn't it actually exactly the opposite? With the small area, where presumably the shower is also excluded, you have to heat the entire room. Now you also turn down the flow. That means on average you have a lower temperature. With that, you probably won't get the room to a comfortable temperature and have to raise the temperature curve. Now the other rooms become too warm again and you turn down the flow there. Result: different return temperatures again.
Do you have a temperature sensor on every return line? Otherwise the water in the HKV would mix anyway.
For me, the rooms where it should be warmest (bathrooms and living room) are turned up fully.
It probably also depends on the heating system. In my system, the return temperature doesn't matter at all. My heating is only controlled by the supply.
Hard to tell from the photo since it’s taken at a bit of an angle, but it looks more like >2.5. My floats look a bit different, I would go by the red "plate"...Please take a quick look at the attached picture, how much volume is that? 2?