Cracks in radiator vent?

The vent (the bell shaped metal knob, not the valve) to the apartment radiator has a long crack in it.

I'm not sure what this means.

Should I immediately turn off the radiator and stop using it, or is it still safe?

Here is an example of what it looks like (not as bad and not the actual vents, but an example I found online)--

2 Answers

  • 3 years ago
    Favorite Answer

    If it is cracked then steam will escape from it when the boiler is running, and will raise the humidity in the room, and cause the water level in the boiler to decrease. However, none of those things are particularly bad. There is no need to turn the radiator off.

    However, it would be a good idea to replace the cracked vent, which you can probably find at your local hardware store.

    The vent is supposed to allow cold air in the pipes and radiator to escape to make room for hot steam that rises from the boiler when it lights up. If the vent was stuck closed, the cold air couldn't be forced out of it by the hot steam, so the cold air would be trapped in the radiator and the steam would never enter it - so the radiator wouldn't get warm.

    If the vent is operating properly, after the rising steam pushes the cold air out of the radiator, steam comes out of the vent for a minute or so and then the vent is supposed to close tight (which it does on its own, as a result of becoming warm). A properly operating vent will not continuously whistle or burble, or emit steam into the room after it warms up and closes. It will stay closed until the boiler shuts down and the steam in the radiator cools and condenses. The vent will then relax to the open position again, ready for the next heating cycle. The condensed steam trickles back down the pipes as water, and refills the boiler's water jacket.

    Boilers for that sort of heating system generally do not have automatic water filling, so if your vents are all worn out and allow the steam from the boiler to escape from the radiators into the rooms, then no water will condense in the radiator as it cools, and trickle back down, and the boiler will lose the water that it was filled with. That means someone will have to go downstairs and refill the boiler every couple days, in a system with lots of radiators. That is a good reason to replace worn out or cracked vents.

    • Christian101
      Lv 5
      3 years agoReport

      Thanks for this very thorough answer.

      I was worried that the thing will like explode and scorching steam will shoot out

  • br549
    Lv 7
    3 years ago

    Here in south Georgia, I never have that problem!

    You need to replace the vents for certain, but they aren't really dangerous. They could become costly, or cause damage it seems, but if you need the heat I would sure use them!

    Read about what they do, and how they work here:

    I also moved your question from the automotive to the home and garden section.

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