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Air trapped in boiler

savage54
savage54 Member Posts: 35
Hello: Can't seem to get all the air out of the system. Installed a new ball valve in the supply (valve #3). Closed valve #3, opened valve #4. Had a hose in a bucket hooked up to valve number 4. Pulled lever on make up water supply, let run for a few minutes, only a little air came out. Next try, closed valve #2 hooked a hose with 40 psi to valve #1, opened valve #4 ( with a hose in a bucket) then opened valve # 1, hoping to push all the air trapped in the supply piping out valve#4. Still have air trapped in the boiler. Help
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Comments

  • furnacefigher15
    furnacefigher15 Member Posts: 514
    What type of radiators, and what pressure is in the system?
  • savage54
    savage54 Member Posts: 35
    The system is a Weil McLain 100,000 btu, feeding cast iron baseboards, single level ranch type home. I posted this problem on this site in January 2015. Thanks
  • savage54
    savage54 Member Posts: 35
    Oh the pressure is at 15 psi
  • furnacefigher15
    furnacefigher15 Member Posts: 514
    edited December 2016
    Was I the first reply in a year? Thats rediculous!

    Just vent the air at the cast Iron baseboards Unless there are no coin vents there.

    Try closing valve 2 and venting from valve 1 with the fast fill open.

    Also is there a check valve integrated into the pump? If so that may be mucking up the works.
  • savage54
    savage54 Member Posts: 35
    Have bleed all the cast iron units. The air sounds to be trapped in the boiler mostly. The air hammer and percolation sound is loudest at the boiler. Two other person offered suggestions to try, which I did, but that was almost a year ago, and didn't fix the air problem. As you can see from the picture it is a pretty simple system. The spiral therm air eliminator is at the highest point in the system, which should eliminate any air trapped in the supply piping. The 3/4" with the tee and air bleed with valve #4 on it is my question. Is their a internal baffle? The instructions that came with the boiler said that line should go to the air tank.
  • savage54
    savage54 Member Posts: 35
    Oh, and their isn't a internal check in the circ pump. I will try what you suggested. Close valve #2 and bleed out of valve #1, but will have to do that tomorrow. Will let u know what happens. Thanks for the help.
  • furnacefigher15
    furnacefigher15 Member Posts: 514
    Yes, I imagine there is a baffle inside the boiler where valve 4 is tied on, but I would think that the air vent would handle that air.

    The other thing to do is make sure the pump and boiler are off at time of venting, and also close the valve to the expansion tank as well.

    When you do the venting attach a hose to valve 1 and run it to a drain or outdoors and let it vent for a while, like 10 minutes to give the air time to escape.
  • Nice soldering job!

    I would increase the pressure to just under 30 psi; makes the bubbles smaller and easier to move around (thank you, Mr. Holohan). Also, add a spoonful of dishwashing detergent to free up those sticky air bubbles (thank you, Mr. Eatherton).

    Tell us how it goes.

    Happy holidays!
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    kcoppGordy
  • savage54
    savage54 Member Posts: 35
    Thanks, for the complement and the suggestion. Will post what happens.
  • savage54
    savage54 Member Posts: 35
    Well furnacefigher15: I flushed the supply piping system today. I closed valve 2 and had a hose hooked to valve 1. Closed the valve above expandtion tank, then pulled lever up to give the system line pressure (40 psi ) would throttle valve 1 (drain ) just so the the relief would not lift. Probably 28 lbs, let run like this for ten minutes. All this was done with the power to the boiler was off. Removed all the flushing stuff from the piping system, valve1 closed, valve 2 open, put make up water to 15 lbs, opened valve above expansion tank, put electric to the boiler. After the water heated up to 100f, the air noise was still their. As the water get hotter (160f ) and above the noise gets quieter. And thoughts?
  • savage54
    savage54 Member Posts: 35
    Alan: I am running the system at about 25 psi right now, still have trapped air. Thanks for the input.
  • lchmb
    lchmb Member Posts: 2,997
    How about a picture of your radiators?
  • MilanD
    MilanD Member Posts: 1,160
    I wonder if it has to do with the pump and delta p. You are pumping out of the boiler and not into, like your manual shows. You may be creating a condition by which your air vent sucks in the air? Maybe?
  • Steamhead
    Steamhead Member Posts: 16,459
    Sure it's not percolation rather than trapped air? Percolation is when water along the bottom of a boiler has to come up through a layer of gunk on the bottom- some of this water turns to steam before it comes through, causing the noise.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    savage54
  • savage54
    savage54 Member Posts: 35
    Here's a pic of the baseboards, Ichmb
  • MilanD
    MilanD Member Posts: 1,160
    The vent between 2 and 3 valve, and maybe even the one at 4. This could explain air in that location. You may need to do pump per manufacturer spec...
  • MilanD
    MilanD Member Posts: 1,160
    Or use circulator with smaller head...
  • savage54
    savage54 Member Posts: 35
    Steam head, I hear what u are saying, the boiler has been in operation since 1998. Using soften well water for boiler make up water. The sound is like a perculation sound. How would or could u clean it out?
  • savage54
    savage54 Member Posts: 35
    MilanD, when the boiler was new the pump was on the return. I moved it to the supply side when I added the spiral therm air separater, as per their piping drawing.
    MilanD
  • MilanD
    MilanD Member Posts: 1,160
    Maybe your scrubber air vent went bad? Or one on 4. That water should cary any air to the highest point in the system, no? On the way, the scrubber would catch it, or vent at the rad if you have one. If your pump creates drop in p that vent now can't handle, maybe one on 4, it takes in air, and scrubber takes it out, so now you have gurgling, and system works...

