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Big Mouth vent question

adambnycadambnyc Posts: 258Member
@Sailah question about the BMV. I’ve got two of them and they don’t seem to open to allow air back in. Is this by design? After the heating cycle when the steam is retreating, the vents on my rads hiss pretty loud when pulling air back into the system. Should the BMVs open to allow the air back in? Seems to me that if they did, then my rads would hiss a lot less.

Comments

  • BobCBobC Posts: 4,929Member
    I have one on my system and have taken it apart once to see how it's made. I can tel you that vent will open up when the steam stops, it may take a minute or two to cool because of it's mass but it will open.

    What pressure is the system running at?

    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
  • adambnycadambnyc Posts: 258Member
    I have the vaporstat set to cut out at 1.5. Thinking about holding a match up to it after the steam cuts to see if it pulls in air. I’ve stood near them and never hear a sound on vacuum. They are working great to vent.
  • SailahSailah Posts: 785Member
    The thermostatic disc requires about 15 degrees of cooling to crack. Even then the disc is still probably pushing against the o ring. So really it's a question of time to cool the vent.
    Peter Owens
    SteamIQ
  • adambnycadambnyc Posts: 258Member
    Thanks!!! It’s operating as intended then. I’ll replace maid o mist on the hissing rads with a quality vent and see if that makes things better.
  • adambnycadambnyc Posts: 258Member
    Just thinking this one out. Is there another main vent that I could use that would solve this issue? I would just add it to the two BMV to solve for the vacuum.
  • FredFred Posts: 7,733Member
    @adambnyc The Big Mouth opens faster than any of the other main vents I've seen. I know faster than the Gorton #2 or the Hoffman 75.
  • Matt722Matt722 Posts: 14Member
    > @adambnyc said:
    > Just thinking this one out. Is there another main vent that I could use that would solve this issue? I would just add it to the two BMV to solve for the vacuum.

    Did you ever find a solution? I have same problem when heating stops some of my rad vents hiss as they let air in. Not using BM. Have Gorton 2s and 1 on the mains.
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