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Question on the steam main

Lou S.
Lou S. Member Posts: 8
Never seen this type of steam main set up so please enlighten me. Steam main split at ceiling, goes left and right. The right side circles most of the basement and returns to above the boiler (insulated white piping) The left side of the split circles just in the boiler room/laundry room and ties back into the left steam main mid way about 5 ft before boiler, creating somewhat of a "loop" on the left side. 2 pipe system 2 story house. Replaced old leaking boiler. My question is: What is with this loop on the left steam main, and both the return and the "steam end of main" drops straight down and ties into return right b4 the hartford loop.Do I need to "Trap" that insulated steam main at the end or leave it be? The old hartford loop (not original) had a check valve on the horizontal inches b4 the hartford loop.Fired up boiler today and skimmed and it seemed to run fine but im baffled about why the left side is piped like a "loop" Thanks for your help..


  • Lou S.
    Lou S. Member Posts: 8
    This pic shows the two "returns" at boiler with original check valve
    EBEBRATT-Ed Member Posts: 13,847
    I am not seeing anything wrong with the piping in the pictures, but can't see everything
  • Jamie Hall
    Jamie Hall Member Posts: 21,568
    edited October 2021
    OK... That's a bit weird. But -- since it is tieing into the steam riser, and not the return, I don't see that there's a problem.

    So long as the connection between the drip from the steam mains and the drip from the return tie together below the water line, that's OK too..

    I see a vent on the return just before it drops. That vent is very critical to the operation of the system, and it may not be big enough.

    Now there is a potential problem, however. You say that that longer steam main forms a complete loop. Are there any vents or crossover traps anywhere on it? If not, that system is asking for all the main venting to take place through the radiators and radiator traps. Two things: this is asking a lot of those traps -- particularly if the inlets have orifices or calibrated valves -- and furthermore that vent on the return is then way too small.

    But no, you don't need to have a trap to separate the short loop at one end from the main. Nor, for that matter, do you need a check valve anywhere on the wet return. In fact, you don't want one.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Lou S.
    Lou S. Member Posts: 8
    Yes the steam and return "tie" together below the water line. The longer steam main does not "loop" it circles the basement and ends right above boiler as seen in middle picture. The shorter left side steam main heads left 10 ft, then left 10 ft then left again and ties into the middle of the returning right side steam main (weird to me)?? No "crossovers" were found but I did discover alot of the steam main insulation above the drop in ceiling had the insulation removed. We will insulate monday. Ill try to get a pic of this weird short loop on monday..