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    Vacuum air vents on one-pipe systems (57 Posts)

  • Ban Ban @ 9:18 AM
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    Vacuum air vents on one-pipe systems

    I don't understand why there aren't any manufactures who make air-vents for one-pipe systems that check the air. I am trying to understand what benefit there is to allowing the atmosphere back into the system after the radiators have condensed and so far I see none. I am not interested in creating an air-line or Paul system with forced vacuum. I am only interested in having the air exit and not return. Can someone please inform me why this is?

    Thanks,

    RB
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • ChrisJ ChrisJ @ 12:09 PM
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    Vacuum

    I also have wondered the same thing, however I believe there are two reasons.  The first is balancing, it would be impossible to balance a single pipe system operating under a vacuum.  The second reason is condensate, , I've heard there would be issues with getting condensate back but again I have not tried it and have very little knowledge on the subject.
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures updated 6/5/14.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#
  • Ban Ban @ 12:23 PM
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    I understand but,

    I think the balancing could be an issue but wouldn't be an issue if you did it right. You could drill the orfice size to match the need of the radiator or simply add more holes. You could also add a slot in the cap where you could vary the amount of air by a valve, or lever.

    Condensate: this should not be a problem at all. Water can move around freely in a closed system, right? Does it move around in a closed container such as a bottle? The water would simply displace the air.

    Thanks for your reply, I want to discuss this more.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • ChrisJ ChrisJ @ 12:41 PM
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    Orifice

    Drill an orifice in what?  If you put an orifice in the steam pipe condensate cannot leave.
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures updated 6/5/14.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#
  • Ban Ban @ 1:00 PM
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    Orfice

    I was thinking on the exit of the vent after it passes the check.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Steam_Starter Steam_Starter @ 12:53 PM
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    Think of a straw...

    If a one-pipe system prevents air from getting back to the system there would be a loss of water from the boiler due to the fact that it is "trapped" in the risers.

    Think of a straw...my kids favorite thing to do at a restaurant...stick the straw in the drink, cover the end, then pull it out.  Water stays in the straw because there is no "air behind water" and it creates a vacuum.  And then at that point, the water that is "trapped" in the risers will prevent the steam from getting to the rads.  It will be running interference and turn the steam back to condensate as soon as the two meet, thus creating the dreaded water hammer.

    Unless I am thinking of this wrong...which wouldn't be the first time...

    JLG
  • Ban Ban @ 1:03 PM
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    Straw,

    Except for the radiator nor the pipe will be completely filled with water to prevent flow. I think gravity would still bring it down being that it will not be occupying the entire diameter of the inner surface area of the pipe. I really want to believe this is possible.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • ChrisJ ChrisJ @ 1:08 PM
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    orifice no work

    If the system holds vacuum at all it would balance throughout the system over time and all radiators would pull steam fast and what you get is what you get, in my opinion.

    My system would be a nitemare as some runouts are 20' long while a few are only a few feet.
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures updated 6/5/14.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#
  • Ban Ban @ 1:16 PM
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    I have no idea

    That is why I started this thread. I am really excited for the discussion. I also plan on testing it on a small system. I have an idea to make the vents but as steam starter stated I am a bit concerned about the condensate.

    Theoretically, in a one-pipe system, after the entire system has filled with steam and the vacuum starts to occur will the condensate water be allowed to drain back to the boiler or not?
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Pumpguy Pumpguy @ 1:36 PM
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    Paul Systems

    First off, please understand that I am a pump guy, and only deal with pumping equipment on steam heating systems.  While I know a fair amount about system piping details and fluid dynamics, my specialty is pumping equipment.

    An interesting experiment would be to substitute the radiator's air vent for a Paul valve with a check valve on it's outlet air line side.  The outlet side of the check valve would be open to atmosphere.  A Paul valve, from what I understand, is a thermostatic valve that allows air to pass through it but not steam.  Again, if what I understand is correct, it operates like a thermostatic radiator trap on a 2 pipe system but is smaller to allow air venting to be uniform so you don't get overheating in one area, and underheating in another.

    In a one pipe system, or 2 pipe for that matter, condensate always flows by gravity to the lowest point in the system.  This is true regardless if the pressure in the line is at pressure or vacuum. 

    Vacuum in the steam lines, boiler, and radiators is a good thing in that you can make  steam at a lower temperature, and don't have to use steam pressure to push the air out again at the next cycle.  Also, you're not constantly introducing oxygen into the system so corrosion would be less of a problem. 

    Operating at vacuum might have a negative effect on the boiler's pressuretrol, but that's something I do not know anything about. 

