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Strange steam "equalizer"

Hi all -

I saw something in the field that I can't figure out.  The system is a one-pipe steam system with a wet return that runs along the floor.  The boiler is a Weil 1188 (bout 3,000 MBH).  As you can see in the attached simplified sketch, there is a 1" "equalizer" line that connects from the side of the steam header (so it takes steam, not condensate) to the wet return.  (This is in addition to the normal equalizer line and Hartford Loop.)  There is a big (1-1/2") trap just below this 1" line, and the trap dumps to the boiler feed tank, which pumps into the boiler.  It is the only trap in the system, and it is below the boiler's water line.  I can't see what this 1" line is for, unless it is to allow the boiler to run at a pressure above 1 psi - i.e., to prevent boiler pressure from pushing through the return, through the feed tank, and out the feed tank vent.   Any ideas?  When the boiler is replaced, do we keep the 1" equalizer and trap, or eliminate them?



  • Dave in QCA
    Dave in QCA Member Posts: 1,777
    Alternating Receiver, perhaps?

    A picture would do wonders here...    It sounds like some of the old equipment was not removed when an older boiler was replaced with a boiler and a condensate receiver.

    An Alternating Receiver does the same job as the receiver tank, without the need of a pump to put the water back in the boiler.  There should be 4 connections, or perhaps 3, if the condensade line coming in and the boiler feed lines are fitted with  check valves.  The 2 top connections consist of 1 vent and 1 steam connection.  The bottom connection is for condensate.  As the condensate comes back from the system, it rises through the bottom port into the body of the receiver.  Air is exhausted throug the vent, the steam connection is closed.  As the the receiver fills, a float mechanism causes the vent to close and the steam connection to open.  Now the receiver is at the same pressure as the boiler, and since it is at a higher elevation than the boiler, the condensate runs out, and into the boiler.  Check valves prevent the condensate from flowing backward to the system, and also prevent the boiler water from flowing backward into the receiver when the receiver is at atmospheric pressure.  

    Look at the low pressure diagram on page 2 of the Sarco Alternating Receiver brochure.  I found it posted on this fantasic site!  Here is the link,  http://www.heatinghelp.com/files/articles/1323/58.pdf 

    Not sure if this is what you have going on, but it sure sounds like it.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • gerry gill
    gerry gill Member Posts: 3,058
    if the wet return bypasses the feed tank

    as the drawing suggests, when its time to do some replacement or repiping i would just install an equalized reservoir tank in the wet return to hold extra water for the boiler, and thats only if it was found that there wasn;t enough water for the steaming process..in the current configuration the line you question makes no sense to me either..
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Steamhead
    Steamhead Member Posts: 15,988
    edited June 2010
    Is the trap

    higher than the boiler's water line?

    If so, what you have is a False Water Line. It is designed to keep the standing water in the wet returns higher than the boiler, so water will fill the returns up to a point and keep steam from going places it shouldn't. The waterline of the existing boiler is probably lower than that of the original, and the FWL makes up the difference.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,253
    Gary was this near Boston?

    Seems to be a few "old" steam guys adding those traps out there. They say they need them when they add the pumps to keep the system from banging and the receiver tank from flooding. I think they need new returns and the3y are doing this to postpone changing out the half clogged returns. But since it "works: no one wants to fix it.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Gary Elovitz
    Gary Elovitz Member Posts: 14

    Thanks for all of the input.  The building is near Boston, and the trap is below the water-line.  I'm still scratching my head, but I appreciate all of your suggestions.
This discussion has been closed.