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Big Mouth vent not closing

Dave_61
Dave_61 Member Posts: 300
We are losing about ½-¾” of water in our sight glass per week. I went around and checked radiators etc and didn’t find anything major. Today, I went down to the basement with boiler running and found one of our 3 big mouths making noise. Two are completely closed but one is definitely making noise, and it’s damp inside the opening. The main is hot. Is there anything to do besides replace it as they’re expensive. It’s probably 3 years old. Thanks 

Comments

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,108
    Call them. They'll help you out.
  • ethicalpaul
    ethicalpaul Member Posts: 4,232
    Yeah this is a known fail point I guess especially among the early ones. I took mine out of service, anyone want it, cut you a deal
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,564
    I had many leakers. Some of the early ones, some of the mid generations, some of the later ones. Leak rate was way too high so I stopped using them.
    ethicalpaul
  • gfrbrookline
    gfrbrookline Member Posts: 723
    I have six on my system, three on each main. One stopped closing about five years ago, they replaced it no questions asked. I haven't had an issue since it was replaced. Still love the venting capacity of these things, much better that a tree of 6 Gortons on each main.
    CLamb
  • Mad Dog_2
    Mad Dog_2 Member Posts: 3,942
    edited January 19
    I had good success with them - no leaders but thats been about 3 years.  You could always get replacement capsules and easilt change them. This Old House is ready for some replacements for the Gorton #2 batteries after 22 years. Ill test drive the Big Mouth vents and let you'll know.  The one thing I suggest is directing any spitting condensate downward with a nipple & elbow facing down so you don't get sprayed with scalding condensate.   Mad 🐕 Dog
  • Neild5
    Neild5 Member Posts: 137
    I have 8 Big Mouths on our system,  3 started leaking not long after I got them, they were some of the early units.  I opened them up and the o-ring seal had failed, it looked like the rubber had melted.  I replaced the o-rings with hi-temp o-rings and have not had anymore leaks.
  • Jamie Hall
    Jamie Hall Member Posts: 20,524
    One thing to remember about Big Mouths -- they are not intended to close against water at all, unlike most other vents. They are temperature sensitive only -- so if there is any water in the area, they can and will spit or even burp...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Waher
    Waher Member Posts: 100
    It might have been @New England SteamWorks , but some pro on the forum stated that when they used Big Mouths in lieu of Gorton No.5 vents they were mounting them ~12"+ above mains to help avoid issues with water being ejected.
  • JUGHNE
    JUGHNE Member Posts: 10,331


    These Big Mouths were added on an unused steam drop from an express down feed attic riser, near the EOM.
    The idea was that the "dry " returns had become wet and would not vent the main.

    Usually you would not put air vents in a classroom, but there was no way to the attic.

    After a few years of use the wall paint suffered a little, (building to be demoed soon).

    Even with this much riser there was still a little spitting.
    The ball valve was added in line in the event the vent really passed water.

    I did this in two other places in the building with similar results.
    But the system worked much better with the vents.
    Long Beach EdWaher
  • Dave_61
    Dave_61 Member Posts: 300
    This wasn’t ejecting water. It was just hissing constantly. This vent was on a loop off the boiler (like an elongated U on its side). The supply is 2” and it loops to a 1” steel pipe that returns to the boiler. The Big Mouth is mounted about a foot above 1”:pipe. Each leg of the loop is about 20-25 feet long. .I replaced the Big Mouth with a #1 Maid o’Mist. Is that sufficient for the loop in question or would I be better off with a bigger vent? By the way, no more hissing and water level on boiler is now stable. Thanks
  • bmma
    bmma Member Posts: 28
    I had a similar problem with the Big Mouth. The company was great to deal with, they were very responsive and willing to help me out any way they could but after my third failing vent, I switched to Gorton #2s.
  • Dave_61
    Dave_61 Member Posts: 300
    bmma said:

    I had a similar problem with the Big Mouth. The company was great to deal with, they were very responsive and willing to help me out any way they could but after my third failing vent, I switched to Gorton #2s.

    I'll give them a call. Right now, in order to decrease my steam loss, I replaced the Big Mouth with a Maid O Mist #1. Based on the steam loop in my above entry, is it adequate for now? I see at 3 oz pressure, the Big Mouth vents 3.6 CFM. What is the venting capacity of the MOM vent? Thanks
  • ethicalpaul
    ethicalpaul Member Posts: 4,232
    The venting capacity charts are imperfect. What really matters is if the vent is venting fast enough for your particular main in most situations

    Since you are handy enough to remove and replace vents, just do this easy test:

    Interrupt your boiler in the middle of a call for heat. Leave it off for some minutes. Power it back on and time how long it takes for steam to close your main vent (in your case, the currently-installed #1). If it doesn't take very long, you are fine. If you want, you can do the same test with no vent at all installed to compare times. I think you'll find the times aren't that different.

    One thing to remember is, as a main cools (even an insulated one), on the next call for heat, the steam will move slower on startup the cooler the main is, because the steam is getting "used up" by re-heating the main to about 212F.

