possible to revive / clean out a Dunham Air Eliminator?

niftyc_2

The people on this board have been a lifesaver so many times in the past I thought I would call on you again. I have had a new steam guy come out and look at my continually interesting system. He wants me to try to clean out my vintage central Dunham Air Eliminator. He said I can pay him to do it, but that I should give it a try myself and in his experience (actually his dad's) it might work.



I have a very antique 1904 K-M-C vacuum system. The air eliminator looks like this: <a href="http://www.flickr.com/photos/niftyc/3017166931/in/set-72157608801023873">http://www.flickr.com/photos/niftyc/3017166931/in/set-72157608801023873</a>



The Dunham is obviously blocked up -- no pipes near it ever get warm and it vents no air. I discussed this previously on this board and the sort-of consensus was to add venting elsewhere in the system (which I did) and just leave it to be clogged up in place.



Anyway, the new steam guy and his dad (also a steam guy) went over my system and together pointed out that the problem with my prior solution from this bulletin board (which was: leave the Dunham alone and add venting) was that the Dunham isn't just venting air, it was allowing condensate to drain from the air return lines through the outlet at the bottom. (Vacuum systems have air return lines.)



How exactly am I supposed to go about doing this? He suggested soaking the nuts in WD-40 repeatedly. OK I clearly did not ask him enough questions. After I do that am I just going to root around in there with a shop vac? I really am not very handy.



I'd find it oh so reassuring if someone on this board had previously cleaned one of these out and it was actually helpful. If not, I'm not sure I want to dive into this. Any tips on what very specifically to do in order to clean it out would also be great. And I mean as though you were explaining things to a small child, or a homeowner.



Hoping for any tips,

Christian

crash2009

Dunham Vacuum System?

Wow nice old system.  Would it be possible to upload your pictures here on the wall?  I have read about different ones here rebuilding these things.  Where are you?  Is the vacuum pump still working, or at least still there?  We really want to see the boiler room.  I think I have read that there are a couple different kinds of Dunham Vacuum systems. 

niftyc_2

Background

It is not a Dunham's it is a K-M-C it just has a Dunham Air Eliminator added to it.



It's very clever. There was no pump, it was all driven by steam pressure if I understand it.



For my K-M-C I found the patent and the original design: http://www.google.com/patents/US722127.pdf



There's a set of pictures of my system here: http://www.flickr.com/photos/niftyc/sets/72157608801023873/ My system has been modified quite a bit over the years. (Luckily, someone removed the mercury tank.) If you want me to photograph anything else, I will. If it still exists.



My system is also described in:



King, Alfred G. (1915). 500 Plain Answers to Direct Questions on Steam, Hot Water, Vapor, and Vacuum Heating. New York: Norman Henley.



And the principles behind it are explained in:



Snow, William G. (1907). Principles of Heating. New York: David Williams.



Radford Architectural Company. (1909). Radford's Cyclopedia of Construction. vol. 9. Chicago: Radford.



All three of the above are digitized on google books.

crash2009

Oh

I saw the picture of the pressure/vacuum gauge and thought it was a Dunham.  Did they add the gauge when they installed the air eliminator?  What is that small 1/2" line attached to the radiator vent?

crash2009

shortcut

Last summer, moneypitfeeder aka Dee, took her return trap (not a Dunham air eliminator) off the wall and sprayed it with something (something better than wd-40) to loosen the rust.  It looked like a very delicate job, there is a large risk of breaking something.  Here is the shortcut to her well documented project   http://www.heatinghelp.com/forum-thread/136523/guts-of-a-marsh-boiler-return-trap-with-pics investigation  http://www.heatinghelp.com/forum-thread/135119/question-on-return-trap-air-vent  the finished project  http://www.heatinghelp.com/forum-thread/137940/Ive-got-heat-again  Hope this helps you out.  Where are you?

niftyc_2

thanks!

What a great tip, thanks for the links to that thread. Wow that gunk in there is amazing. I'm in Champaign, IL.

niftyc_2

It's an air return line

If you mean this line: http://www.flickr.com/photos/niftyc/3018001000/in/set-72157608801023873, it's the air return line. That isn't a vent it's a trap.



There are no vents anywhere except in the basement -- I think so as to allow the control of the vapor/vacuum effect. The idea is that you induce a vacuum to lower the atmospheric pressure in the system and allow water to boil at a lower temperature. This let you have warm but not a hot radiators, if you so desire. However this system no longer works that way (alas).



