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  1. #40
    Join Date
    Sep 2003
    Location
    North-Central Ohio
    Posts
    22
    Please - no offense lennyb, but you need to supply a lot more info for a good diagnosis of the problem.
    SOUNDS, like it's low on charge, but what else could be wrong? Icing on the TXV (output) on low temp isn't necessarily a problem, but have you accurately checked SH & SC?, is there a sight glass?, did this system function normally before this call? - many others have raised good questions as well which is why I stated that more info would be a HUGE help.

  2. #41
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,168
    Any freezer at -10 no matter which refrigerant is gonna have a vapor line temp at the TXV bulb of 10 or less. Other wise the freezer wouldn't be able to be at -10.
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  3. #42
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,716
    lennyb,

    From reading your last couple of posts, I think that you are having some difficulty understanding superheat.

    On the low temp stuff that I work on, a suction line of -10 to -15 at the evaporator isn't abnormal at all.

  4. #43
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by Lennyb View Post
    So your saying that the Evap line temp at the TXV bulb should be 6-10 for a 404a freezer? Also maybe im just slow but I was under the impression I understood SH
    No. First I think you have an idea how to find SH. SH is the difference between saturated suction temp and actual suction line temp. The SH should be 6-10 degree for this application.

  5. #44
    Join Date
    Feb 2012
    Posts
    21
    Evap is Baily M# BF200B-1
    TXV is a SBF5E-A-Z
    Compressor is a Copland
    EAVA1-021E-TAC-800
    208V 3HP. 60HZ

  6. #45
    Join Date
    Feb 2012
    Posts
    21
    I opened up TXV and SH is jumping around at 10 to 30, noticed right side fan is only running about 1/2 speed.

    Plan is to change Fan motor then watch and adjust SH, if its still jumping around I will change TXV

  7. #46
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    Quote Originally Posted by Lennyb View Post
    Evap is Baily M# BF200B-1
    TXV is a SBF5E-A-Z
    Compressor is a Copland
    EAVA1-021E-TAC-800
    208V 3HP. 60HZ
    I think you mean
    TXV is a SBFSE-A-Z
    Compressor is a Copeland
    EAVA-021E-TAC

    The Evap model number, I cannot find.

    But with this information, I would return the TEV to its middle position.

    I think you're under-charged or restricted. based off your 175# pressure

  8. #47
    Join Date
    Feb 2012
    Posts
    21
    Changed both fan motors and returned TXV back to center, de-iced both side of evap coil. Box got down to 16 Deg. and SH was still 50 Deg.
    My question is that I'm going by simple math equations. when my gauge temp says a neg temp it gets added to the suction line temp not subtracted correct?

  9. #48
    Join Date
    Feb 2012
    Posts
    21
    Another question.
    When working with refridgerants that im not used to working with how do I determine what is or would be a good running Temp/PSIG for the application.
    Such as
    409a Freezer
    414b Freezer
    414b cooler
    404a Freezer
    404a cooler

  10. #49
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,168
    Don't think about the pressure so much. Its always the saturation temp that counts.

    Weather 404a, 409a, or 414b, a -10 freezer means you'll have a saturation temp of minus 20 or lower when the freezer is at or near -10.

    Get some P/T charts.
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  11. #50
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,716
    Quote Originally Posted by beenthere View Post
    Don't think about the pressure so much. Its always the saturation temp that counts.

    Weather 404a, 409a, or 414b, a -10 freezer means you'll have a saturation temp of minus 20 or lower when the freezer is at or near -10.

    Get some P/T charts.


    Pressure is immaterial, it is the temperature that matters.

  12. #51
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    Quote Originally Posted by Lennyb View Post
    .
    when my gauge temp says a neg temp it gets added to the suction line temp not subtracted correct?
    You find the difference between the 2 numbers.

    a -25* SST and a +25* pipe temp = 50* superheat
    Last edited by Phase Loss; 08-18-2012 at 10:20 AM. Reason: I'm shot

  13. #52
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    Quote Originally Posted by Lennyb View Post
    Changed both fan motors and returned TXV back to center, de-iced both side of evap coil. Box got down to 16 Deg. and SH was still 50 Deg.
    For you to have a 16* box and 50* superheat, best case scenario that means your suction pressure is around 8 PSI -33* SST?

    I still think you have a restriction.

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