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  1. #1
    Join Date
    Feb 2008
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    TWIN SCREW VS SINGLE SCREW-which is best?

    Twin screw or single screw. which screw compressors, in efficiency and reliable trouble-free long operation, are best in your experience. I am in the midst of two option and in the decision procedure. Carrier 30XB and Daikin EWADH (INVERTER SYSTEM). Price is not much difference in the both. COP is also not much differenced as per the provided documents. IMO, Daikin seems good. Its inverter and single screw is attractive compare to carrier. What you think

  2. #2
    Join Date
    Feb 2009
    Location
    UK
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    Hi single screw, less moving parts

  3. #3
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    Dec 2007
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    Idaho
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    Use to take care of a couple Daikin frame 4 dual screws at a fish hatchery, only turn off during maintenance and run between 60 and 80% 24-7-365 with no lag chiller. Had over 80,000 hours with only a slide valve failure on #1, keep telling them get a lag chiller it’s going to go down and you will lose a full campaign of sockeye salmon and the dang thing just keep running.

  4. #4
    Join Date
    Apr 2016
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    Maryland
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    If you are dealing with comfort cooling , I would ask for two machines with two compressors and independent refrigerant and water side circuits .If not possible , have two smaller machines with separate refrigerant circuits . A pass gasket failure on the cooler / evaporator divider gasket can be a real headache

  5. #5
    Join Date
    Feb 2008
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    Dubai
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    Thread Starter
    Quote Originally Posted by hvac6470 View Post
    Use to take care of a couple Daikin frame 4 dual screws at a fish hatchery, only turn off during maintenance and run between 60 and 80% 24-7-365 with no lag chiller. Had over 80,000 hours with only a slide valve failure on #1, keep telling them get a lag chiller it’s going to go down and you will lose a full campaign of sockeye salmon and the dang thing just keep running.
    really, i didn't understand what you intended. what is the content

  6. #6
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    Feb 2008
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    Thread Starter
    Quote Originally Posted by CHILLERSVCMAN View Post
    If you are dealing with comfort cooling , I would ask for two machines with two compressors and independent refrigerant and water side circuits .If not possible , have two smaller machines with separate refrigerant circuits . A pass gasket failure on the cooler / evaporator divider gasket can be a real headache
    i think you misread, i am planning two chiller, and the proposed unit from Daikin is asymmetric compressor with independent refrigerant circuit. my question was about the type of compressor model, twin screw and single screw. which is the best considering its long time reliable operation and efficiency.
    Attached Thumbnails Attached Thumbnails Slide1.jpg  

  7. #7
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    Quote Originally Posted by moideen View Post
    i think you misread, i am planning two chiller, and the proposed unit from Daikin is asymmetric compressor with independent refrigerant circuit. my question was about the type of compressor model, twin screw and single screw. which is the best considering its long time reliable operation and efficiency.
    After seeing the Single screw image, I can see why anyone would misunderstand your question! I also thought you were asking about single compressor vs dual compressors. Not the number of rotors in the compressor. I'm not familiar with Daikin, and I don't know if that model is available in the USA, but I do know that I had no idea such a compressor even exists.

    My stock answer to "What chiller should I buy?" is buy from the manufacturer who has the best service support in your area. If you are providing that service, I suggest buying what you're familiar with and what you trust.
    In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".

  8. #8
    Join Date
    Nov 2004
    Location
    up in the hizzy
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    3,389
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    I recall years ago there was a problem with the MQ single screw compressors having gate rotor failures that sent junk throughout the refrigeration loop. I really like the Bitzer "twin" screws.
    There is not better place for the working men than the union! 100% UA the only HVAC union!

  9. #9
    Join Date
    Nov 2011
    Location
    East Side
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    Personally, I think the twin screw has less chance of failures.

    The single screw relies on a seal mounted on the star gate that can wear over time.

    The twin relies on rotor clearance and a liquid oil seal.

    Are you installing water or air cooled? Water cooled machines are more susceptible to failure due to low oil pressure, caused by cold tower water.

    I think all the manufacturers have pretty much nailed down mechanical failures due to manufacturing or design issues. I believe a lot of chiller failures are actually caused by, incorrect application, poorly designed installation, or running them outside their design conditions.

  10. #10
    Join Date
    Apr 2016
    Location
    Maryland
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    Dunham-Busch made a good open drive screw machine at one time

  11. #11
    Join Date
    Sep 2013
    Posts
    6
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    Believe the Daikin comps are badged up Halls Screws ( J & E Halls ).
    See quite alot of then over here in the UK.
    The Daikin Inverter screws are really nice bits of kit.

    E

  12. #12
    Join Date
    Sep 2002
    Posts
    27,019
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    The D/B open-drive screw compressors could be damned reliable. I saw them with 100,000+ hours on them.

    What I could never figure out was why they couldn't correct the rotor profile to make them quiet. The guys in Hartford told me for years that it was impossible. But then the Japanese did it and suddenly there were almost-silent screw compressors. <g>

    PHM
    --------------


    Quote Originally Posted by CHILLERSVCMAN View Post
    Dunham-Busch made a good open drive screw machine at one time
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  13. #13
    Join Date
    Jul 2018
    Location
    Kazakhstan
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    In my service I have Carrier chillers with twin screw and McQuay with single. And I cant to say, what is better or worse. If you have sufficent tech support, info and qualification. Units are designed and installed properly, have smart service and maintenance, compressor s performance is in operating envelope, in most cases this chillers have reliable trouble-free long operation. In my opinion of course...

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