Should air vents be opening and closing frequently?

OccamsShaver

Single pipe steam system.... adjustable steel vents on radiators. I hear the air rush out, click - vent closes, and this repeats within a matter of minutes. The main radiator I notice this on is just above the boiler.
I am waiting for a local steam expert (from this board) to come check and maintain my system, but I am very curious about this.
Thanks

Dan_NJ

Are you sure the click you're hearing isn't the opening of the vent and a rush of air breaking the vacuum after a heating cycle is complete? I had one specific Hoffman 1A vent was quite loud when it did this. It did so after almost every cycle until I made some vent changes.

I've also had them click open for a moment or two during a cycle and close again, they would make a hiss then when steam escaped but only for a few seconds and would stay closed most of the cycle after a few rounds of that open/closed business early in the cycle.