Thanks for explaining! This confirms what I observed.
But the problem for me is that the 'slightly heating' of the rooms with no heating need is at least 1 degree. that is a lot (I think) and enough for my wife to complain.
If I don't fix this I will be banned and spent the nights in the chicken coop and it's cold out there!!
What I don't understand is this: the system 'knows' the boiler is heating up and the living room is already 0.5C over the set-point. Radiator valve is still somewhat OPEN
WHY would the system not close the living room valve...?
But if that is normal behaviour than I have to return to the old situation.