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Horizontal pipe in Hartford Loop

Scott216 Member Posts: 13
I just came across a great document from Peerless about one-pipe steam systems. It says that the horizontal pipe going into the Hartford loop (see picture) should be a close nipple. I just redid the piping on my boiler, and not knowing this, I used an 8" nipple. I could change this, but I thought I ask people's opinion first. I have fired up the boiler a few times since redoing the piping and there's no water hammer. Since it's still warm in NJ, the boiler has only been on for testing. Is this something that is often an issue? Anyone know why Peerless recommends a short nipple here? Their document doesn't go into the reason for this.


  • Jamie Hall
    Jamie Hall Member Posts: 19,424
    There's ideal, and there's works. If it doesn't bang, don't worry about it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JK_Brown
    JK_Brown Member Posts: 22
    You have steam in the equalizer and cooler water coming in the Hartford Loop. When these two meet, you can have rapid condensation creating a low pressure at the equalizer. This will cause water to rush into fill the void. The slug rushing through the nipple picks up speed till it slams into the tee so the close nipple limits the noise, and impact force, of the slug. Hence their advice for mid-cycle water hammer.
  • KC_Jones
    KC_Jones Member Posts: 5,113
    Just as a heads up, this isn’t Peerless only, every manufacturer says close nipple.  This is standard practice for a steam boiler, instructions or not.

    The best way is with a wye instead of a tee.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    EBEBRATT-Ed Member Posts: 12,362
    A close nipple or Y is ideal. It is where steam and water meet so to minimize water hammer the shortest connection is used.

    Like @Jamie Hall said if it doesn't hammer leave it alone
  • ChrisJ
    ChrisJ Member Posts: 13,258
    If it was mine I sure wouldn't even think about taking it apart unless it complained.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Scott216
    Scott216 Member Posts: 13
    ChrisJ said:

    If it was mine I sure wouldn't even think about taking it apart unless it complained.

    Agreed. I'll leave it alone unless there's hammering at that Tee. I've had the boiler on a few times and so far no hammering anywhere.
  • Lance
    Lance Member Posts: 217
    The best engineering advice works all the time. But many things can work some of the time. They come under my heading of "If it ain't broke don't fix it!"
    EBEBRATT-Ed Member Posts: 12,362
    If every boiler and furnace that were not installed by the book were shut down 90% of the people would freeze.