So all the air goes from each radiator through these 1/2" lines to the basement air eliminator. Which is clogged. I have added new venting to the air return lines, but condensate seems to be in the air return system and there is no way to get it out if the air eliminator is clogged as that is the only return for the whole air line network.



I guess there shouldn't be any condensate in the air return lines in the first place -- all traps are working I checked them. However my heating guy's point is that even if a tiny bit got in there once every year there is nowhere for it to go right now if that Dunham's air eliminator has no outlet.

crash2009

Your welcome

 There is a lot here on the wall on the subject of "Dunham air elininator" try searching the wall, there is so much written on your subject you could read for days.  http://www.heatinghelp.com/forum/search  here is one with some tips on how to get those things running again  http://www.heatinghelp.com/forum-thread/84849/two-pipe-steam-boiler-Dunham-air-eliminator  IL huh we are practicly neighbors Ann Arbor MI

niftyc_2

It wasn't full of gunk after all.

When have I ever opened a pipe in this system to find good news? Soaking the bolts in WD-40 allowed me to open up the Dunham Air Elminiator and (drumroll) I don't think it was the problem. It had a thin layer of gunk in it but really not very much at all. You can see it there on my finger. Indeed the Air Elminiator vent was frozen but as I've since added other venting to the system this isn't my problem. I've uploaded pictures for your viewing pleasure just to close out this thread. Thanks for all the advice.



Now on to my next attempt to solve my problem: http://www.heatinghelp.com/forum-thread/139678/five-cold-radiators-on-three-risers-Im-scratching-my-head

Mark N

Vacuum

The one picture show a small metal disk. If this system no longer works in vacuum you probably need to remove that disk. I think the disk wouldn't let air in after the system dropped into vacuum.

crash2009

Remove the vacuum check disk,

 and install a Gorton 2 in the hole.  If this worked for them  http://www.heatinghelp.com/forum-thread/84849/two-pipe-steam-boiler-Dunham-air-eliminator  I don't see why it wouldn't work for you.  Near the end of the thread Stuart says all's good

niftyc_2

need something that closes to water

Hmmm... I'm not sure the Gorton's would be a good idea. My system may be a little unusual. There is no expectation that steam will ever reach that point in the system (as the Dunham Air Eliminiator was connected to the air line), but water might. I gather that's why the Dunham worked the way it did -- the float pictured closed the vent to water. If I understand what the thermostatic thingy in the Gorton's is for, in this situation it would spit water. I think it might be best to just leave it frozen shut, or cut it out entirely and do my venting elsewhere.

crash2009

I am not sure either

Maybe you should wait for a professional opinion.

niftyc_2

I'm just glad...

I'm just glad someone replaced the original mercury tank with the Dunham's! I could have worse problems to clean up.

Dave in QCA

Don't act to hastily

The Dunham Air Eliminator and Air Check is a great piece of equipment.  If they were still on the market, I'd be buying one.  If I could find a used one, I'd buy it!



The Air Eliminator of course allows the air to vent out, but if the water backs up into the return line because of boiler pressure, the float closes the port, allows pressure to build in the return line and thus, the condensate would begin to return to the boiler.  The leading main vents on the market today have float devices in them, namely the Hoffman 75 and the Gorton #2.  However, about everyone that I have heard from who experienced a water backup into their main reports that water squirted from the vent.  So, perhaps the float slows it down a bit, but is not reliable.  I assume that the float in the Dunham A E is more reliable.



As to the Air Check, current thinking advises that gas or oil systems should not run in vacuum and therefore, and vacuum producing device should be removed.   However, there is an ongoing debate on this issue and I suspect there will be more discussion and interest in the subject.  Note that most, if not all of the companies that marketed vacuum vapor systems stated that they could be used on coal, gas, or oil fired systems.  The inventors are long gone, and the people who understood and maintained these systems are very obscure and special breed of "dead men".



If it were my system, I'd clean up the A E and make sure it works correctly.  I'd polish up the disc in the air check, and I'd put it back in.



If you decide to take the disc out, I'd save it.  If you decide to remove the whole Dunham device, let me know, I'd offer to purchase it from you!

Ban

Please

Do not throw away that disk in the check valve!