    I'm probably displaying more ignorance than knowledge with this post so please take it accordingly and add corrections as appropriate.
    Specializing in vacuum pumps for steam heating systems, especially older Nash Jennings units. We build new ones too!





    Please visit our website www.nashjenningspumps.com for more information
  • Ban Ban @ 1:42 PM
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    Yes!

    My thoughts exactly! But would it work? Could you use a Hoffman #3 (in this case) and get results? Has anyone ever tried it?
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Charlie from wmass Charlie from wmass @ 3:55 PM
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    Leaks are on reason for lack of vacuum vents

    a pressure leak is easier to find. The Vacuum leaks around valve stems and other fittings allow air in and do not allow vacuum to form evenly. If you have vacuum you need to have it everywhere not just in one radiator. The straw effect occurs only if the whole system is not to sub atmospheric pressure. You could also have steam flashing to steam in the piping as the pressure drops. I also would not try this on a gasketed boiler. You could crash your boiler or radiators if you did a really good job of making a vacuum. You would need to include a vacuum relief valve to prevent too much vacuum.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • ChrisJ ChrisJ @ 4:06 PM
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    Vacuum

    Charlie, wouldn't this be a concern on my EG series boiler just in normal use?   Figure if it ran for a good long time and all of my vents got good and hot, they wouldn't open for quite  awhile after shut down allowing a pretty strong vacuum.  Or,  are we talking a vacuum that would form after several cycles, each one squeezing a little more air out?
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures updated 6/5/14.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#
  • Charlie from wmass Charlie from wmass @ 10:10 PM
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    modern vents

    have vacuum breaking built into it. even if they are hot they will not allow a vacuum to form. Yes EG boilers have gaskets between sections.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Ban Ban @ 8:09 AM
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    Interesting

    So you think that even a slight vacuum could cause problems with the neoprene gaskets in the Weil-McLain boilers? Wouldn't the gaskets be able to withstand a negative pressure at the same percentage as positive?
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Mark N Mark N @ 5:58 PM
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    Vacuum Vents

    In the days of coal fired boilers the vents worked fine, They don't work with intermitttent firing. The coal burned for hours and you were able to get all the air out of the system. You can't do this with intermittent firing. The air that is left in the system expands in the vacuum and causes all kinds of problems. It is covered in LAOSH.
  • Ban Ban @ 7:03 PM
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    Coal

    I am apprehensive that a vacuum system would only work in conjunction with a coal fired boiler. I would like more information on the air that is in the system and the problems it causes and why they are caused. If a manufacturer were to make brand new, well sealed vent that would act as a 1) float for water, 2) a vent to release air, and 3) a seal to prevent air from returning into the system--and they all functioned properly--why would there be a problem?
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Ban Ban @ 7:10 PM
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    adjustable orfice

    I should also add that the vent should have an adjustable orifice for sizing and balancing.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • SWEI SWEI @ 8:54 PM
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    Coal, or

    a modulating gas burner.

    I'm still convinced this is a largely unexplored option for steam.
  • Mark N Mark N @ 7:25 PM
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    Air

    It is my understanding that all the air has to be removed from the system. The coal fired boiler allowed this to happen. With intermittent firing the boiler turns off long before all the air is expelled and the vacuum that forms from the collapsing steam closes the vacuum check. The air that is in the system expands to fill the vacuum. I would assume the if the vacuum isn't relieved and the vacuum checks are still closed the next time the boiler fires the flow of steam will be blocked by the air that can't get out.
  • ChrisJ ChrisJ @ 9:03 PM
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    What about

    Producing a vacuum with a simple pump?

    But at what point would running a vacuum pump start to eat up any savings? I'm not sure how much a vacuum you need, but an old refrigerator compressor could be used to pull a vacuum. You'd need to keep it lubricated some how though.
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures updated 6/5/14.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#
  • BobC BobC @ 9:26 PM
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    pump

    Something like this might work for a long firing system. i don't know what kind of life it would have. From Surplus Center
    Smith G8-3 with EZ Gas @ 84,200 BTU, Single pipe steam

    Vaporstat with a 12oz cut-out and 4oz cut-in

    3PSI gauge
    This post was edited by an admin on January 15, 2013 9:28 PM.
  • SWEI SWEI @ 9:45 PM
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    life

    I used a 3,450 RPM Gast air pump to feed a pond aerator running 24x7 and we had to have it rebuilt in just a few months.  They're probably fine for intermittent duty.
  • Mark N Mark N @ 6:55 PM
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    Pump

    Since the vacuum vents are no longer made the whole point is moot. Paul vents are still made. Get the Paul vents add the air lines and a pump and you're in business.
  • Eastman Eastman @ 8:39 PM
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    Vacuum, Modulation, and Efficiency

    Vacuum seems to be the only way to modulate the output of steam.  There are no residential modulating steam boilers that I am aware of.  The only choice seems to be a mod/con with some kind of indirect coil.  If you can't lower the operating tempretures then you can't use a mod/con boiler for this purpose.  Achieving thermodynamic equilibrium appears to be the biggest major contribution to system efficiency in the residential market.
  • Ban Ban @ 7:45 AM
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    The whole thing is moot...

