Sorry for a question that will seem very basic to many...
I have one-pipe steam heating system. Should a radiator air vent ever let out very hot air (or steam)? It happens like this: shortly after the boiler starts, air vent lets some air out, radiator gets warm, air vent closes. If the boiler keeps working for a longer time (~30 minutes) and the radiator gets really hot all the way, the air vent seems to open again and starts letting out very hot air until the boiler shuts off. Is the air vent malfunctioning?
Thank you