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Steam Stumper

Randy_25 Member Posts: 21
The wet return is below the water line, I did install flush valves in both returns and flushed with water, but the water was under pressure. I'm thinking that the small return is not blocked but is restricted with crud. Does this make sense ? I was thinking of using a snake to clean the return, but would have to break it apart at every elbow. So I'm planning on replacing the returns in the spring. There was never any way of flushing the returns when it was installed in 1947.


  • Randy_25
    Randy_25 Member Posts: 21
    Two Pipe

    I have a two pipe system which is dripped into the wet return, with no traps, all convectors, no rads. There is Gorton air vents on all convectors. The boiler has been replaced it is a SGO 3 W/M. The header is 3 inch black pipe. The mains are 1 1/2 black pipe, all mains and header is insulated. The long main is 34 feet with a Gorton # 2 vent, the short main is 24 feet with a Groton # 1 vent. The wet return is 1 inch. I know that all main piping charts show 2 inch mains, but the mains are 1 1/2. The boiler will come on and run, it will cycle off on pressure before the stat cycles it off on temp. During the heat cycle it heats ok, but when it does cycle off on temp, about 20 seconds to a minute it sucks air in thru the Groton # 1 on the short run. I know that the sizes are a stumper because all piping charts show 2 inch mains. This house is not the only one like this, there are four houses that have the same setup, but with the old boiler that is about six foot tall. What could be causing the vacuum? I have flushed the returns, and have Hydro- Solv 9150 in the system to clean it up. I am planning to replace all the wet return piping in the spring. It seems that the near boiler piping is correct as per W/M specs. And it does not look like it is making wet steam. Any thoughts? I have been in this trade for 24 years and still learning. Also the pressure is set at 1 1/2 psig. Thank's
  • don_185
    don_185 Member Posts: 312
    Have you

    check the main to see if its pitch properly.Sag in the pipe
    can cause unwanted vacuum.

    Get any hammering noise?
  • Randy_25
    Randy_25 Member Posts: 21

    Don, the mains are pitched ok and no sags, and there is no hammering at all, this was installed in 1947. I'm pulling my hair out trying to figure this out.
  • heatguy
    heatguy Member Posts: 102

    check your returns and make sure if they come together that they do so below your new water line
  • don_185
    don_185 Member Posts: 312
    I'm with

    Randy on your next appoach.Sure sounds like the loop seal are running dry.

    May I suggest a vaporstat for that system.

  • Randy_25
    Randy_25 Member Posts: 21

    Yes I did install a vapor stat and the boiler really short cycled, the boiler is oversized by 32 EDR, someone removed a convector, which I'm in the process of reinstalling.
  • Randy, I've seen a few of these in Baltimore

    Also check to see if the wet return is really "wet" through its entire length. The SGO has a much lower water line than the typical 1947-vintage model. If any of the convector drip connections to the wet return are above the SGO's water line, you'll have air coming at the convectors from both sides and they'll never heat well.

    If you find this problem, the cure is a False Water Line as shown in "The Lost Art of Steam Heating". Or, if you replace the return, run the new one as close to floor level as possible.

    The 1-1/2-inch steam mains should not be a problem if the system is small. Despite the sizing charts that say 2-inch should be the smallest size, I've seen plenty of 1-1/2-inch ones that work fine as long as they are parallel-flow.

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  • ttekushan_3
    ttekushan_3 Member Posts: 958

    Is there a brand name on any of the convectors? What is the brand name on the neighbors' boilers (assuming they're original)? Do the neighbors also have vents on the convectors and mains?

    Convectors and unit heaters can develop a tremendous amount of vacuum and it must allowed to "break" at some point.

    From the pipe sizing and the fact that convectors are used I have a hunch that this may not be an ultra low pressure system. I understand the desire to turn down the pressure, but some systems were never designed that way.

    At the risk of being ostracized, try turning the pressure up, to say 3 lbs, diff 1, or 3.5 lbs diff 1.5 and observe what happens. Does the distribution of condensate change the dynamic such that where the vacuum is pulled changes?

    The reason I mention this is that as with the "ancient" two pipe with vent, the returns were expected to be filled with steam and water. The vent on the rad/convector takes care of the air so they should heat if even fed back from steam in the return system.

    A perfect example of the last generation of residential steam heat in the post war era is the Select Temp system. Notice the boiler and unconventional arrangements. This was a higher pressure system that lacked individual venting as originally installed but with a pressure powered pump (from heatinghelp's very own Library):
  • Randy_25
    Randy_25 Member Posts: 21

    The convectors are a combination of Beacon Morris and Trane, I found them in Dan's EDR book and found what the EDR value is for them. I will have to check the other systems to see what the boiler is. All of them is setup the same, vents on the convectors, and main vents at the ends of both mains. Pipe size is the same as well. They are not the Trane vapor system.
  • Randy_25
    Randy_25 Member Posts: 21

    These systems are in Carroll County which is not that far from Baltimore. This is what I love about this trade, you seem to never see it all, and learning is everyday.
  • Randy, if you wish

    I can come up and consult on them. The ones I've seen are in the Hamilton neighborhood of Baltimore. E-mail me on [email protected] or call our office, 410-321-8116.

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  • john_27
    john_27 Member Posts: 195

    For what it's worth, Steamhead and his company are the "Doctor's Doctor" of steam companies....they get the jobs no one else can understand, and get them right. And, they are very fair on pricing. They did work on an old Broomell system in Philaldelphia that had the locals completely stumped.
    Very impressive guys.
  • gerry gill
    gerry gill Member Posts: 3,078
    Randy, whats the problem?

    the fact that the gorton #1 sucks air in when the boilers goes off on limit? there is 1 1/2 pounds of compressed steam in the pipes..its suddenly collapsing into a vacuum..why is there surprise that the air vent is opening to break the vacuum..if its anoying, put a vacuum vent there..but its gonna break that vacuum from somewhere else then..sorry, i fail to see the issue..what happens when you downfire the boiler?

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