    Correct. It is moot unless a vacuum vent is made or possibly using a Hoffman #3 without the line(?). There is no value to any of this if there is something that I am missing to cause this not to work. Fortunately vacuum on a one-pipe system hasn't been challenged very well. The largest negatives to this concept to date are:

    1. Air not being fully purged from the line on fire-up and causing some kind of terrible pressure/balancing problem after the system starts to go into a vacuum

    2. Gasket-style boilers not being able to withstand the vacuum pressure.

    3. And vacuum air vents not being produced for one-pipe systems.

    So the first one i'm not so sure about, the second one seems fairly unlikely as well however I did leave a voice-mail with Weil-Mclain yesterday asking that very questing, so we will see. The third one is a good point but not necessarily hard to overcome with simple hardware.

    If there is anything missing outside of these three things on why this wouldn't work please post it!
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • jumper jumper @ 3:33 PM
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    tried before

    Vacuum vents were sold before WW II. I think sometimes systems with them worked better but sometimes there were complaints so Hoffman stopped promoting them and eventually discontinued selling them. It is moot because nobody is going to try it again.

    I agree with ChrisJ that you shouldn't need vents at all if the system is reasonably airtight. Just evacuate the air out with a pump or ejector. You can get a harder vacuum that way than using steam to push air through check valves.
  • Ban Ban @ 4:32 PM
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    Complaints to Hoffman

    Do you know what kind of complaints there were? Why did people stop using them? I am not concerned on whether it will be produced in the future or not. My concern is will it work or not.

    "I agree with ChrisJ that you shouldn't need vents at all if the system is reasonably airtight. Just evacuate the air out with a pump or ejector. You can get a harder vacuum that way than using steam to push air through check valves."

    So with this you are saying that you would plug all of the radiators and main vents, then create a vacuum on the system and then close it and walk away?
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • ChrisJ ChrisJ @ 4:34 PM
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    Nope

    I think that vacuum pump would need to run constantly due to leaks in the system.  These arn't brazed or soldered hermetically sealed systems, you WILL loose vacuum no matter what.

    I also think having small copper tubing run to each radiator in place of the vent hooked to a central pump that operates on boiler fire up could work too.  It would help create vacuum at the radiators first.
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures updated 6/5/14.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#
  • Ban Ban @ 4:33 PM
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    WWII

    Seems there were a lot of things that worked well prior to World War II.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Mark N Mark N @ 7:08 PM
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    1 pipe vacuum

    I don't have any idea when they stopped manufacturing the vacuum vents. They most likely stopping making them because nobody was buying them. I would think people stopped buying them because they didn't work with oil or gas. If the dead men of 70 to 80 years ago couldn't get it to work. What has changed to make it work today?
  • Charlie from wmass Charlie from wmass @ 6:53 AM
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    not all dead men

    were created equal in skill. I typed in a 3 paragraph answer as to what killed the steam vacuum air vent. It then deleted off the screen. To sum it up, lack of knowledge and skill of the people installing and maintaining heating systems is why the vents went away and why they will not come back. There are not enough people doing things right to sell enough vents for the industry to make a vent they only sell every decade or so.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Rod Rod @ 7:45 PM
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    Vacuum Air vents

    Mark-  Good Point!
  • jumper jumper @ 8:29 PM
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    six kinds of steam heat

    Somewhere on this site is an article with this name. It discusses the advantages of one pipe vapor. That's what it was called evidently. The DOA didn't have to balance heating because each room had a double hung thermostat.

    As for sealing a system, if it is exposed you could gloop the joints. With modern chemistry there must be a way to block both air and steam. My friend installed steam heat systems without threaded pipe fifty years ago.
  • Eastman Eastman @ 12:32 AM
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    The article...

    The article seems to imply the chief culprit for oil and gas was the use of air vents to balance the system.  A vacuum break was recommended to restore the balancing function of the vents after each cycle.  It also mentions single pipe vapor systems would naturally balance with coal at the steady state condition.

