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Steam coming out of radiator vent

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bwroga
bwroga Member Posts: 44
Hello,
I set our thermostat at 65 during the day and 60 at night. When I turn the thermostat up in the morning on very cold days, the vent on one of my radiators will shoot out steam towards the end of the heating cycle after the whole radiator warms up. I'm assuming I should replace the vent.

It is a Vent Rite adjustable vent. This is the only replacement I could find, but it says it has a 1/8 inch connection. The little tube on my vent that screws into the radiator is more like 3/8 inch in diameter. Is this the wrong replacement, or am I missing something?


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  • Grallert
    Grallert Member Posts: 644
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    Yes the 1/8 is the correct fitting. If I'm not mistaken and I really should know this, The inside diameter of the vent nipple is 1/8.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
    ethicalpaul
  • Jamie Hall
    Jamie Hall Member Posts: 23,303
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    Check the cutoff pressure on your boiler -- it may be high enough at the end of a cycle to overwhelm a less than perfect vent.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • bwroga
    bwroga Member Posts: 44
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    Thank you @Grallert and @Jamie Hall
    The pressuretrol is set to between 0.5 and 1.5
  • bwroga
    bwroga Member Posts: 44
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    The pressure gauge on the boiler stays bottomed out at 0, which I posted about in a new discussion.
  • bwroga
    bwroga Member Posts: 44
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    I know the original post was from a year ago, but I finally replaced the vent ;)

    It seems to work, except the new vent now makes a whistling noise when the system starts up. Does this indicate a faulty vent?

    When the system has been running for awhile some of the radiator vents that have been closed suddenly open and make a loud hissing sound and then after a few seconds close again. Does that indicate any problems, or is that normal?
  • ethicalpaul
    ethicalpaul Member Posts: 5,702
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    Actual "whistling" is usually a sign of too-high pressure or lack of main venting (which forces more air than necessary through the small radiator vents instead of through the large main vents)

    It is normal for vents to open and close during a long heating cycle. Some vents are more noticeable than others. But again if there's loud hissing, that points to too much pressure.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    bwroga
  • SteamingatMohawk
    SteamingatMohawk Member Posts: 1,007
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    The outside diameter of 1/8" pipe is 0.405".
    bwroga