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Main vent hissing when boiler is firing

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Oz
Oz Member Posts: 8
in Strictly Steam
Is it normal for a main vent to hiss vigorously when the boiler cycles on? I recently had a main vent installed and, since then, I've noticed this hissing.

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  • BobC
    BobC Member Posts: 5,478
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    Pressure?

    What pressure is the boiler operating at, it should be below 2 PSI. That vent is probably too small how long is the steam main and what diameter (or circumference) is the steam main?



    The mains should all be pitched so any water can find its way back to the boiler return.



    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Paul_11
    Paul_11 Member Posts: 210
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    If you can hear the air venting...

    If you can hear the air venting you don't have enough vents.



    If it is steam venting, you have a broken vent



    Paul
    Since 1990, I have made steam systems quiet, comfortable, and efficient. We provide comfort while saving the planet.
    NYC RETROFIT ACCELERATOR QUALIFIED SERVICE PROVIDER

    A REAL GOOD PLUMBER, INC
    NYC LMP: 1307
    O:212-505-1837
    M:917-939-0593
  • Paul_11
    Paul_11 Member Posts: 210
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    In the future

    I noticed that you cut the overhead pipe and installed a tee to install that vent.

    It is much easier to drill and tap the overhead.

    Try it the next time.



    Paul
    Since 1990, I have made steam systems quiet, comfortable, and efficient. We provide comfort while saving the planet.
    NYC RETROFIT ACCELERATOR QUALIFIED SERVICE PROVIDER

    A REAL GOOD PLUMBER, INC
    NYC LMP: 1307
    O:212-505-1837
    M:917-939-0593
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
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    New vent

    I don't know how long your pipes are, but surely you need a vent, or vents with floats to stop the water spewing out.Start with at least 1gorton 2, and watch the pressure during the steam escape phase. When the pressure is below 2 ounces, you know you have enough. Crank the pressure down, until the new vents are silent.--NBC
  • Oz
    Oz Member Posts: 8
    edited January 2013
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    Pressuretrol set to

    Cut-out 1-1/2 psi

    Differential 1/2 psi

    Looks like water level in gauge glass has also decreased since new main vent was installed and the vent hisses continuously until boiler cycles off, all of which make me think vent is spewing steam, not just air. Calling steam guy who did the work tomorrow.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
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    Verifying the pressure

    If the pigtail under the pressuretrol is plugged with debris, then the pressure can rise and not trip the control, so an accurate gauge, marked in ounces can verify that the pressure is matching the settings.--NBC
  • JStar
    JStar Member Posts: 2,752
    edited January 2013
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    Vent

    That vent doesn't look brand new anyway. Was it just moved? It sounds like it IS failed open.
This discussion has been closed.

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