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  1. #1
    Join Date
    Mar 2014
    Location
    Pittsburgh, Pa
    Posts
    33
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    19XR low discharge superheat

    can't get oil back. Chw in 49.8/out 44.0./ Evap refr 41.8/ CDw in 77/out82.8/ cond temp 87.0 /oil press. 24.3/ temp.132.7/ amps80.9%

  2. #2
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    97
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    If your oil sump level is low and the chiller is tripping on low discharge superheat, it is likely the oil is in the evap and carrying over resulting in this fault. The cause of this condition could be an overcharge condition and also, ironically, an undercharge condition.

    The evaporators on the XRs have no eliminator screens which makes them easily suseptible to this fault.

    Carrier has a SB regarding the procedure to return the oil back to the sump, as well as the related procedure to properly charge or to confirm the proper charge of these chillers.

    You've got mail...

  3. #3
    Join Date
    Mar 2014
    Location
    Pittsburgh, Pa
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    33
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    My oil skimmer sight glass is bubbling pretty good no matter what I set the demand limiter at. Trouble is, I have a constant high load now.

  4. #4
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    97
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    When you say "demander limiter" do you mean % Amps?

    According to the SB, you should be limiting the capacity of the chiller by vane position (I usually set them to about 5%). At that point, i would see what the skimmer line SG is doing.

    If you're still seeing a good volume of foam/bubbles in the line under those conditions, i would take a look at the second SG which is in the eductor line within about a foot of the oil sump. That line too should have a good volume of foam in the glass, if not, you may have a plugged strainer (the discharge line which "powers" the eductor) OR the oil return line from the bottom of the suction cover which has a soldered sock style fine mesh strainer on the inside of that fitting, may be plugged. I have seen that plug up quite a bit.

    Let us know what you find.

  5. #5
    Join Date
    Mar 2014
    Location
    Pittsburgh, Pa
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    33
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    I didn't see any activity in the upper glass. Just half full of oil that looks like it's just sitting there. Thanks. I'll let u know.

  6. #6
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    97
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    Any updates cals8?

  7. #7
    Join Date
    Mar 2014
    Location
    Pittsburgh, Pa
    Posts
    33
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    just got back at it today. I was told by the previous tech that I have to run it up to about 80% ,while watching discharge superheat, to get the oil back because they ran it too long in low load conditions. Running. I'll let u know

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