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Thread: Carrier 19XR

  1. #1
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    Carrier 19XR

    Having low oil pressure issues. Oil is not coming back from evaporator. Oil is staying in the evaporator or migrating back. Checked eductor and it's good. I have to keep adding oil just to get it running. I take out what I added, after I get it running.

  2. #2
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    How fast are you losing oil and what is the load % of the machine?
    Complete log of machine would be useful in giving a educated answer.

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  3. #3
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    SanchezHVAC said:Today 02:20 PM

    Chiller running at 80% with Run Capacity Limited-high Compressor Lift
    Chilled water delta p: 7.7 psi
    Entering chilled wtr: 57.2F
    Leaving " ":51.5F
    Chilled water delta T: 5.7F
    Evap rfgt temp: 49.2F
    Evaporator pressure: 44.5 psi
    Evaporator approach: 2.3F
    Condenser Delta P: 5.2psi
    Entering cond water: 84.3F
    Leaving "": 91.7F
    Condenser rfgt temp: 92.9F
    Condenser pressure: 109.5 psi
    Condenser approach: 1.2F
    Oil pressure: 30.9
    Oil temp: 132.3F

  4. #4
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    How often is it losing oil? Does the oil ever come back to the sump? is the chiller starting and stopping a lot?

    Normally when I have a XR that has no oil in bottom sight glass and is down on low discharge superheat I try to run oil pump to see if it makes oil pressure. If it can't make oil pressure ill add a few gallons until it makes oil pressure. At that time ill start the chiller. If its a VFD machine ill supervise VFD target speed to 100% and ill limit the guide vane target to around 1%. Once the machine starts running I watch my discharge superheat (discharge temp - condenser refrigerant temp). Normally its 20-35 degrees. If the cooler is saturated with oil and you open the guide vanes oil will hit the impeller and your discharge superheat will take a nose dive. Thats why I limit the guide vanes. Start opening your guide vanes slowly in increments of 1-2% and keep an eye on your discharge superheat. As you open guide vanes your discharge superheat will drop. I try to keep my discharge superheat around 15 degrees. Let the machine run a little bit. As the chiller recovers oil your discharge superheat will widen. As the discharge superheat widens slowly open your vanes. You keep doing this until you get your oil back or your vanes are all the way open and your discharge superheat is above 20 degrees. Once the chiller has recovered all the oil and my oil level is above the top sight glass ill drain the oil level until its just above the bottom of the top sight glass. I do this in case it recovers more oil after I'm gone. I normally try to go back to the job at a later date to remove more oil if its above the top sight glass. Hope this helps

  5. #5
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    It's seems like it's losing oil in just a few day Now the 19XR next to the one I'm working on , is doing the same thing. Another did something with the surge settings and that's what is probably causing it.

  6. #6
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    Surge prevention settings has nothing to do with oil loss.

  7. #7
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    After you get the chiller running do you see oil return? Try to get your oil level up to middle of top sight glass. Make sure your chiller isn't doing a lot of stoping and starting. Also make sure you aren't running water through chiller. If the chiller isn't running make sure the pumps are off.

  8. #8
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    When I added two gallons of oil yes, I did see the lower sight glass completely full. The top sight glass was at the bottom. What can be causing this?

  9. #9
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    Quote Originally Posted by SanchezHVAC View Post
    SanchezHVAC said:Today 02:20 PM

    Chiller running at 80% with Run Capacity Limited-high Compressor Lift
    Chilled water delta p: 7.7 psi
    Entering chilled wtr: 57.2F
    Leaving " ":51.5F
    Chilled water delta T: 5.7F
    Evap rfgt temp: 49.2F
    Evaporator pressure: 44.5 psi
    Evaporator approach: 2.3F
    Condenser Delta P: 5.2psi
    Entering cond water: 84.3F
    Leaving "": 91.7F
    Condenser rfgt temp: 92.9F
    Condenser pressure: 109.5 psi
    Condenser approach: 1.2F
    Oil pressure: 30.9
    Oil temp: 132.3F
    Curious what is design information?

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  10. #10
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    First thought that the float was sticking, but we took it apart to check and it's good. The eductor is good also.

  11. #11
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    no way it could have been the float. If you had a float problem you would have seen your evaporating refrigerant temp take a nose dive until the chiller trips on low refrigerant trip. If you don't see this you don't have a float problem on a 19XR.

    If you have a design sheet that would be great but its not end of the world if you don't.

    I just looked at your log. Your evap approach isn't bad at 2.3 degrees. Should be closer to 1 degree.

    your delta T on evap is a little low If your chiller is running around 80% and your chiller is a 10 degree machine like most your delta T should be 8. Yours is 5.7 degrees. your chilled water delta P is 7.7 it should probably be closer to 5#s. I would close off my leaving chilled water valve until I got closer to 5#'s or a 8 degree delta T

    Your condenser water side looks good. This chiller should not be running in high lift as you have stated. If its running in high lift in these conditions and its not actually surging then you need to change your surge prevention settings. Do you have P1/P2 & T1/T2 or P1-P4 & T1-T4 or Tsmin and Tsmax?

    Surge prevention should not cause it to not recover oil!!!!

    Typically from what I see its normally starting and stopping a chiller too much in 24 hours. By doing this you never give the chiller time to recover oil. The other problem is when people run cold condenser water through chiller. I also never run water through chiller when the chiller isn't running.

    You said you have seen it recover oil. So that tells you your oil recovery system works!!!

  12. #12
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    T1: 1.5F
    P1: 50psi
    T2: 10F
    P2: 80psi
    That's all the info I have in hand at this very moment.

  13. #13
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    I know that the pumps are always running, these chillers are not on a BAS. Just start/stop command. I do know that one of the chillers there has always had problems with tripping on excessive surge.

  14. #14
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    Dont change T1 or T2 settings. Since you have this style of surge prevention I would raise both P1 and P2. I would start off by raising P1 to 55-57 and P2 to 90. After making these adjustments back out and see how its running. See if the high lift goes away. If it goes away monitor the chiller. I prefer to setup surge prevention so it just goes into high lift right before a surge. Most people make mistake by setting it up too conservatively. After making these changes if its still in high lift id raise P1 to 60 and P2 to 95. Then recheck to see if its in high lift. From this point id make smaller adjustments until high lift is gone.

    This is the worst surge prevention for this chiller. Mainly because you only have two points. So the surge line is a straight line. P1-P4 & T1/T4 is much better. You might see if you can get a carrier tech on site. We can download a newer version of software. At that time they should be able to setup your surge prevention settings.

  15. #15
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    Do the chillers run 24/7? who or what controls the pumps? The chillers can easily start and stop the pumps. All of our chillers have contacts in the starter to control pumps. I would suggest doing this. I prefer to never run water through a chiller if its not running. Most likely you have a ISM in starter. The contacts are located on the ISM. one set of contacts for each pump. Run low voltage through these contacts. 120V or less!!!!

  16. #16
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    Thanks for all the info, wished you could have seen my post sooner. More than likely I will be at the job site again. Hopefully I'm able to reach you when I'm there.

  17. #17
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    Im curious what your evap approach is with the chiller running at 100%. If its 2.3 degrees at 80% it could possibly be 3-4 degrees at 100%. Its possible this this chiller is low on refrigerant. If the chiller is low on refrigerant it can't recover the oil at lower loads. Also if its low on refrigerant it can make you see high lift alerts and surging. Due to wide evap approach

  18. #18
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    I will have that info today. Is there an easier way I can get ahold of you? Do you have Facebook messenger?

  19. #19
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    Email me

  20. #20
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    Just curious what is the fluid in the cooler / evaporator ?

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