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Radiator Air Vent replacement?

I live in a pretty old nyc apt building with about 30-40 apts built in the 1930's I believe. The radiator I have in my room works perfectly although it does get pretty hot, it works fine nonetheless expect the air vent itself has an continuous loud hissing sound anytime the heat is on. I wanted to replace the Hoffman no.40 with another vent. On amazon I seen vents like the varivalve and Hoffman #1a that can be adjusted. Just wondering if its possible to get those kinds of vents or should I just get a replacement Hoffman no 40.


  • Jamie Hall
    Jamie Hall Member Posts: 23,273
    If you are satisfied with the heat in your apartment, I would replace like for like.


    That may not stop the hiss, which is more likely not a problem with the vent but with the whole building operating at too high a pressure, which you can't help.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Nick12599
    Nick12599 Member Posts: 2
    Thanks for the info.
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    edited December 2020
    Once it's hot it doesn't really need to vent anymore. You can rotate the vent upside down and it may seal better. Or if you are really adventurous you can pipe a 1/8" NPT valve in before the vent and close it when you are trying to sleep.

    These parts will help:
    street elbow

    Don't break the radiator!
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • neilc
    neilc Member Posts: 2,702
    what would happen if you loosely wrap the vent with say a cotton rag ?
    kinda make a muffler wrap where the vent hole is,
    it's still gonna breathe thru the cotton,
    and may deaden the hiss some,
    anything wrong with this idea ?
    (asking the pros here)
    known to beat dead horses
  • dabrakeman
    dabrakeman Member Posts: 552
    ... or just get an adjustable vent.
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    An adjustable vent may also get overwhelmed by the suspected high pressure 
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • dabrakeman
    dabrakeman Member Posts: 552
    Yes the hissing is most likely either due to too much system pressure (likely from not enough main venting) or the radiator is just venting too fast. An adjustable would allow ability to play with the vent rate to see if slower venting could reduce the rate the air is being driven out of that radiator and thus reduce the hiss.  Balance with getting enough heat.  Suggest a VentRite adjustable. 
  • mikespipe
    mikespipe Member Posts: 36
    the Hoffman 40 is a good slow venting valve. increasing the vent speed will not help you as your heat is adequate you might check with the building super as to what pressure the system is operating at . you can refer him to this site if its anything more than 1psi