    Also, if I am not mistaken, you shouldn't be taking in any make up water once the system is filled and running.

    Btw, my comments are from an end-user and not a pro. I'm thinking the way I'd do for my system. I have Smith ci boiler, with air tank (old school), taco 007 pumping into the boiler. No scrubbers, no air vents. Air pockets with cold weather just the other day collected at the highest rad. Wfiw.
  • Zman
    Zman Member Posts: 7,495
    I wonder if your vents are plugged. Your system is piped quite well and you seem to be purging correctly. Do you hear or feel air escaping ever? I might be worth disassembling and cleaning.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Steamhead
    Steamhead Member Posts: 16,459
    savage54 said:

    Steam head, I hear what u are saying, the boiler has been in operation since 1998. Using soften well water for boiler make up water. The sound is like a perculation sound. How would or could u clean it out?

    You (or preferably a pro) would have to use some sort of cleaner in the boiler water. Rhomar Water makes some good stuff for this.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    savage54
  • savage54
    savage54 Member Posts: 35
    MilanD, system worked fine since 1998. In 2014 I removed a big air tank they had piped in the attic (causing ice dams on the roof in the winter), to a bladder tank, that yo see installed in the pic. Every since then I have had this air problem.
    MilanD
  • savage54
    savage54 Member Posts: 35
    Zman, I have purged to air out of all the baseboards. The spiral therm air eliminates is only 2 yrs old. When I have worked on the system I can hear air entering in the spiral therm, then when I purge the system of the air, I can hear the spiral therm expelling the air. Indication that it is working.
  • MilanD
    MilanD Member Posts: 1,160
    Ok, I see the install setup. If it's not air vent, maybe expansion tank?

    What's the pressure in your expansion tank set to? I may be wrong, but if it's like on hwh, it should match op pressure of the system prior to being connected to the system. I may be stabbing in the dark here and you probably already thought of that. This is a strange one. Maybe really just needs a good cleaning although you said it started acting like this when the tank was moved...
  • MilanD
    MilanD Member Posts: 1,160
    What happens if you briefly isolate the tank?
  • savage54
    savage54 Member Posts: 35
    Expansion tank pressure is set to the boiler operating press 20 psi
  • savage54
    savage54 Member Posts: 35
    Pressure in boiler goes up
  • furnacefigher15
    furnacefigher15 Member Posts: 514
    Steamhead might be on to something. That system is piped right for venting, and its piped to pump away from the exp tank. Thats all current standard practice and works very well. The benefactor of this website even has a book about it. "Pumping Away" - Dan Holohan.

    Even if the piping was laid out poorly for air venting, you have manual air vents at each baseboard.

    If you run just the pump, is it quiet?

    Does the noise only occur when the burners are on?

    If so, thats caused by a layer of scale build up in the bottom of the cast iron sections that get super hot, and flashes of steam are made - only fix is strong chemicals - I advise consulting a pro for sure to handle that job.

    I would recommend Rydlyme as the cleaning agent.

    If the noise happens all the time - it may be that the pump is too big and you here velocity noise.

    Air normaly sounds like water falling inside the piping, like a trickling noise.
    GordyMilanD
  • savage54
    savage54 Member Posts: 35
    furnacefigher15, That is worth a try, just run the pump without the boiler fired up. I will try that and let u know what I hear.Thank & Have a Merry Christmas
  • savage54
    savage54 Member Posts: 35
    Just wanted to say a Big Thankyou for all of the guys that offer help with the boiler air problem. Have yourself's a Very Merry Christmas.
  • MilanD
    MilanD Member Posts: 1,160
    Do report back what it was in the end. This is like a mystery novel! Merry Christmas to all!
  • savage54
    savage54 Member Posts: 35
    Will do
  • savage54
    savage54 Member Posts: 35
    Hello Furnacefigher15, Tried today only running the pump with no fire to the boiler, quiet. No noise at all, when the burners kick on after a minute or two you start to hear the noise. I think you and steamhead solved my air ( or so I thought ) problem. I am in search of a business that can chemically clean out the boiler. I will post the final results after I have that done. Thank you's again for your help, I know your time is is very valuable.
    CanuckerZmanMilanD
  • furnacefigher15
    furnacefigher15 Member Posts: 514
    Anytime.
    savage54
  • lchmb
    lchmb Member Posts: 2,997
    Ive had luck solving this type of issue with a bottle of 8 way...may be worth a shot...
  • savage54
    savage54 Member Posts: 35
    Sorry, do not know what eight way is.
  • savage54
    savage54 Member Posts: 35
    Thanks
  • savage54
    savage54 Member Posts: 35
    Well I followed Ichmb suggestion of trying a bottle of 8 way. Received it today and mixed it in with the boiler water and it solved the perculation noise I was hearing for 2 heating seasons. Can't wait to go to sleep with no noise from the boiler. Thanks to all the guys that helped in solving this problem. A very Happy New Year
    Zman