    This means even a single #1 vent can really do an outstanding job of letting all the air out as the steam re-heats the main, even if its capacity seems not large enough according to some chart.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
    Long Beach Ed
  • Dave_61
    Dave_61 Member Posts: 300
    edited January 23

    The venting capacity charts are imperfect. What really matters is if the vent is venting fast enough for your particular main in most situations

    Since you are handy enough to remove and replace vents, just do this easy test:

    Interrupt your boiler in the middle of a call for heat. Leave it off for some minutes. Power it back on and time how long it takes for steam to close your main vent (in your case, the currently-installed #1). If it doesn't take very long, you are fine. If you want, you can do the same test with no vent at all installed to compare times. I think you'll find the times aren't that different.

    One thing to remember is, as a main cools (even an insulated one), on the next call for heat, the steam will move slower on startup the cooler the main is, because the steam is getting "used up" by re-heating the main to about 212F.

    This means even a single #1 vent can really do an outstanding job of letting all the air out as the steam re-heats the main, even if its capacity seems not large enough according to some chart.

    Thanks Paul. Looks like I have a little experimenting to do! I haven't noticed any significant difference in the balance of the heat in the house with the new #1 installed. This loop in question supplies a wing of the house. The wing has been as warm as the rest of the house and seems to heat at the same rate even since I replaced the BM with the MOM
    ethicalpaul
  • Dave_61
    Dave_61 Member Posts: 300
    One further question. We are going away for a couple weeks and I wanted to top off our water level so we don’t have any issues with the super cold weather. 
    Our boiler is a Weil McLain SGO5. I pushed the button on the VXT feeder and added about an inch of water to the sight glass. It took 20 seconds. What would we be talking about in volume? A gallon or so? The feeder has not had to add any water in several weeks but our level had dropped about ½” with heat on. Thanks 
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,108
    edited January 29
    The VXT's are generally set up to feed at 1 gallon per minute. Fifteen seconds would feed about a quart.
    The SGO-5 steam boiler contains 14.2 gallons of water, to the water line.

    Here's the VXT installation instructions:
    https://hydrolevel.com/wp-content/uploads/2021/06/VXT-24-Instructions-web-0321.pdf
  • Dave_61
    Dave_61 Member Posts: 300

    The VXT's are generally set up to feed at 1 gallon per minute. Fifteen seconds would feed about a quart.
    The SGO-5 steam boiler contains 14.2 gallons of water, to the water line.

    Here's the VXT installation instructions:
    https://hydrolevel.com/wp-content/uploads/2021/06/VXT-24-Instructions-web-0321.pdf

    Thanks Ed. Is the water line you refer to the line stamped on the boiler jacket? The distance between that stamped line and where my LWCO probe is is only about 1.5”. You’d think the probe would be placed lower than that.
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,108
    The standing water line on your boiler is 26-7/8" off the floor pad, which is where it should be stamped. They don't specify a minimum line or operating range, though the minimum is usually at the bottom of the sight glass. You may wish to call them to confirm the range. The tapping for the low water cutoff appears to be quite high. That's their design, which seems to give you a 3" operating range, which is not unheard of.

    A loss of 1/2" of water weekly is not unreasonable, but you may want to check your system for steam leaks at the radiator valve stems and sight glass washers. You may be able to tighten it up.

    Checking and adjusting the water line weekly in a residential steam system is normal and expected during heating season.


  • ethicalpaul
    ethicalpaul Member Posts: 4,232
    edited January 31
    I think a loss of 1/2" per week is unreasonable.

    As for how much water it is, what I did was stick a length of masking tape next to my gauge glass, then I drained the boiler to near the bottom of the glass, then I added 1 quart of water at a time and marked the level after each one. My skim port is set up with a permanently installed valve so I can add water or chemicals easily at will.

    Now my boiler is very small and 1 quart of water raised the water level about 1/4" on the glass.

    If you have a large boiler you might add a gallon or 1/2 gallon at a time in order to be able to measure the difference on the glass.

    I don't believe in auto-feeders. Steam homeowners should be looking at their boiler once a week during the heating season to be familiar with how much water it is using and adding makeup water manually.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • Gsmith
    Gsmith Member Posts: 420
    I completely agree re the auto feeder and weekly checking. We don’t expect our refrigerators to automatically refill themselves with food, or our cars with fuel. But, I admit it’s a little problem if you live in a cold climate and travel away from home for any appreciable time in the winter.
  • ethicalpaul
    ethicalpaul Member Posts: 4,232
    Is "a couple weeks" appreciable? If it's more someone should be checking on it (or a wifi thermometer)
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • Ironman
    Ironman Member Posts: 7,088
    “Big Mouth not Closing”

    At first, I thought this post was about The View.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Long Beach EdJUGHNEWaherCLamb
  • mattmia2
    mattmia2 Member Posts: 7,216

    As for how much water it is, what I did was stick a length of masking tape next to my gauge glass, then I drained the boiler to near the bottom of the glass, then I added 1 quart of water at a time and marked the level after each one. My skim port is set up with a permanently installed valve so I can add water or chemicals easily at will.

    It would be a lot easier to measure as you remove it than to measure as you are adding it.
  • ethicalpaul
    ethicalpaul Member Posts: 4,232
    I think you're right--I had a reason for doing it that way but I can't remember it now
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG