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getiing rid of air

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dmy hvac
dmy hvac Member Posts: 33
just looking for some advice or to hear how other people do it.i am going to empty a boiler this weekend and add glycol to it not sure of name of glycol but its the red kind from (re micheals) ill pump all i can in with a lil submersible pump i have but it doesent really get it over 5psi then ill add water to fill it the rest of the way and to bleed the air out it is a series loop baseboard system what is the best way to bleed air from a boiler any tips?i always do it with the boiler off i shut off all returns and supplies (this one has the shut offs and drain valves)then start by opening one supplt and bleeding out the drain valve on return before the return ball valve till theres no air in hose or spitting out drain valve then proceed do to rest of zones same way.is this the best method any suggestions??

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  • Weezbo
    Weezbo Member Posts: 6,232
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    a spiro vent.

    real good investment.

    clean ,flush the boiler with a quickness.

    dump the entire system.

    lash up a compressor ...

    add antifreeze at the desired mix...

    circ running for a half an hour or so after,... as you add

    the small amounts of anti freeze solution that has now been replacing the space vacated by the air coming out of solution in the spirovent....

    turn the boiler circ off a while...listen for any residual air, tap the relief add a bit more from your pump....crank up the circ again exercise each zone one more time....if your circ pum is stronger than the purge cart pump...you might check any high point coin vents....
  • Ken_40
    Ken_40 Member Posts: 1,320
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    Spirovents are

    great, expensive and rarely needed. The best place to trap air is NOT in a small warm spot (a mechanical vent or air-trol chambered device). The best place is in the boiler block itself! The air comes out of solution at the highest temperature poin of the system. That's inside the boiler, not a few feet away!

    The best place to grab the air is when it's moving slowly where it can nbe "collected." That's alos inside the boiler block! Not a few feet away in a small "chamber" with or without a bristle brush jammed inside.

    Many boilers have an air "chamber" cast into the block. The heat and speed of entraned air is best trapped where the two dyamnimcs of temperature and slow movement are present. That's always inside the boiler block. Weil McLain for one, has that special air catching chamberr cast directly into the block on most boilers. Many other manufacturer's do as well. Placing the vent atop the boiler block is best. On those boilers that do not have block form, anything that can equal the nature of air trapping location should be found and used. If nothing eselmbles slow and hottest locations inside the block, the Spriovent is about as good as there is. But no where as good as a block air-trap seperating casting.

    Although the Weez does mention cleaning, he does not elaborate. You must remove the gunk from the system before putting anti-freeze in. I prefer TSP as the detergent chemical. Some like MEX, Castic soda, commercial boiler-specific cleaners, whatever.

    Just make sure you clean the system first, then rinse it, before adding the glycol. Not doing i will result in a chemical soup being inside made up of some potentially conflicting compounds that could very well attach various materials that were fine as was, but not as will become.
  • Handy_2
    Handy_2 Member Posts: 2
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    loud pipes, no water circulation in one section

    We just moved into a house with gas hot water heat, with baseboard heat. Sometimes, the boiler makes loud noises, as if someone is hitting it with a hammer. It was making noise this morning, and now one of the three heating sections is not getting heat. (Actually, one of eight baseboards has heat--it's the first baseboard in the section.) I felt the pipes (as the basement is unfinished) and the supply lines to this section are warm for the first few feet, and then cold. Any suggestions on the problem or a solution? We're new to this type of heat and would like to be able to solve the problem without expensive house calls. Thank You!
  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
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    No Flow

    Sounds like you've got air in your system preventing the water from circulating around. PURGE
  • wham
    wham Member Posts: 3
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    \"best place\"

    flow not sufficiently reduced in the boiler to properly release the air nor does it have a "collision obstacle" to assist the release to the vent. spirovent is and remains the best way to get it out
  • Ken_40
    Ken_40 Member Posts: 1,320
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    Could you explain...

    why you feel the boiler is not the best place to get air out? It does move slowest there, is the warmest (which is critical to separating air from water), and most well designed boilers provide a scoop or baffle zone that is perfect for the purpose intended.

    What makes the Spiro-Vent better - in light of it having none of the characteristics that can compare to the boiler block area; e.g., warmest water, slowest movement?

    The Spiro-Vent is fine, if the boiler does not have an air-trap internal baffle. But their cost is tough to justify, when any of the other forms of air chamber deice will work just as well. Remember, once the air is out, the air eliminator, regardless of form, cost or style, is worthless!



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  • Weezbo
    Weezbo Member Posts: 6,232
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    Huh?

    If you look real closely at the boilers design quite often in the older pin type boilers there is a "Hummpy" riser chamber that is a very convenient place for a Caleffi auto air...the thing is the water itself carries micro bubbles.

    getting these smaller amounts of air removed, now that is where the scrubbers excel. when it comes to elaborate systems with a great many take offs to remote stations with completely different flow rates in the fluid , i find valves and a by pass at the station with individual purge valves an indispensable value in air elimination much of these depending on the system if they have the two piece Caleffi (check valve with air eliminator) are also good places to eliminate air right then and there...scrubbers are a bit like strainers they collect coagulate and eliminate the air that slips by during the combustion process that are in solution that either were not eliminated in the "Hummpy" reservoir or were moving to the tune of the circulators flow not simply gravity...The old style catch split and release :) were great at getting rid of large air pockets basically by halfs. it basically split large bubbles in half sending the rest down the pike.i tend to think that they were developed for people who thought the auto feeder could do the work of a purge cart..."why bother" type thought process. Every time the burner fires an interesting thing is happening, both with in the boiler and with in the combustion chamber. See, the air we breath has more than simply the Oxygen that we breathe, it has some small traces of many other gasses (and a fairly healthy portion of nitrogen) that simply do not burn. the "Water" or any fluid with the exception of Mercury is carrying impurities within it in the world in which i am familiar ...not to say that within man made environments such as Helium containment fields or containment fields for noble gases the fluid doesn't approach Mercury ,..however ,we are discussing boilers at the moment so lets revisit the topic :) ...

    The containment field say is iron . well, iron oxide itself can be carried along within the fluid. these are like Chunks of air as it were and (is now being addressed with a variety of very cool this century products for its elimination )...while they might be able to find their collective way to an air eliminator at the top of the boiler within the area of the "Hummpy" i am inclined to think for the most part that is not the case. this is also where the scrubber s deflect Entrained O out of the system down as it were into a "debris" eliminator. Ok that is not Down into the make up water stream to become re introduced to the fluid stream ....How am i doing so Far?

    I mean... i could try to help explain many other minor technicalities that many people do not see and have done their best to encapsulate in one word answers.
  • Ken_40
    Ken_40 Member Posts: 1,320
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    It appears Spiro-vents marketing

    has overcome logic.

    "Micro bubbles" are a phrase coined by spiro-vent to create an image of something that does not exist - except in their sales literature.

    There is air in water. How much air can be "captured" is a function of the nature of the air and water. The air that fish breath while in water is not a micro-bubble, (just envision the mindless demonstration Spiro-Vnet shows at trade shows as they put visible air into a closed loop and then how fast those visibe bubbles (micro-bubbles as they refer to them) - exits once they open the Spiro-Vent attached.

    We are almost in awe of the product, as all the visible bubbles dissapear in seconds. Unfortunately, these micro-bubbles they remove are NOT the entraned air we need to remove from boiler water. The air we need to remove from hydronic systems is more like the air fish breath. Without heating the water, no vent on earth can remove the air fish breath. Chemistry can scavenge air/oxygen; and heat can break the air free, but no vent made can remove that air without heat or the other forces. The "demonstration" at the Spiro-Vent booth is very convincing, but fish downstrem of the presumed micro-bubble exhortation would do just fine.

    The reason? Same reason fish can't live on the air outside the water, nor would they ever live on the air displayed as "micro-bubbles." The air (of course we all know it is only the O2 in the air that fish need, just as we also know air does not cause rust, just the O2 within the air that does) but there is no better place to actually remove air from a system than the warmest location (that being in the boiler itself - not somewhere downstream; and, we also know the slower the air in water moves, the easier it is to catch it and eliminate it.

    A foot downstream and while travelling at over 3 feet/second - despite a "ball" of finely stranded stainless "hair" inside the vent's cavity not withstanding - there is lots of marketing, and little evidence the actions seen at the Spiro-Vent booth's demo device, does anything for the air fish breath. Imagine what would happen if the same device was suddenly used in heated water and what you see demonstrated began to work as it may when the water is heated - that being, lots and lots more air being extracted from what you were convinced was already all the air being extracted - actually re-appearing over and over until the water was heated to ~200, when it actually would be possible to declare all contaminating air is almost totally removed...

