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  1. #1
    Join Date
    Dec 2015
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    Trane Voyager Scroll (CSHD) Oil Level

    Looking at what appear to be a properly functioning Voyager, the oil sight glass are always a sea of foam in the running compressor(s) at least the eight 30-40 ton RTUs I work on. Is this the experience of other techs? Trane's documentation just says oil level must be visible in running compressors and for a few minutes after.

    I'm worried about flood back in my machines, as I've lost a few compressors over the past couple years mostly to mechanical failure. I see crankcase heaters go bad often, and I had another machine that dropped its evap fan speed worryingly low after the differential pressure switch failed. Now I'm hunting for warning signs and other potential causes of flooding as I'm pretty sure loss of lubrication is killing these scrolls.

  2. #2
    Join Date
    Nov 2011
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    if you have foam, you're flooding back.

    I would adjust my superheats to around 20* at the evap.

    check with one compressor per circuit, then check with next stage, then next stage, then check that same circuit with the other circuit running.....adjust the lowest SH to around 20*, and let the high be what it is.

    the only caveat to this method is to watch your return gas temp. I think max for those compressors is about 65*. also, I believe you're supposed to check oil level after running 100% loaded for around 20 minutes, then shut down, let settle, and oil level should be around half glass.

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  4. #3
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    Dec 2015
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    Thread Starter
    That's disappointing, I'd half convinced myself these scrolls just churned up the oil into a foam when running. I think I'll focus first on making sure there isn't aren't air flow problems I'm missing before I touch the TXV. I'll remember your suggestions as I check out the machines.

    Getting accurate readings is tricky with my Voyagers as they don't run fully loaded for any extended stretch. I could put them in test or drop the discharge temp to get both stages going, but I'll soon have VAVs closing up all around the buildings. I might not have a choice except to lower all the zone temps while I'm testing, but I know the staff won't like that.

  5. #4
    Join Date
    Aug 2002
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    Southold, NY
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    20 - 40 F SH at the pump

    A few bubbles on top of the oil is normal, foaming is not.

    is the oil sump hot or cool / cold?

  6. #5
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    Dec 2015
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    Thread Starter
    The particular unit I'm looking at has pretty low superheat 6-8F. I'm reading temp just after evaporator and pressure at suction line before teeing to the compressors.

    The compressor sump is cool/sweating. The evaporator coil could use cleaning but it isn't filthy. New filters and evaporator fan belt. The unit was last charged to factory weight.

    I am worried about the possibility of airflow issues out of my immediate control: duct sizing, etc.

  7. #6
    Join Date
    Nov 2011
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    Straighten out all your airflow problems, clean all the coils, put in new filters, THEN adjust TXVs.


    Sent from my iPhone using Tapatalk

  8. #7
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    Nov 2011
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    Also, if anyone complains, tell them its a necessary step to prevent complete failure and no AC in the building.


    Sent from my iPhone using Tapatalk

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