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trane vapor system

cm Member Posts: 2
Need some help. I have a trane vapor system that we replaced the boiler on, and we're having a problem with short cycling. At the end of the steam main was a 1/2 inch trap, it was definitely bad letting steam through. when I removed it I noticed it was an original trane DRIP TRAP. We installed a thermostatic trap in its place but now water will not return to the boiler. Did we use the right trap?


  • Jamie Hall
    Jamie Hall Member Posts: 22,918
    Where does it go?

    Presumably one end of the trap is connected to the steam main.  Where does the other end connect?  Dry return?  Wet return?  If it's the wet return, it may not be needed.  If it's the dry return, then it should be OK.

    Can you take a picture or two, or draw a diagram?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • cm
    cm Member Posts: 2

    Sorry, the outlet is piped into a 3/4 line that drops into the wet return
  • MotownSteamer
    MotownSteamer Member Posts: 110
    edited November 2011
    those are probably crossover traps

    I have a Trane vapor system too. I replaced the main vent at the same time as the crossover traps and radiator traps. How is the main vent on your system? If the cross over vents are putting now air into the return, but it can't get out through the main vent, it might be locking up the condensate.

    Also, does this system have a Direct Return Trap? If so, there is a PDF we can link you to that explains how they work. If this system has one, and it's not working, it might be part of the problem too.
  • Jamie Hall
    Jamie Hall Member Posts: 22,918
    OK, next question...

    This baby goes into a wet return, right?  The next question is -- is it piped off the top or the bottom of the steam main?  If it's off the top, it almost certainly is a form of crossover trap -- although the other end of those is usually piped into a dry return (which is vented usually at the boiler).

    If it's off the bottom, it's a condensate drip -- but if it goes into a wet return, it's not needed.  In fact, when it's closed it will prevent the condensate in that return from "feeling" the boiler pressure, which could cause condensate to hang up in that wet return and not come back to the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,726
    Not always

    Some Vapor systems had non-pressurized wet returns, where everything went thru a trap before entering the return line and everything went thru a Return Trap on its way back to the boiler. Webster systems used this configuration most, but Trane and others did too sometimes.

    We'd need to know how these things were originally connected, whether there is a Return Trap and if both the dry and wet returns are routed thru the Return Trap.

    Where are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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