After a while, many buildings were retrofitted with thermostats. I know from experience that in Eastern Europe until the late 90s, there were valves but no thermostats, and radiators were effectively serially connected, so if you shut a valve, everything downstream was shut off too. Some units were always hot and people were growing tropical plants and had their windows open the whole heating season. Other units were miserably cold, depending on where they were within the building.
After a while, many buildings were retrofitted with thermostats. I know from experience that in Eastern Europe until the late 90s, there were valves but no thermostats, and radiators were effectively serially connected, so if you shut a valve, everything downstream was shut off too. Some units were always hot and people were growing tropical plants and had their windows open the whole heating season. Other units were miserably cold, depending on where they were within the building.
Fair enough, bimetal thermostats on parallel lines were standard in at least the 60’s here.