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  1. #1
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    Jul 2011
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    R-408A question(Evap temp) for low temp box

    For other Refer guys. Low Temp. Using R-408A, on a low temp box, what is the typical operation suction line temp/pressure?? at the evaporator? 24psi(-10) or 33psi(5 degrees)???

  2. #2
    Join Date
    Jan 2010
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    6,060
    Would depend on the equipment manufacturer.

  3. #3
    Join Date
    Jul 2000
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    Guayaquil EC
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    Quote Originally Posted by jeremyjp View Post
    For other Refer guys. Low Temp. Using R-408A, on a low temp box, what is the typical operation suction line temp/pressure?? at the evaporator? 24psi(-10) or 33psi(5 degrees)???
    Typically a walk-in freezer evaporator is selected for a 10F TD, where the TD is the Box temperature minus the evaporator temperature.

    So for a 0F box you should expect a -10F evap temp. For R408A that would correspond to a pressure of 21 psig at the evaporator.

    Smaller, self-contained freezers tend to have slightly higher TDs like 15F or so. Then your expected evaporator pressure would be correspondingly lower.

  4. #4
    Join Date
    Jul 2009
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    Northern area between Alantic and Pacific
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    Quote Originally Posted by icemeister View Post
    Typically a walk-in freezer evaporator is selected for a 10F TD, where the TD is the Box temperature minus the evaporator temperature.

    So for a 0F box you should expect a -10F evap temp. For R408A that would correspond to a pressure of 21 psig at the evaporator.

    Smaller, self-contained freezers tend to have slightly higher TDs like 15F or so. Then your expected evaporator pressure would be correspondingly lower.
    Good info,so what TD for walk in cooler and self contained cooler? Thanks.

  5. #5
    Join Date
    Oct 2011
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    Chicagoland Area
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    Quote Originally Posted by markvilleman View Post
    Good info,so what TD for walk in cooler and self contained cooler? Thanks.
    Don't know if I've ever heard of 408a in a med temp application. Again, it depends on the mfg. Grab a manufacturerers catalog. You can design systems with different TD's.
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  6. #6
    Join Date
    Sep 2011
    Location
    Plainfield IL
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    101
    Quote Originally Posted by markvilleman View Post
    Good info,so what TD for walk in cooler and self contained cooler? Thanks.
    Walk in coolers and self contained coolers are usually sized at 10 degree TD.
    Air conditioners sized at 20 degree TD.

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