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  1. #1
    Join Date
    Mar 2014
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    Pittsburgh, Pa
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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
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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
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    Pittsburgh, Pa
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    Thread Starter
    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
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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
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    Pittsburgh, Pa
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    Thread Starter
    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
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    Any updates cals8?

  7. #7
    Join Date
    Mar 2014
    Location
    Pittsburgh, Pa
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    Thread Starter
    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

  8. #8
    Join Date
    Sep 2008
    Location
    New England
    Posts
    245
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    Do you still have the bulletin for this?

    Do you still have the bulletin for this?

    Quote Originally Posted by tcy612 View Post
    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...
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten". --Benjamin Franklin

  9. #9
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    133
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    Quote Originally Posted by alliedtech12887 View Post
    Do you still have the bulletin for this?
    You got mail...

  10. #10
    Join Date
    Oct 2011
    Location
    Upstate NY
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    Quote Originally Posted by cals8 View Post
    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
    I know this was from 3 years ago but I find it incumbent upon me to set the record straight.

    What you were told about having to load the machine to return oil back to the sump IS inaccurate.

    READ the applicable manual for this chiller under the "oil return system" section,

    AND

    READ the Service Bulletin. IF you didn't understand it, READ IT AGAIN and AGAIN until you DO understand it.

  11. #11
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,841
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    I had a 19XR in my plant start tripping on low oil in the sump. It was a PITA to get the oil back, but I remember having to do it by holding the guide vanes barely cracked open and letting the machine just run like that while another chiller nearby took the building load. The oil tripping chiller apparently had a good amount of carryover of oil into the condenser. Even while trying to get it back by holding the guide vanes, the machine tripped several times until enough oil returned to keep the oil pressure transducer happy.
    Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.

  12. #12
    Join Date
    Jun 2006
    Posts
    371
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    Would you be able to share that bulletin TCY?

  13. #13
    Join Date
    Mar 2011
    Location
    Midwest
    Posts
    221
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    I would like that secret squirrel service bulletin I couldn't find it on carrier com Lit under 19XR .

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