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Should a steam trap be closed at this temperature?

ariccio
ariccio Member Posts: 67
in Strictly Steam
PXL_20241206_225847470.jpg

I haven't been able to hear the sounds of the trap opening opening and closing with my stethoscope.

For the past several months, I've very rarely seen it reach atmospheric steam temperature, but this is a vacuum steam system, so for all I know there's slightly subatmospheric steam in the pipes. I know thermostatic traps are mechanically intelligent enough to close at differing temperatures depending on the pressure in the system… but how can I tell if it's supposed to be closing?

I kinda suspect there's some but just not much steam entering this radiator, since it's 35°F out and the radiator is way above ambient, but I don't know what to make of a 3ish degree temperature drop across the trap. I wouldn't be surprised if a wide open trap loses a few degrees just to the radiation along the surface of a few inches of pipe.

For reference, top left is the supply into the radiator, bottom left is the outlet of the radiator, top right is the outlet of the trap, and bottom right is the room temp.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 25,209

    I suspect that it's closed. Check a foot or so further down the outlet; that should be distinctly cooler.

    Traps don't snap open and shut, but close gradually — so you may not hear a click.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    TKPK
  • ariccio
    ariccio Member Posts: 67

    I see. I was wondering if it was modulating at one end of the open/close regime. I wish I could see a curve for it or something! I'll move the hose clamp thermocouple when I pull the data next and I'll be curious to see what I find.

  • ariccio
    ariccio Member Posts: 67

    Aha! I've figured it out.

    The issue is that having multiple thermocouples on the same conductive surface is causing interference between them. Ordered some thermally conductive, electrically insulating, tape.

    delcrossv
  • ariccio
    ariccio Member Posts: 67
    12-9-2024-dining.png

    This data looks a lot better now. Had to wrap the contact points of the pipe with the thermal interface material electrically insulating tape, but then was able to confirm that there was no longer any crosstalk between the sensors by repeatedly plugging and unplugging from the meter.

    And if you're wondering, yes, it did suddenly start to get a lot hotter in this apartment around 3PM, it almost looks like someone is screwing around and bypassed the controls, since the radiators have indeed been blasting almost nonstop for twoish hours now.

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