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Low (no pressure) in boiler

Hello Steam Friends,

I am working to fine tune the one pipe system in our house. When the boiler cycles, it never trips the pressuretrol (which is set at .5). The 0 - 30 gauge gave up the ghost a few weeks ago so I bought a 0 - 3 lbs gauge and put on a T with the pressuretrol. When the boiler is firing, the low pressure gauge needle shows a little motion but doesn't really move off the zero (photos shows ). Then after the boiler cycles off, the gauge reads a little vacuum. Shouldn't there be more pressure showing on the gauge? (photo shows slightly below 0)?


  • Jamie Hall
    Jamie Hall Member Posts: 19,410
    What does

    cycle the boiler off?  The thermostat, I presume?  Then the question is -- does your whole system heat up the way you'd like it to?  If it does, your good to go -- pressure is not what drives a steam system, and the fact that you don't see any pressure simply means that the radiation is condensing all the steam that the boiler can deliver.  And if that's enough steam, that's great!

    By the way -- you will find that your building code and quite possibly your insurance man will require a 0 to 30 psi gauge.  You can keep the 0 to 3 gauge in addition to it, but there is that code requirement...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Jeff_44
    Jeff_44 Member Posts: 94
    edited February 2011
    For the most part

    the system is working well. The boiler cycles off with the thermostat. I have been refining the balance issues with the help of many great folks here on the wall. On occasion, there will be a random radiator that does not get heat (or less heat). And I seem to losing a little water. I've marked the site glass with a piece of tape is as time goes on, the water level drops a little - maybe a half inch in the last month. I hope there's not a hole in the boiler. I don't really see any white plumes coming out of the chimney. It was in the low 40's today and I could see a faint hint of exhaust but not a white cloud.

    There is a place on the boiler for a 0 - 30 lbs gauge - the one that came with the boiler got fried so it looks like I will need to replace it. Thanks for the tip.
  • Jamie Hall
    Jamie Hall Member Posts: 19,410
    A half inch per month

    is not, honestly, something I'd worry about.  No steam system is perfectly tight; one pipe steam systems, particularly, lose a little bit of steam each cycle through the radiator vents.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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