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  1. #1
    Join Date
    Jan 2009
    Posts
    86

    Carrier Difgital Scrolls, APD025 C/U, Chaging and New AHU Install

    WE just put a new C/U in and an NEw AHU at a Location.
    The Unit has Twin Digital scrolls. I have never installed something with the Digital scrolls, and I set the unit up for CType 3, which controls discharge air, but the compressors sound really bad when loading/Unloading. Also, the unit seemed to take quite a bit more refrigerant than I was expecting or than the Install Book and charging procedures Described. I never could quite gewt the unit spot on on the charging chart....My LL temp always seemed to be high for my given pressure.

    Are these Scrolls really noisy, almost sounding like a Reverese rotation when they unload, and they seem to cycle very erratically. Sometime unloading as short as 1 second and it has me worried....so I took away the the capacity control in the setup last night until I could research it making it run more like a traditional compressor. With it running loaded it sounds and acts completely normal.

    Am I just a bit over worried here?

  2. #2
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    Yes
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  3. #3
    Join Date
    Jan 2009
    Posts
    86
    It sounds really bad. I am thinking I have it grossly overcharged.

  4. #4
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    Wouldn't know , don't know what the unit is doing exactly.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  5. #5
    Join Date
    Jan 2009
    Posts
    86
    What would help in diagnosing, I can tell aything. I just can't get the ll temp down low enough to match the chart.

  6. #6
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    When you say hot I assume you had a thermometer on the system and were measuring actual temperature? What kind of pressure and temps did you record?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  7. #7
    Join Date
    Apr 2006
    Location
    mechanical room
    Posts
    1,255
    come on man

  8. #8
    Join Date
    Apr 2004
    Location
    San Antonio, TX
    Posts
    311
    Seen some digital scrolls in some AAON package units. They were Copeland's. They do sound weird when they unload, but the amp draw does go down, and the drastic reduction in hard starts ought to add considerable life to the boogers. I wouldn't mind having one them on my own house unit.
    G T T

    “In the end we will remember not the words of our enemies, but the silence of our friends”

    Martin Luther King, Jr.

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