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Thread: 134-a vs. 404-a

  1. #1
    Join Date
    Feb 2004
    Posts
    126
    What is the advantage of using 134-a in a freezer? I know lower head pressure than 404a but suction is so low almost in a vaccuum. I just wanna know the reasons manufacturer's choose that over 404.

  2. #2
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,578
    4hg, 100 psig is a good pressure for a compressor to run. The discharge temps are lower on 134 and the gas costs less.

  3. #3
    Originally posted by Freezeking2000
    4hg, 100 psig is a good pressure for a compressor to run. .

    What?

  4. #4
    Originally posted by jerrycoolsaz
    Originally posted by Freezeking2000
    4hg, 100 psig is a good pressure for a compressor to run. .

    What?
    Have to agree. This is one reason R-12 went bye bye for low temp. Always want a positive pressure in suction relative to ambient. Might also want to check btu/lbs of refrigerant moved at low temp conditions.

  5. #5
    also even though head pressure is higher for 404a the compression ratio is greater for the 134a in a low temp application.

  6. #6
    Join Date
    Jan 2004
    Posts
    59
    134b sucks.................aaaahhhhhhhhhh

  7. #7
    Join Date
    Oct 2002
    Posts
    970
    Hate sucking in air on a low side leak.
    I work with the Chiller Whisperer...

  8. #8
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    Originally posted by gdavis
    What is the advantage of using 134-a in a freezer? I know lower head pressure than 404a but suction is so low almost in a vaccuum. I just wanna know the reasons manufacturer's choose that over 404.
    There is no advantage at all. It's a terrible idea. Why would you want to run in a vacuum to try and maintain a barely-low-temp box temperature?

    Go with 404A.

  9. #9
    Join Date
    Feb 2004
    Posts
    126
    I think this box was a Hobart but I am not sure. It had the cooler on the top portion and the freezer as the bottom. To me it is only a residential unit with commercial condensing units and a commercial body. Refrigerator here at home has more room than it does.

  10. #10
    Join Date
    Feb 2004
    Location
    Maine
    Posts
    483
    R134a is really only used in low temp for domestic fridges and freezers. They typically run 0 to 10 degrees F with a slight positive pressure. In a restaurant scenario you typically want -10 to -20. With R134a your gonna be in a slight vacuum at these temps. Any leaks on the low and you will be sucking in moisture laden air. Also running a compressor in a vacuum makes it harder to cool with suction gas. As others have said before there is no advantage to this. Only reason a manufacturer would use 134a is to cut costs.

  11. #11
    Join Date
    Feb 2004
    Posts
    126
    This box they keep at -10F because they put ice cream in there. They did tell me they have always had problems with the freezer portion of it but never a minutes problem with the cooler portion of it. Life goes on though

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