    Can modern TRVs be used in combination with the vents to balance a vapor system?
  • Gordo Gordo @ 1:11 AM
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    I was on a job not long ago

    that had Hoffman vacuum vents on the mains and all the radiators.  They were all working.  The system held a vacuum continuously and heated evenly and quickly. The customer did not want me to touch it (I didn't question that!).

    I was there to replace the sightglass gaskets.  He knew they were leaking because the sightglass had bubbles in it due to the air being sucked in.  I had to get it real tight to stop the vacuum leak. He was most definitely NOT interested in a sightglass blowdown valve.

     Hours later, I was called back because the old sightglass had cracked. How did he know? It started bubbling again.
    Vacuum leaks are a pain.
  • Ban Ban @ 7:24 AM
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    No more to talk about

    There you have it. Gordo witnessed it and by the sounds of his customer they were very protective of this rare breed. Now I have to test it and encourage you to do so as well! I will update.

    Thanks everybody!
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Ban Ban @ 7:24 AM
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    No more to talk about

    There you have it. Gordo witnessed it and by the sounds of his customer they were very protective of this rare breed. Now I have to test it and encourage you to do so as well! I will update.

    Thanks everybody!
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Gordo Gordo @ 9:24 PM
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    Well, That Vacuum System was

    definitely "one for the books".  But I advised the customer that he had a charmed system.  I suspect that if only one of the vacuum vents fails, the fairy dust will be released and it will break the spell.

    I've seen other one-pipe vacuum systems, but with that one exception they were in failure spiral.  One radiator will heat normally one cycle or for several days. Then randomly stop heating.  Other radiators will start heating.  Then stop.  There is nothing for it but to replace the vents with current models.





      
  • Eastman Eastman @ 10:24 PM
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    Have you seen

    Have you seen any system that implemented the possible solutions outlined in "Six Kinds of Steam Heat"?
    This post was edited by an admin on January 18, 2013 10:43 PM.
  • Eastman Eastman @ 2:48 PM
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    More talk...

    Have you seen this article?

    http://completewatersystems.com/2011/05/%E2%80%9Cvaporvacuum%E2%80%9D-dos-and-donts/

    "Vapor/Vacuum" Do's and Don'ts  -- reprinted from CounterPoint Jan 95, vol. 2 issue 1

    "Nowadays, however, most of us fire our steam boilers with gas or oil... ...This cycling creates problems in systems that have vacuum vents. The
    vacuum quickly forms when the burner shuts off. Any air that doesn’t get
    vented on the first cycle expands greatly, blocking the movement of the
    steam “vapor” to the radiators. And because gas and oil burners shut
    off completely between firing cycles, there’s no longer a hot bed of
    embers to keep the low temperature water boiling. When you mix vacuum
    vents with gas or oil, you usually wind up with uneven heat and
    callbacks. You also wind up with condensate that doesn’t return quickly
    enough from the system, and that can lead to water I level problems in
    the boiler."

    Automatic firing one pipe problem summary:
    a)On/off automatic firing creates a hard and fast vacuum. 
    b)The deep vacuum causes remaining air to expand greatly.
    c)The greatly expanded air trapped in the system blocks the flow of heat from any residual boil.
    d)Condensate tends to get trapped because air is not allowed back into the system.
    e)If the system remains sub-atmospheric on the next cycle, the air vents will not operate and provide uniform distribution.

    According to "Six Kinds of Steam Heat," one possible solution for "one-pipe intermittent vapor" was to add a vacuum breaker to prevent hard vacuums from forming in between firings.  Another was to break the vacuum at the beginning of each call for heat.  The noted disadvantage of these solutions, "It accentuates the familiar disadvantage of oil burner firing whereby heat is produced in great quantities for short periods, followed by long "off" periods."  I like the idea of breaking the vacuum on a call for heat, I don't see the downside over current practices.

    Are there buffer tanks that could be adapted for sub-atmospheric steam production?
    Other than the vacuum vents or possibly a pump, it seems like this is the missing piece to make "one-pipe intermittent vapor" work.  Break the vacuum at the beginning of each call for heat to provide uniformity, extend the firing cycle with an insulated buffer tank, extend the boil with the buffer.
  • SWEI SWEI @ 12:28 AM
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    solution

    Wouldn't a modulating gas burner be an even better solution?
  • Eastman Eastman @ 1:09 AM
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    That would be a big step in the right direction.

