Rattling radiator valve vs. air vent

Jim Bennett

valves are still available.

http://www.gorton-valves.com/

Inwood Steam

Rattling radiator valve vs. air vent

In my 1930's house basement there are three vents on the single-pipe steam mains. A small pipe near the boiler has a 1/8" radiator air valve for a vent, which I replaced, while another main has a more serious-looking 1/2" straight air valve or vent, which I left as it seemst to work and is rusted into place in any case. The problem is with the third vent, which is a 1/4" stem that comes off a bend in the biggest main. The previous owners reduced this 1/4" stem to an 1/8" dia with a threaded insert and stuck a straight radiator air valve on it. I replaced this air valve as it had long been painted over. I used a simple cheap cylindrical valve, the only straight valve that I can find at area hardware stores and Home Depots. However, the new valve began rattling when the heat was really firing, and I think it was the float in the valve that was making the racket. The pressure is pretty low (.5 to 1.5 psi), so I don't know why the valve was getting beat up but perhaps the problem is using a radiator valve for an air vent in the first place. Should I be using a dedicated air vent/eliminator here instead? Do they even come in 1/4" dia? Or should I just keep trying other 1/8" radiator straight air valves until I find one that doesn't rattle? Why is this rattling in the first place? There is nothing otherwise wrong with the valve. Any suggestions?

(Additional background - In general, I replaced all the other ancient air valves with Maid O Mists of various sizes, and those have worked great. The exception was an old Gorton, which still works wonderfully. Wish I could find more of those)