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Steam Pipe Insulation per Code Requirements

PaulVW Member Posts: 2
In 1 of the cities I service, the city is requiring all new pipes on replacement steam boilers to be insulated even if none of the other pipes are insulated. I understand the value of insulating steam pipes but I believe I read or heard in one of the Don H seminars that it was a bad idea to insulate the wet return on a 1-pipe steam system. As I remember the condensate needs to lose some heat before it gets to the close nipple of the Hartford loop to reduce flash steam and banging. I looked through “Lost Art of Steam” and could not find it. (I do need to buy a new book, it was bought in 1993 and is quite worn...) Please let me know if I’m on the right track, I have to document it for the inspector.


  • Jamie Hall
    Jamie Hall Member Posts: 16,534
    The condensate in the wet returns should not be that hot in the first place -- one pipe or two pipe. Further, the pressure at the Hartford loop -- applied by the equalizer -- should be high enough to prevent any possibility of flashing.

    In my opinion and understanding, anyway...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 15,368
    Paul, I believe condensate returns and better off insulated. As water cools, it absorbs carbon dioxide, which results in carbonic acid that rots pipes.
    Retired and loving it.
  • ChrisJ
    ChrisJ Member Posts: 11,831
    My wet return runs much hotter now that I insulated the dry returns especially when it's very cold out. Not sure how hot, but too hot to touch.

    I wish I could insulate the wet return, but it's placement makes it kind of difficult if not impossible.
    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