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short cycle?

Dan_43 Member Posts: 53
I have a 5 year old boiler

The pressuretroler is set, off at 1.5 on at .5 lbs.  and it does so with precision but is seems to loose the pound in about a minute.  I am not loosing any water, I may have to add a little water once every 2 weeks.  Is this right?  our some of my vents blowing out to much steam before they shut off? What do you all think?

Have a Steamy New Year!



  • vent blowing steam

    the vents should close completely when steam arrives at their location, so if not, are they mounted up a foot or so from the line? is your pressure right-under 22 ounces? they may just need replacement. when replacing them, consider getting the maximum number you can install on each location. while you are twirling the wrench, get a good  0-3 psi gauge, so you know whats up. the quick loss of pressure when the boiler cycles is normal, as the steam quickly condenses, and is replaced by a vacuum. assuming that the boiler is not oversized, the proper amount of venting will reduce the number of cycles as the thermostat is calling for heat, by letting the air out at very low back-pressure. tell us what your present vents are and the pipe size, and we can further advise.--nbc
  • Dan_43
    Dan_43 Member Posts: 53

    What do you mean, "are they mounted up a foot or so from the line?"  are you talking about my venting on the returns at the boiler, if so they are up about a 1' high and in a tree with 3 vents on each.   (2nd question) Are you asking about the size of pipe going into the radiator and the radiator vents? Or the vents at the boiler?

  • Jamie Hall
    Jamie Hall Member Posts: 23,270
    Sounds about right

    The losing a pound in a minute or so.  What is happening is the steam is condensing, not leaking, and that will drop your pressure remarkably quickly.  It's supposed to do that.

    I presume that this is all happening towards the end of a heating cycle, when things are pretty well satisfied.  If this assumption is correct, then what you are seeing is reasonably normal (given the variety of steam systems, "normal" can be a little hard to pin down!).

    A vent should shut off.  However, this does not mean a vent shuts instantly when steam hits it.  Some take longer than others!  A short (define short.  Right...) wisp of steam when it first hits is probably quite normal.  If it keeps on leaking (doesn't seem so, from you description), then you may have a problem.

    A little water once every couple of weeks doesn't sound like a problem either -- but then, in my setup, I'd never notice it, as I blow the LWCOs down every couple of weeks anyway!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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