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  1. #1
    Join Date
    Jan 2014
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    7

    Smile First question of many.

    In a mini-split heat pump system(in my case, Fujitsu) I believe that there is oil going through the along with the R410A.
    What I would like to know is where does this oil come from?
    How does the compressor deal with any oil in liquid form?
    Thank you in advance for any information.
    Terry

  2. #2
    Join Date
    Aug 2013
    Location
    Visalia California 93291
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    655
    Oil travels with the refrigerant and comes from the compressor and is returned to the compressor.....Proper piping practices will ensure safe and proper return of oil to a compressor

  3. #3
    Join Date
    Jan 2014
    Location
    Mesa, Arizona
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    353
    Oil is already mixed with 410A. Look in the installers manual for instruction on acceptable line set lengths. I know with trane mini splits, if your line set has a rise of 20ft, you must add an oil trap to prevent slugging the compressor.


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  4. #4
    Join Date
    Aug 2002
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    Southold.calm
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    5,616
    Quote Originally Posted by Rubio480 View Post
    Oil is already mixed with 410A.


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    What?

  5. #5
    Join Date
    Jan 2014
    Posts
    7
    In a scroll or rotary compressor I can see the need for some kind of lubrication necessary to allow smooth movement of the scroll or rotary part to the compressor wall.
    As far as R410A having oil in it, all I have read states the kind of oils that will work with R410A, not in it from the beginning.

  6. #6
    Join Date
    Jan 2014
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    Mesa, Arizona
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    Quote Originally Posted by pecmsg View Post
    What?
    Let me rephrase, oil is already mixed with the factory charge of the condenser


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  7. #7
    Join Date
    Aug 2009
    Location
    Maine
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    3,237
    In the compressor itself.
    Quote Originally Posted by Rubio480 View Post
    Let me rephrase, oil is already mixed with the factory charge of the condenser


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  8. #8
    Join Date
    Jan 2014
    Posts
    7
    Thank you "Rubio480". That seems to make sense.
    If the oil is drawn in to the compressor from the suction,gas line, how does the compressor deal with the liquid oil.
    I do realize that accumulator will gather any liquid to the bottom and only allow the gas into the compressor;if this is the case wouldn't the oil eventually all be gone?
    I'm sure glad this forum is for dummies like me.
    Terry

  9. #9
    Join Date
    Jan 2014
    Location
    Mesa, Arizona
    Posts
    353
    Oil is liquid form at all times, it does not change state. It lubricates the scroll/rotor compressor. The oil travels back to the compressor, but is kept warm by a crankcase heater/trickle in some cases. Most cases, all the oil won't make it back to the compressor between cycles.


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  10. #10
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,783
    The oil originates in the compressor sump. Refrigerant is there, too. The refrigerant does not have any lubricant to start with.
    When the compressor runs some of the oil circulates with the refrigerant. Proper piping will ensure that the oil continues to return to the compressor instead of collecting in low places in the system. If the oil does not return to the compressor, the compressor will not have the lubricant it needs and will fail.
    Wasn't that easy?

  11. #11
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
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    5,060
    Quote Originally Posted by terry1 View Post
    Thank you "Rubio480". That seems to make sense.
    If the oil is drawn in to the compressor from the suction,gas line, how does the compressor deal with the liquid oil.
    I do realize that accumulator will gather any liquid to the bottom and only allow the gas into the compressor;if this is the case wouldn't the oil eventually all be gone?
    I'm sure glad this forum is for dummies like me.
    Terry
    There is an oil metering device in the U tube of the accumulator that will siphon oil back with the suction gas

  12. #12
    Join Date
    Jan 2014
    Posts
    7
    Not to beat a dead horse but I "think" I have learned about the oiling in a mini-split system.
    To me it appears that any oil that is going around the system is there because it got out from the compressor.
    The accumulator(in the suction line) will trap the oil as well as any liquid 410 and meter it ,sump, or what ever, to the oil reservoir(crank case, as it seems to be called some times).
    I hope this is correct because it is the only thing that seems to make sense to me.

  13. #13
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    18,386
    When the oil and refrigerant return to the compressor, they enter the compressor case, and most of the oil drops into the crankcase, leaving the refrigerant to be compressed, to pick up some oil on the way out, and go out around the loop again. If an appreciable amount of oil gets into some compressor designs (into the area where the refrigerant is compressed, such as a cylinder) damage can be the result. Scroll compressors are more forgiving, but even scroll designs allow the oil to drop out once inside the case.

    Does than help?
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