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Better without main vent???

I went to a customer a few days for some routine repairs. While there I noticed that most of the one pipe steam radiators(regular old fashioned cast iron radiators) had been repiped with 3/4" copper. The puzzling thing is that they didn't bang or spit water as I would have expected them too. With pipes that small I would have thought that the incoming steam would move too fast for the condensate to return. The only conclusion that I can imagine is that the steam is moving slowly enough through the main that even the increase of speed inside the 3/4" pipes is too slow to hold back condensate. The boiler appears to be piped correctly and the water level seems adequately stable. I cant tell if there are main vents(basement is finished). I would have to assume that there are no main vents(most places don't have main vents anyway). In this instance I would think that it might be better to advise the customer NOT to install main vents. Weird!


  • Ban
    Ban Member Posts: 79

    Sounds like a system with a lot of problems.
    Richard Ban
    Detroit, Michigan (Dunham 2-pipe vacuum)
    STEAM DOCTOR Member Posts: 1,927

    Funny thing is that the system seemed to be running fairly smoothly
  • jumper
    jumper Member Posts: 2,206
    was the building renovated ?

    If the building is much tighter & better insulated than it originally was, then there's less condensate and steam demand.
  • Jamie Hall
    Jamie Hall Member Posts: 22,877

    Usually I'd be pretty adamant about restoration and improvements, like main vents.  However... is the heat reasonably even?  Is it quiet?  Does the boiler do the job without much if any cycling on and off?

    If so... my other mantra is "If it ain't broke, don't fix it"
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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