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Steam boiler main vent question

Hey everyone,

I have 2 pipe steam.  Instead of an F&T trap the system runs the supply lines (2) back to the boiler under the boiler's waterline. Currently there is an air vent at the end of each supply line before it turns 90 degrees to go under the boiler water line.

I was cleaning up the installation of the air conditioning system and found an old 1/2" line coming off the return line.  It looks like it formerly hooked into where the air vents are on the supply side likely with some kind of steam trap.  The supply line would then use the air vent that is at the end of the return line.

The air vents on the supply side are right under the hearth of my fire place.  When they go bad they damage the hearth rather quickly until I replace them.  I would rather have them on the return line if possible like it looks like they may have been originally.  Not sure if the one vent would be fast enough but it was a thought to change it back to this.  Has anyone seen a setup like this?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,516
    Sounds like you may have found. an old crossover trap Best bet is to post pictures of the boiler the piping around the boiler and your air vents and supply & return piping and a couple of radiators
    nlongworth2
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    It does sound like the remains of a crossover. Photos will tell. There should be one on each main. Be happy you don't have an F&T. They are not needed on a properly running residential system.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    nlongworth2
  • nlongworth2
    nlongworth2 Member Posts: 11
    See images below.  Supply pipes in the back are the ones that have the air vents and are sloped back to the boiler.  Supply pipe in the front is where the steam goes into the system.  Return pipe is to the left in front of the auto feeder (vertical pipe on right is gas line).

    Another strange thing is the large radiator in our living room has an air vent and a steam trap for the return.  The radiator is about 6 ft long and knee high.  The vent is to help air get out of it faster?  It still heats (and well) so I would assume the trap is good.



  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    That radiator is interesting. The vent may indeed help it heat better; two pipe radiators are usually fed at the top at one end.

    On the rest of the system. It would help a lot -- both for you and for us -- if you clearly distinguish between steam mains, dry returns, and wet returns.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JohnNY
    JohnNY Member Posts: 3,229
    The digital counter on your water feeder strongly suggests you're losing a lot of water.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
    nlongworth2
  • nlongworth2
    nlongworth2 Member Posts: 11
    The boiler is in a tight area so it is a little hard to get a good image.  Here is a color coded one.  

    Red is the steam main
    Orange is where the steam main returns to the boiler for the crossover you have mentioned
    Blue is the dry return, all returns meet up to this single point
    Green is the wet return (again no F&T trap so steam and return lines both go into here directly)

    Two of the air vents are bad right now so I'm not surprised I am currently losing a lot of water.