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Steam headers

What is the purpose of rising up 24" above the water line on a steam boiler?

Also, is there any alternitive if you dont' have height to get the 24" rise?


  • Jamie Hall
    Jamie Hall Member Posts: 18,907
    There is a very good reason...

    When steam is made in a boiler, it doesn't just come off the top nice and peaceful like, but in bubbles -- big bubbles -- from the heated surfaces.  Which come to the top and burst -- and carry a lot of water droplets around.  It then moves up the risers at speed (which is why you want at least as many, and at least as big, risers as the installation manual directs).  The objective of the 24 inches is to let as many of these water droplets as possible drop back into the boiler before they get into the header and the rest of the system, causing "wet" steam which creates a variety of problems, from water hammer to low efficiency.

    There really isn't a good substitute for the distance, but on the other hand it isn't a hard and fast cutoff.  A dropped header arrangement will help dry the steam -- but if you are short on the rise, you will still have possible problems with wet steam.  A much larger dropped header than normal will help much more (for instance, use say a six inch where you would normally use a three, etc.).  It still won't help the efficiency problems which arise from wet steam, though.

    You might repost this over on the strictly steam board, if you haven't already.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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