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Feedwater P-Trap at Hartford Loop Connection???

Zoso Member Posts: 33
I am replacing a low pressure steam boiler (15 psi relief) that has pumped condensate returning into the Hartford loop just below water line. So far so good. However, there is a P-trap type arrangement right at the point of connection to the Hartford loop (see photo). What is the point of this? I'm guessing nothing. The pump is across the room underneath the boiler feed tank. It has a check valve on the discharge (not that the P-trap would hold back the pressure anyway). I have never seen this before. Any ideas?


  • AMservices
    AMservices Member Posts: 610
    Possible swing joints to help with expansion, if its mostly welded pipe. or maybe an attempt of keeping steam out of the vertical drop and making its way to the horizontal pipe full of water. 

    EBEBRATT-Ed Member Posts: 15,512
    I agree with @AMservices

    Probably trying to keep steam out of the feed water line.

    BTW @Zoso ASME code requires 2 check valves with a feed water pump 1 at the pump and 1 at the boiler
  • Zoso
    Zoso Member Posts: 33
    I'm trying to understand how that would help keep steam out of the line. The line ties in below minimum water level so there should be no Steam. With a check valve back at the pump and the boiler pressure pushing against it, the line should remain full of water. Even If gravity could somehow drain that line it would be in vacuum and immediately fill with water from the boiler. I don't know, I'm just trying to wrap my mind around how a little P-trap could keep the steam out of that line.

     I see your point about having 2 check valves. I'm not planning on putting that P-trap back in when I replace the boiler.
  • Jamie Hall
    Jamie Hall Member Posts: 23,273
    I don't see how it would keep steam out either -- if the water level dropped that far, there isn't enough depth there to accomplish much of anything.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • motoguy128
    motoguy128 Member Posts: 393
    They cut the vertical pipe too long and ran out of material to cut another one so just make it work with fittings and close nipples.
    EBEBRATT-Ed Member Posts: 15,512
    edited December 2020
    If it was me I would put the feed water into the return header at the bottom of the boiler. You don't have or need a Hartford Loop with pumped returns. Just an equalizer