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Thread: MP39 or 409a??

  1. #1
    Join Date
    Jul 2002
    Location
    Chandler, Arizona
    Posts
    231

    Question

    Hey Gents,
    I need a little help here, I like many other am primarily HVAC but I want to do more Bars and restaurant equipment.

    So, I am working on a walk in refrigerator Stores Mexican food, it is an R-12 system that has a leaking LL drier. Simple enough to fix except that I and everybody I know is out of R-12. So out goes the Idea of pumping down.

    Now I am trying to decide which refrigerant to use. This units condensing unit is below the Evap. I am planning on Removing the comp and try to drain as much MO as I can and replace with ABO or POE.


    I tried to do a lot of research from the DuPont website pdf files, and even the Tecumseh, all pretty much say the same thing about both refrigerants.

    The only real difference I found was that with MP39 you can refill if it get low over and over... Seemed like a plus to me. even though I am fixing the leak.

    But I still perplexed, IT all seems like a lot of Mfgr mumbo jumbo.. I Need some real advice,,,, SO I turn to you all and ask for help.

    What I really want to know is: What is the difference between 409a & MP39? And which would you all recommend?
    Appreciate any help, thanks.


    Jay.
    Semper Fi!




  2. #2
    Join Date
    Jan 2005
    Location
    Veterans Home Yaphank, NY
    Posts
    2,309

    MP39 vs 409A

    I, who was a strong advocate of 409A when it first came out would recommend MP39. too many problems with high head pressure with 409A and having to retrofit with MP39 at my own expense. So if you can take advice from ex Army refer specialist (me) stick with MP39
    RAM Teaching Tomorrows Technicians Today.

  3. #3
    Join Date
    Jul 2002
    Location
    Chandler, Arizona
    Posts
    231
    Thank You IceHouse!

    Head pressure was my main concern, being that I live in the valley of the sun. I am glad to hear you say it since That was way up on my list..
    I am more than likely going to use MP39, I still want to hear more expierences one way or the other.

    Thanks Jay.

    Semper Fi.

  4. #4
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,328

    R12 to MP39 Head Pressure.......

    One thing to remember when using a blend like MP39 is that higher discharge pressure is normal. If you compare R12 at let's say 130F condensing temperature (which would be typical for 100F+ ambient) the expected discharge pressure would be 180 psig. With MP39 under the same conditions the discharge pressure would be 220 psig. While shockingly high to many folks, this is perfectly acceptable, normal and per the P/T charts......and while the pressure is in fact higher, the amp draw is typically comparable to that of R12.

    I've used MP39 (R401A) since 1994 with no significant problems so I stick with it. Changing the original mineral oil to 50% minimum AB oil was initially required by DuPont but that was rescinded early on. Changing oil, while it's not generally necessary, it's still a good practice wherever it's practical (like with a semihemetic).....hermetic cans just aren't worth the trouble.

  5. #5
    Join Date
    Feb 2002
    Location
    Yuma, Arizona
    Posts
    925
    Have been using R-420 (RB-276) for the last three years. Had used MP-39 and R-409, both good, but again head pressure being a problem here in the warm areas.
    Have found that R-420 is a little lower head then the other two in equal temps. Have put it in ice cream/shake machines and POU's also walk in's. No problems to date. Have left the oil that's in the unit there, no changing.

    Yuma,
    What is snow? Is it that white stuff in a freezer?

  6. #6
    Join Date
    Jan 2005
    Location
    Veterans Home Yaphank, NY
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    2,309

    Red face Re : MP39 vs 409A

    Yuma you mention R420, please enlighten me as to who makes this as I have tried all the so called R12 replacements the best was R416, but nobody in my area stocks it anymore. All they have is MP39, 409Aor "Hot Shot", but these all have higher head pressures and some of these kitchens are hooter then hell.
    RAM Teaching Tomorrows Technicians Today.

  7. #7
    Join Date
    Jul 2002
    Location
    Chandler, Arizona
    Posts
    231

    Thumbs up

    Hey Guys,

    Well I did the job today,, I at first I wasnt going to change the oil in the Hermitic compressor because I thought that would have involved Removing it and dumping it over, which I did not feel like messing with.

