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  1. #14
    Join Date
    Dec 2004
    Location
    Florida
    Posts
    121
    Post Likes
    I doubt its a oil reclaim problem and most likely not a charge problem either. This is a common problem when chiller is starting and stopping a lot. I noticed your condenser approach is a little wide. Your running around 4.2 degrees and it should be around 1-2 degrees


    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. If you don't need to add oil 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

  2. #15
    Join Date
    Dec 2004
    Location
    Florida
    Posts
    121
    Post Likes
    I just noticed your approach is around 2 degrees at 80%. Im curious what your approach is at 100%. Its possible dirty eval tubes or low on refrigerant. If its low on refrigerant then you could have oil loss problem at low loads.

  3. #16
    Join Date
    Jan 2015
    Location
    Somewhere making cold water
    Posts
    176
    Post Likes
    After adding oil, you are pulling same amount of oil back out? Curious if evap is becoming oil logged.

    Sent from my SM-G950U using Tapatalk

  4. #17
    Join Date
    Dec 2004
    Location
    Florida
    Posts
    121
    Post Likes
    I normally try to pull about the same amount of oil out that I put in. But it could have been a little undercharged with oil to begin with. I like to leave oil level around middle of top sight glass. After recovering oil back the way I stated earlier it should take about 2-4 hours to get all the oil back. This is the best way to get the oil back when chiller is going down on low discharge superheat. If the chiller is running in low discharge superheat you can't just start the chiller with 80% load and walk away. It will trip off on low discharge superheat if you don't limit the guide vanes. I will say that it does help if you have a load on the chiller. You can get the oil back quicker.

    I can look up to see if theres a bulletin on this but I promise the way I described in previous post is the best way!!!

  5. #18
    Join Date
    Mar 2018
    Posts
    2
    Post Likes
    Tcy612 would you be able to send me that SB

  6. #19
    Join Date
    Dec 2004
    Location
    Florida
    Posts
    121
    Post Likes
    Ive never seen this bulletin. I searched hvacpartners last week and couldnt find it. I dont need it to use. Im just curious if it actually exist. I went into pretty good detail a few post earlier about how to recover oil in a 19XR chiller.

    If somebody has this bulletin please post the bulletin# so I can pull it up on hvacpartners.

  7. #20
    Join Date
    Mar 2018
    Posts
    2
    Post Likes
    Thanks Carriermechanic Im going to a new account tomorrow Im not too familiar with Carriers I usually work on Yorks. I was told the chiller is shutting down on low discharge superheat so I was looking for some info. I did read what you posted and will try to use that info tomorrow

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