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water return is slow

gibson Member Posts: 15
I have an oil-fired one-pipe steam system. The returns are 50 years old. After the steam boiler cycles off, it takes 10 minutes for the water level in the glass gauge to return to normal. Is this an indication of clogged or slow returns, or is this normal?


  • BobC
    BobC Member Posts: 5,408

    How far does the water in the gauge glass fall?

    My single pipe steamer drops very little (1/8 - 1/4") and returns to normal 2-3 minutes after the boiler shuts down. The boiler is 14 years old while the system is 90+, the boiler is oversized.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • gibson
    gibson Member Posts: 15
    Level drops about 1/2 inch

    If the boiler runs for 15 minutes before turning off, the water line in the gauge drops about

    1/2 inch. I wait for another 15 minutes and then check the level. Finding it low, I add some water. Then, later in the day I check it again and find that the level has become too high. My assumption is that the water in the returns drains back very slowly after I've added water. The pipes are pitched properly and the water shutoff valve is good.
  • Jamie Hall
    Jamie Hall Member Posts: 21,519
    It does sound...

    as though the returns may be partly clogged.  This isn't that unusual, really.  The problem is how to fix it.  Some systems are nicely piped so the returns can be flushed out.  Most aren't.  But there might be a handy plug or something which would allow you to flush out the return, with an equally handy valve so you didn't have to drain the boiler...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    New Hampshire DIYer
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