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Steam in my returns?

I think I have steam in my returns. Background-two pipe vapor, gas fired boiler. This fall I replaced all the radiator traps, two cross over traps, and a new main vent. I've cycled the system the last three evenings and over all, everything is great. All the radiators are toasty and quiet. We make steam about 15 minutes in. The issue is, after we are all steamed up and pressure starts to build, the returns get hot. Not warm, hot. The cross over pipe is not hot, it's warm. No problems with the radiators (they stay warm), but then again I've only been running the system for about 45 minutes to an hour. Oh, and once we start pressurizing (cut out at 1 lb) the system short cycles. I know I likely have too much pressure for this system, but could that be causing this? What is the likelihood I have a bad, brand new radiator trap? Or do I not have a problem? "Lost Art" mentions returns getting hot after the mains.......help!


  • gerry gill
    gerry gill Member Posts: 3,078
    its blowing past a trap someplace.

    boiler may also need to be downfired if all radiators are hot all the way across and you still have 'extra' steam..
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • moneypitfeeder
    moneypitfeeder Member Posts: 249
    I'm lost

    Which returns? Directly from the radiator? After the crossover? Where exactly is it getting hot?

    Also with the short cycling, does your boiler match the connected radiation? Or is it oversized? Another thing that could cause short cycling could be as simple as a thermostat setting.

    What traps did you originally have, and what did you replace them with.

    And yes as you know, you need to get that pressure down
    steam newbie
  • MotownSteamer
    MotownSteamer Member Posts: 110
    all the return piping in the

    basement gets hot. The crossover pipes are not, so the end-of-main traps are good . I think Gerry is right, I have a radiator trap being naughty somewhere. That is aggravating since they are all new! I hope we are not damaging the others? Anyway , yes.....the current boiler is way oversized which is one reason why I've contracted for a replacement. As to the short cycling, yeah....I've arbitrarily jammed the thermostat up to 70 or more just to start the boiler, so that is likely the problem there. I'm not too worried about that stuff in lieu of the new boiler(two more weeks). We'll just bump her on durning chilly nights for 45 minutes or so......unless this bad trap business could cause a catastrophe?
  • Steamhead
    Steamhead Member Posts: 16,729
    Follow the heat

    back to the radiators. When you find a return runout that is steam-hot, that's where the bad trap is. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • MotownSteamer
    MotownSteamer Member Posts: 110
    in other words

    I'll feel the return pipe on the downstream side of each trap, right? Or do I need a temp. sensor?
  • gerry gill
    gerry gill Member Posts: 3,078
    yes, downstream

    side of each trap.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • MotownSteamer
    MotownSteamer Member Posts: 110
    Just a thought.....

    "Lost Art" mentions high pressure in a vapor system can mimic trap failure. Really hot condensate can flash in the return pipes because the higher boiler pressure is making hotter water, steam ,etc. Now, I've got the pressurtrol down to cut in at .5 an out at 1. But, if a vapor system should be pressured at only a few onces, I could have a pressure issue? The snapping DRT and really, really warm radiators would seem to point in this direction. I think I'll get a vaporstat on the system pronto, but I will check some traps too.
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