> The correct approach to variable heat is an adjustable exit air valve. I always wondered why the radiators in some buildings had two apparent temperature con

> The correct approach to variable heat is an adjustable exit air valve. I always wondered why the radiators in some buildings had two apparent temperature controls, one at the bottom of one side (generally a big gate valve) and another at the top of the other side (which I presume is the "exit air valve"). As a student, nobody ever told us how to actually regulate the heat, so there was a lot of randomly opening and closing valves until the thing either got hot or cooled down as needed. Or, more commonly, you just ran the thing full blast all the time and opened a window when it got too hot, titrating the cold air from outside against the overwhelming heat from the radiator. A couple of laminated instructions stapled to the wall near each radiator probably would have made the system perform much better.