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How long should a one pipe system hold its pressure?

Hi fellow steam fans and aficianados ... I've got my system operating between 0.5 and 1.5 psi. On a cold day with the system running continuously it takes about 3.5 minutes to go from the the cut in to cut out and about 1.5 minutes to cut back in. So its losing 1psi in in less than 2 minutes.

Is this typical?

I know pressure and temp move inversely and obviously with the boiler cut out temp will drop but im surprised at how quickly this happens in a system thats fully heated, so just trying to figure out if this is typical.

Tx in advance / avi


  • Steamhead
    Steamhead Member Posts: 15,508
    If there are no leaks

    then this may be normal. Remember the steam is condensing in the radiators and this will pull more steam into the rads, dropping the pressure in the process.

    But check the system for leaks first. The usual suspects are vents, radiator valve packings and underground return lines. If you have a water feeder with a built-in counter, this will help you determine if the system is losing water.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • iddelz
    iddelz Posts: 16
    No leaks

    The water in the boiler drops when the system is on continuously I think because the returns are probably a bit clogged and there's also some bad piping underneath one big radiator we installed that I know traps water. But when I reset the system within five minutes it's back to normal.

    So in short, no leaks, no whistling, banging only where that subfloor piping is faplooey. So it sounds like as normal as I'll get it without ripping up the floor.

    Thanks for the sanity check
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