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clogged air return lines on a 1906 K-M-C vacuum system

I am still trying to slowly improve my 1906 K-M-C Vacuum System. Thanks again to everyone on this board who helped me last year! I have become a convert to steam and I am a big fan of my system.



As you steam junkies already know, my radiators work like a one-pipe system but they have tiny little air lines coming out of them that run to the basement where there is a central air vent so the entire system can operate in vacuum or vapor. Here is a picture. The air return line is the thing on the right.



<a href="http://www.flickr.com/photos/niftyc/3017167615/in/set-72157608801023873/">http://www.flickr.com/photos/niftyc/3017167615/in/set-72157608801023873/</a>



But these air lines are tiny and I currently have three that are clogged. I can tell they are clogged because most of the system works great, but these three radiators only heat if I open the union near the floor on the air line. Then the radiators heat up and I get steam out of the radiator end of the open pipe. So I surmise that somewhere below the union I have a clog.



I've read all kinds of manuals and books on this system (thanks again for sharing them last year). One idea that I had: All three misbehaving radiators have no steam traps. I gather that in 1906 they used a restrictor in the air return line as a kind of half-hearted steam trap and that these restrictors often clog. (Dan's books explains how to clean them.) I thought that clearing a blocked restrictor might save me but I can't find any restrictors when I take apart the air line. Thinking about it, I doubt the restrictor is below the union anyway... the patent and manuals say it should be next to the radiator, not near the floor. I can't find any restrictors at all and when I poke my (pinky) finger in the pipe it sure doesn't seem restricted. So I think I struck out there.



I have two contractors. One hates the air lines. He wants to rip the air lines out and put on ordinary radiator vents. I really hate to do this as system works very well on the other lines and I really like the basement venting. The other contractor will hear my plea to make the air lines work but his suggested solution is to re-pipe the air lines with larger pipe (to prevent future clogs). To my mind this is only really feasible with ONE of the three misbehaving radiators. The other two are positioned such that getting to that line looks like it would require major, major work, and replacing the line would require a lot of pipe. He tried blowing a little compressed air into the line at the union but we both agreed that this is just as likely to "move the crud around" as to fix anything. Indeed, it did not work.



Does anyone have any advice for ways I can save my system and restore it to its former glory? I am hoping you have ideas! I've looked around the web and this board for more information about these air return lines but I guess they are rare.



Hoping, hoping, hoping!

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,566
    blowing out the lines

    can you take the line apart at the rad, and close to the boiler; and connect a compressor firmly to the copper air lines? maybe a little vinegar would loosen up the crud. alternatively, you could connect a garden hose to the line, and keep the pressure on until you have clear flow. if this doesn't work, could a small dia. wire be put through the pipe to clear it out?

    make sure there is some sort of filter on the end, to keep dust and dirt out of the pipe [when it goes into vacuum].

    keeping your steam pressure low, and your steam dry, will help keep those lines clear.--nbc
  • LarryC
    LarryC Member Posts: 331
    Can you remove union on airline?

    "I gather that in 1906 they used a restrictor in the air return line as a kind of half-hearted steam trap and that these restrictor's often clog. (Dan's books explains how to clean them.) I thought that clearing a blocked restrictor might save me but I can't find any restrictors when I take apart the air line. Thinking about it, I doubt the restrictor is below the union anyway... the patent and manuals say it should be next to the radiator, not near the floor. I can't find any restrictors at all and when I poke my (pinkie) finger in the pipe it sure doesn't seem restricted. So I think I struck out there."

    Home owner here with two ideas.

    First:  Disassemble airline union and carefully remove all of the airline between the union and radiator.  Visually inspect the inside of the tubing to see if you can locate the clog or restrictor if it still exists.  The restrictor might be an orifice plate captured between the vertical pipe and the elbow going into the radiator.  The elbow into the radiator might also be clogged.  Check for that.  Once the tubing is apart, if it is crudded up, then you should be able to clean it with the vinegar solution as previously suggested.



    The second idea is to verify that the air vent path to the basement is open.  Removing the mating half of the union from the radiator air tubing.  Connect a low pressure/vacuum gauge to the union and reconnect it back to the other half of the union still connected to the central air venting system.  After turning off the steam supply to the radiator, fire up the system.  See if the gauge registers any vacuum or a low pressure.  If it does, that means you have some sort of path back to the basement.



    Good Luck.



    Larry C
  • niftyc_2
    niftyc_2 Member Posts: 34
    aaarrgh

    Okay the comment about the elbow etc. -- I think that a blocked restrictor can't be the problem because when I open the union in the air return line at the floor the radiators work.  So the blockage must be below the floor.  So I think the restrictor stuff was a dead end.

    One of the three blocked air return lines is going to be a real bear to track down.  I don't think that putting a compressor on it is going to solve things because I already tried that.   It is a 3rd floor radiator.  There are two other radiators on the 3rd floor and they work.  The network of (extremely tiny) air return lines is extensive and the blockage is nowhere near what I guess is the air return "main" in the basement (this pipe is also very small but it is not as small as the lines to each radiator.  I'll ask the contractor if he has any ideas but both of my contractors hate these tiny air lines and always say to get rid of them -- a big job in the third floor.

    If you have any strategies that relate to clearing blocked air return lines that run horizontally in the floor I would love to hear them!

    Christian
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,566
    unblocking air line

    what about pressurizing it from the basement, to blow it backwards, and up? maybe a garden hose would do the trick.--nbc
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