    This elimination of entraned air is NOT a function of the Spiro-Vent's magical powers, but rather the tenmperature required to allow it to do what any pourger/vent arrangement would do - but not as well or as fast as merely using the boiler tapping for air elimination that was free, included in the manufacturer's boiler casting designs.

    I suggest the "magical powers" we impart to Spiro-Vents is a result of the diaplay they have exploited for years. I also suggest the exact same would occur with any decent purger and 6-dollar vent, in a reasonable time frame.

    The temperature of the water is critical for air separation, not the brand of vent used. Without raising water temps, no vent works. Since there is no debating where water is slowest nor hottest, I simply suggest we re-think the marketing demo from the boiler block venting realities.

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  • Home Depot Employee
    Home Depot Employee Member Posts: 329
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    I disagree

    "The temperature of the water is critical for air separation, not the brand of vent used. Without raising water temps, no vent works."

    Back in the day, I was sucessful selling large Spirovent units 16"-36", which were installed on closed loop 70-85 degrees, and chilled water systems to remove air and realize the pump efficiencies we desired.
  • Brad White
    Brad White Member Posts: 2,398
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    As do I but for different reasons

    Ken said: "The temperature of the water is critical for air separation, not the brand of vent used. Without raising water temps, no vent works."

    To which you replied: "Back in the day, I was sucessful selling large Spirovent units 16"-36", which were installed on closed loop 70-85 degrees, and chilled water systems to remove air and realize the pump efficiencies we desired."


    I should say you were successful in that you sold something that was not necessary, with all due respect.

    Chilled water systems are never run at high enough temperatures to drive air out of solution. They operate between 40 and 60 degrees most commonly and at their warmest, ambient during construction, might approach 95 or 100 on a hot day.

    Water has to be heated to at least 140 degrees (I could be more specific but it is about that and depends on amount of dissolved air and vapor pressure) in order to drive air out of solution.

    I no longer specify air separators on chilled water systems. They do not do anything that a good venting will not do.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Home Depot Employee
    Home Depot Employee Member Posts: 329
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    Dirt separation/removal is just as important as removing entrapped air, for that reason I couldn't think of a better product. Show me a large system in a facility that doesn't introduce air via feed water or chem injection or even large pumps with seals operating either lead/lag or on load that doesn't deal with air issues and I will agree with you.
    "a good venting" is what? Pedro on the clock opening a valve on a routine basis?
  • Brad White
    Brad White Member Posts: 2,398
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    For dirt separation that is a different rationale

    A wye or basket strainer will do what you need for the most part and if your system is that filthy, cyclonic separators can be used in a side-stream application for far less cost.

    Besides, is your make-up water that dirty? That would seem to be the only source of your contamination, assuming you flushed, cleaned and treated the system in the first place.

    Chilled water systems typically are pretty clean compared to hot water and certainly condenser water systems. Not that I would drink it, but it is low in dissolved oxygen and other impurities, especially with the O2 scavengers and molybdate treatments used in most systems.

    Any system that introduces feed water at any rate beyond normal sample draw-off or maintenance has other issues. Besides, when filling those systems, the feed water is passed via a venting chamber (and would be of potable quality even as it is isolated by a backflow preventer). Any air that gets by the venting chamber is vented at the top. Problem solved.

    By "a good venting", I mean, get all the loose air out from all high points and get the system up to pressure. Unless you heat the water as stated, you will not see any more.


    Putting in an air separator for those purposes is an expensive way to do the same thing yet does not scrub out the dissolved air because it is never hot enough to release it.

    If your pump seals are drawing in air, that tells me that the expansion tank is incorrectly located as may be given as standard advice from those behind the orange apron :)

    p.s. Pedro is now your boss. Are you in for it!
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Ken_40
    Ken_40 Member Posts: 1,320
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    If you use a Spiro-Vent to

    filter system water, there are other issues we need to resolve before debating this much further. In fact, there's no debate further required.



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  • Home Depot Employee
    Home Depot Employee Member Posts: 329
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    RoundnRound

    Oh and the discussion circle starts over again as entrained air as HD guy is eluding to causes corrosion in ferric systems that must be filtered. Remove (reduce) air, minimize corrosion.
This discussion has been closed.