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steam condensate

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New installation. Dry condensate main is at a higher elevation then the steam main. Will the steam pressure push the condensate thru the F & T trap into the dry condensate line. Steam trap has isolation and strainer on the inlet, check valve and isolation valve on the outlet. Steam trap inlet is connected to a drip leg.

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  • Jamie Hall
    Jamie Hall Member Posts: 23,419
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    Maybe I'm missing something, but if there is a drip leg on the inlet to the trap, why would condensate manage to get into the trap in the first place? And if so, why not use a simple thermostatic crossover trap instead of a F&T?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,607
    edited February 2017
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    The return should be lower than the main. I am assuming this is an end of main drip.

    But..........If the return must be higher..........

    Yes, steam pressure will lift the condensate but how high are you lifting it? 14" of lift requires 1/2psi.

    At the end of the main drop down , dirt leg, valve, strainer (if you want) into the trap. On the trap outlet, union immediately at trap, space nipple, check valve, space nipple and 90 degree elbow up (you wont to hit the check valve and rise up as soon as possible into the return). If possible it is better to rise up with the riser and elbow down into the top of the return
  • MikeDurigon
    MikeDurigon Member Posts: 33
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    the lift is approx 24". on the outlet of the trap i have used 2 1/2 nipples. The assembly out of the trap is horizontal nipple, EX 90, nipple, check valve, nipple, union, nipple, isolation valve, nipple, EX 90 then vertical lift of 24" horizontal 36" then drop down into top of condensate main. My thought was to put the union between the check and isolation valve to allow drain of condensate trapped in drop for future service ?


  • MikeDurigon
    MikeDurigon Member Posts: 33
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    limited steam experience more experience with hydronic systems. This system is for building humidification with the use of a Wiel McClain 980 steam boiler.
  • ttekushan_3
    ttekushan_3 Member Posts: 958
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    That shows up pretty often where there's a vacuum return -or- where the pressure is set at 5psi or so (or more) and the system is run under pressure all the time.

    That arrangemt make for noisy starups but is moot point if there is a vac return or a constant and high enough steam pressure available. I don't care for the arrangement but sometimes a properly pitched return main finds itself above a properly pitched supply main where distances are long.
    terry
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,607
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    I agree with @ttekushan not the ideal set up but it will work fine.

    The idea is to come out of the trap with the check valve as close to the trap as reasonable and after the check valve 90 up as soon as possible. Just try and keep the horizontal coming out of the trap as short as possible
  • MikeDurigon
    MikeDurigon Member Posts: 33
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    curious as to why 90 up as soon as possible. Is it that the hot condensate could cause water hammer or flash in any fluid left in behind the check valve. Would the vertical leg not have condensate in it after the steam trap opened and closed. Distance on the steam main/ condensate run is at 180 feet. Steam main is pitched down away from mechanical room with the condensate pitched into mechanical room. Interference with structure and other trades left me with zero options as far as elevation of the steam/condensate mains. Did install a steam trap at the midway point and at the end of the main as well as at the risers to the AHU. Do appreciate sharing your knowledge. Thank you Mike D
  • Steamhead
    Steamhead Member Posts: 16,887
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    If possible, I'd drip the main into a wet return.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,607
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    When the trap opens the steam pressure will push the condensate up. You want as little condensate to push at one time as possible. The rise is the rise can't do anything about that. so keep the horizontal to a minimum.

    I did a clothing factory with 50 machines that use high pressure steam (100psi). All the machines sat on the floor with traps and check valves about 2' off the floor. The condensate return line was 15' above the machines.

    It worked fine and was completely quiet. All you can here is the check valves clicking when the traps open and close
    EzzyT
  • MikeDurigon
    MikeDurigon Member Posts: 33
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    I have approx 10 more steam traps to pipe and will follow your advice to keeping the horizontal out of the steam trap to a minimum. Thank you.