    But while at ARS I saw a little pump made by NuCalgon, its pretty cool, it has two plastic tubes and pumps about 1oz when you push down on it. Its really easy to use, I just fished a 1/4 tube down thru the suction to the bottom and started pumping,

    http://www.nucalgon.com/nucalgon/nuc...D?OpenDocument

    I am really glad I did, I was pulling out Mineral oil that looked like pure coffee probably from running low on juice for too long. Then I pumped in some ABO, Removed and repeated it a couple of times till the oil looked better. ARS only had ABO by the gallon, so I had plenty to play with. I feel so much better since I decided to do this.

    afterwards I changed the drier and buttoned it back together, cleaned coil,, etc etc, put in the MP39, Fired it up, and boy did it sound good and Ran real nice, Its like breathing new life into an old unit.

    I was happy, Customer was happy and tomorrow after I go back to repair the evap drain and get paid, I will be really really happy .

    I also wanted to thank everybody for the advice it really helped me out alot, especially when it come to second guessing myself on dilemas like these.

    One more thing for Yuma, I am also curious about RB-276, I have read good things about it, and I think I even posted a question about it here in the past. but there was no real expierenced response about it. So please "enlighten" us some. thanks.


  8. #8
    Join Date
    Jun 2001
    Location
    San Diego, CA
    Posts
    1,149
    I currently have 6 MP39 retrofits, the oldest of which was retrofit more than 2yrs ago.

    From deli cases to walk-in coolers, condensing unit above or below, self contained or remote - all are still in service. In fact, one of the walkin coolers ran as an emergency freezer at 20* for a week once without icing up :O .

  9. #9
    Join Date
    May 2004
    Posts
    1,853
    I use Mp-66. Pressures are closer to R-12 than Mp-39. I have hade good success with it.

  10. #10
    Join Date
    Feb 2002
    Location
    Yuma, Arizona
    Posts
    925

    Re: Re : MP39 vs 409A

    Originally posted by icehouse
    Yuma you mention R420, please enlighten me as to who makes this as I have tried all the so called R12 replacements the best was R416, but nobody in my area stocks it anymore. All they have is MP39, 409Aor "Hot Shot", but these all have higher head pressures and some of these kitchens are hooter then hell.
    It is made by Refrigerant Management Services, and the head pressure at 150f is a smig lower than R-12. (234.3-R420 to 234.6-R12) And comparing them to MP-39 or R409, (148f MP-39 is 277.0, psig and R-409 is 279.5 psig)
    They also call the stuff Free Zone, and their webb site is http://www.rmsgas.com . I get the stuff through A.R.S. here locally.

    Yuma
    P.S. Have been using R-420 for over three years and have had no problems at all in our high temps of the summer.

    [Edited by Yuma on 02-10-2005 at 11:00 AM]
    What is snow? Is it that white stuff in a freezer?

  11. #11
    Join Date
    Feb 2005
    Location
    Barrie, Ontario
    Posts
    4,622

    MP39 or 409a??

    Up here there is a direct R12 replacement called RS24 from Nova Scotia. Not alot of guys use it yet but it's gaining a little momentum. Tried 409 muchly. MP39s okay I guess, but RS24, even though it's a blend, doesn't have as much glide and operates with "near normal" R12 pressures. I have been greatly successful at running this stuff with cycle defrost as well. I hope this stuff stick around for awhile.

  12. #12

    Thanks Yuma!

    For the info, I have to try that whats the percentage rate n the charge difference, if any versus r-12? I also tried 409a on some old small low temp applications, and they carried the oil well back to the compressor, what do you think about this , and 420 a? I seen hot shot break down on low temps and fail to help oil circulation, and or 416 a,snake oil refrigerant at its best,lol.

    [Edited by coldspot on 02-22-2005 at 12:40 AM]

  13. #13
    Join Date
    Feb 2002
    Location
    Yuma, Arizona
    Posts
    925
    coldspot, On units of more than a pound I have found 85-90% of charge is good. On the smaller units 90-95% of charge. The company says charge to 90% of name plate. I have used this in ice cram machines and freezers and again no problems noted. I also will only say I use this in a high ambient area and can not address issues where it gets below freezing (ambient) for any length of time. (Our lows around may get to a COLD 30f once a year)
    I hope that helps,

    Yuma
    What is snow? Is it that white stuff in a freezer?

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