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One Pipe Steam Heat system and replacing the return in the basement

Over the years the house has settled and the return in the basement doesn't drain well. There are all kinds of repairs to the pipe because of it and I am considering replacing the whole run in the basement and correct the drainage/flow to the boiler. What would be the best type of pipe to use? My experience is the black pipe didn't hold up well.


  • JohnNY
    JohnNY Member Posts: 3,231
    I confess I use copper L tubing on wet returns.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
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  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Copper seems to be fine for wet returns.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ethicalpaul
    ethicalpaul Member Posts: 5,704
    edited January 2022
    Over the years the house has settled and the return in the basement doesn't drain well.

    There is an error in your statement here. Settling cannot harm the return unless it forces some of it above the boiler's water line. A return does not have to pitch toward the boiler. It can be level, or it can even run uphill to the boiler as long as the entire wet return remains below that boiler water line.

    Of course, sediment will collect in any low spots so you don't want it to be ridiculous, or if it is a little ridiculous, you at least want some tees and valves available to flush part or all of it.

    I made mine with black pipe because it's only about 8 feet long, but if/when that ever fails/rusts out I'm 100% going to replace it with pex. I'm not even kidding.

    Finally, it has been my observation that people are very very quick to blame the return for things that are actually caused by poor near-boiler piping. If you care to describe your symptoms, it would be interesting to hear what you're dealing with.

    Edit: @JUGHNE has a great response below. My post is assuming wet return
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    JUGHNE Member Posts: 11,062
    Is this return line lying on or just above the floor but under the boiler water line as you see it in the sight glass?

    Or is it hanging from the ceiling and all above the water line.
    If this is the case then the steam main piping may have suffered loss of slope from house settling.

    Pictures of the piping system are needed to clarify the problem.