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  1. #1
    Join Date
    Feb 2008
    Location
    Dubai
    Posts
    131

    super heat and sub cooling not required mension in commissioning report!?

    Dears, we have installed 20 numbers air cooled scroll chillers (SKM-LOCAL BRAND) and the manufacture submitted the chiller commissioned report. The report has missed some readings of superheat, sub cooling and discharge line temperature. I requested them from client side to include these readings for our future reference. Please look the replay from manufacture


    1. Suction super heat. (It varies depending on operating conditions and load. At full load and at design condition, it should be from 8-12F)
    2. Condenser sub cooling. (It varies depending on operating conditions and load. At full load and at design condition, it should be from 8-12F)
    3. Discharge line temperature. No fix value. It varies depending on operating conditions and load.

    Do you think it is not necessary in commissioning report? Which readings are fixed in refrigeration system!? As we know the Suction / discharge pressure/amps even chilled water in/out temperature are varying as per the condition! Do you think the manufacture stand is absurdity or lack of knowledge? Go to this link to know more about chiller.
    ACMR-410A

    http://skm.ae/chillers

  2. #2
    Join Date
    Apr 2007
    Location
    uk
    Posts
    203
    Moideen

    Sounds like a saleman's bull**** all of the above information should have been logged and provided to you as part of the commissioning report.

  3. #3
    Join Date
    Jan 2007
    Location
    Stongsville Oh
    Posts
    943
    Suction press and suction temp along with subcooling are the two most important indicators of refrigeration operation once the system is up and running. We are required to provide that info on startups even with systems that have processors that provide that on a screen. We verify the inputs. As Gibbo said " I call BS".
    ckartson
    I didn't write the book I just read it!

  4. #4
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,524
    What the manufacturer has provided is true. Superheat and subcooling and discharge line temperatures (and discharge superheat for that matter) do vary due to load and operating conditions.

    The reason for having a commissioning performed is to make sure that the system components can achieve these values. If they can not achieve these values (or ranges) then a component has failed or some other part is not operating at proper capacity. All a commissioning report does is to prove everything worked when new. Just have the contractor/manufacturer come back and either redo the log sheet or provide the information.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  5. #5
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    2,132
    Moideen, some OEM logsheets have the readings needed to determine superheat and subcooling, they just don't do the calculations for you. Is that the case here? With the possible exception of discharge line temperature, I would expect all the pressures and temperatures to be recorded that are needed to calculate it. If they are not, I think that manufacturer has a loose definition of "commissioning".

  6. #6
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    1,846
    Whoever is doing the commissioning is either simply being lazy or really doesn't know what they are doing.

    I'm sure it's much too late for this now, but one way to get those "minor" things taken care of is to hold back 10% of the money for the job. This is very common in construction. Typically it is called a Punch List. Final payment is not made until the punch list is complete. The commissioning could easily be part of the punch list.

    Once the installing contractor is paid in full, you have no leverage.

  7. #7
    Join Date
    Feb 2008
    Location
    Dubai
    Posts
    131
    thanks to all.I think they don’t know and there are not asked these type of requirements in their experience. These peoples are bringing the compressor from danfoss, heat exchanger from Italy, expansion valve from danfoss or sporlan, control board from china, condenser from local made. Assembling and selling the unit. Price is low compare to the branded items. Today the service engineer of manufacture is justifying his theory and repeating the bull....

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