Thermostatic Radiator Valves/Adjustable Vents
Have a one-pipe steam system. Two rooms get warmer than I'd like - one the finished attic to which all the house's heat naturally rises, and an upstairs room with a treadmill next to a radiator. I've seen This Old House segments showing thermostatic radiator valves that seemed like a good fix. My plumber, though, says that I have adjustable air vents (Varivalves) which should allow me to limit heat just by closing them. He also says thermostatic valves cost hundreds of dollars, which they don't.
Anyone else have experience with adjustable radiator air vents? Do they work for you? Anyone have experience with thermostatic radiator valves? Do they work?