    But who makes such a thing.  One of us needs to piece together a modulating power burner.  In all honesty, we should form a shell company to ask for sample parts from the major players, develop the operating parameters based on the combined experience from this board, then buy the parts in mass and distribute.
  • SWEI SWEI @ 9:46 AM
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    they do exist

    Powerflame X4M and Midco Low NOx have been discussed here, but they don't come in typical residential sizes and there are no off-the-shelf controls available.
  • Eastman Eastman @ 11:18 AM
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    "no-off-the-shelf controls"

    Right, as a minimum one would need to program a microcontroller board to handle the various aspects of flame control and integration, but these chips are cheap and readily available.  As a starting point, I suggest using spare parts from a giannoni style mod/con, substituting our own programmable controller.
  • SWEI SWEI @ 12:35 PM
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    controls

    Plenty of DDC manufacturers make suitable controllers, and Mark S here has been rolling his own http://steamheat.thestaytons.net/ http://www.heatinghelp.com/forum-thread/143517/A-Steam-Enthusiasts-Outdoor-Reset-Control
  • Mark N Mark N @ 5:35 PM
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    Parts

    Richard where are you going to get the vacuum vents? Let us know how your test goes.
  • jumper jumper @ 12:46 AM
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    don't need no stinking vents

    Forgive me for repeating. On a one pipe system a vacuum generator anywhere will do. A water powered ejector can pull down to negative twelve psi in winter. If you have an air compressor an air powered ejector can suck even harder. At such low pressure the system will be filled with saturated steam even during off cycle.

    Vacuum one pipe was never promoted because there's nothing to sell. No vents, no traps.
  • Eastman Eastman @ 1:11 AM
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    Has anyone tried this?

    Has anyone tried this?

    Or, why hasn't anyone tried this?  (I thought this was done in commercial buildings.)  Are we back to the gasket issue?
    This post was edited by an admin on January 19, 2013 1:24 AM.
  • Mark N Mark N @ 8:21 AM
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    Hoffman #2

    This is from the Library

    http://www.heatinghelp.com/files/articles/1310/128.pdf
    This post was edited by an admin on January 19, 2013 8:33 AM.
  • Ban Ban @ 2:49 PM
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    Library post

    Thanks for the Library post. I am working on the valve right now. It is going to take me some time to finish it. I will post when I am done.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Eastman Eastman @ 5:11 PM
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    how is it going Ban?

    Have you made any progress?
  • Ban Ban @ 5:23 PM
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    Actually,

    Yes! I was working on it yesterday. It is almost complete but the valve didn't work quiet right yet. I need to make a few modifications still. I will post a photo when I'm finished.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Ban Ban @ 5:25 PM
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    Gasket-Style Boilers and Vacuum

    I spoke with technical support for Weil-Mclain. They said their boiler can absolutely run in a vacuumized system. So everybody that was worried about that can now relax.
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Ban Ban @ 4:10 PM
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    Progress so far...

    Attached below is the prototype of a new add-on to a standard Maid-o-Mist air vent which converts the valve to allow a vacuum to form! After the air has been bleed out of the radiator a check valve stops air from entering back into the system just as in the Hoffman, Heat thief sales ad. I used Jacobus vents because they are inexpensive, durable, easy to thread on to and can be fitted to balance a one-pipe system easily.

    I have not fully tested the valve yet. I have to make a few design changes before it can be submitted to a real live steam situation. I understand some of you are a bit anxious for my results, as am I, unfortunately, at this moment time is hard to find and I have put this aside for longer than I would have liked.

    Have a great day!

    Richard
    Richard Ban


    Detroit, Michigan (Dunham 2-pipe vacuum)
  • Bio Bio @ 1:11 PM
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    Wondering

    Ban, Any updates? Any progress?
  • conversiontime conversiontime @ 8:10 AM
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    thanks for hoffman 2 document

    Realize this is old thread but the hoffman 2 article/ad/promo from 1927 was great. My current abode was built in 1929 and have been here since 2010. The heat system is one pipe steam since day one but certainly original boiler was coal (old rakes still in basement). The dead men mains and runs to rads are original piping and probably the rads.

    Anyhow last year when converting from oil to gas I read dans books and fixed many uneven heating issues myself like new venting, therm, etc while the pro converted the boiler. When I removed the old main vents (gorton 16) and likely original, I could not figure out why they were labeled vacuum as this seemed standard one pipe system. But the other night when cleaning some shelves in basement I was looking at two old vents that were removed by somebody, sometime in the past. Then realized they were hoffman 2 vacuum vents, found this thread  and the old hoffman 2 publication = it all made sense.

    Hard to believe the old vacuum main vents apparently stayed in place from 1929 to fall 2012 when I removed them and replaced with gorton2. Untold amounts of heating oil must have been spent over the decades post coal convert to move that air and numerous rad vents blown over the years. These two gorton2 survived somehow as originally there would have been 10 total. The 16 gorton were really rusted in and took a almost 4 ft breaker to remove. Now realize they are all pretty cool pieces of history.
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