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  1. #1
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    Wink what is the best blend for low temp



    I tryd frig 12 & 414b I have found some problems with frig 12 on the older systems and on systems not size right it will not pull down to temp has it will with r12 I know the size needs to right but its a hard sell all the custermer knows is it work just fine befor w/ frig 12 there is a diff. of coill temps from 414b .
    r-414b has lower coil temp . what do you like to use 414b,mp66,frig12 what works for you and why the one I like is mp66 it looks close to r12 in low temp



  2. #2
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    I like and exclusively use R-414b in my domestic refrigerators and freezers.

    There are four reasons:

    1) it does not require an oil change
    2) it does not require any system modification
    3) it is rated at 92btu/lb/hr heat transfer rate (terminology?)
    4) R134a is much too hard on the cap tubes and compressors as well as it doesn't seem to want to get cold enough.

    I have no problems with 414b unless it becomes fractionated - then it does strange things like make evaporators gurgle.

    If you want to make your system colder, then adjust your mixture by substituting 5-10% R22 for an equal amount of the 414b (i.e. if your system takes 8 ounces, then put 6 ozs 414b and 1 oz R22 and top off with the 414b if needed). But try not to overdo it because your head pressure should drastically increase and your compressor could stop working.

    My suggestion would be to braze the high and low side tubing together (about 4-6 inches or so long) or install a heat exchanger to help control the higher head pressure.

    Home made ones cost about $5 to make, commercially available ones cost about $20 but have a higher efficiency rating. I use 3/4 inch copper tubing for exchanger body, 3/8 inch coper tubing for the low side pass through and 1/4 inch for the high side pass through. You can make them smaller by using 1/2 inch copper tubing (actually it's 5/8" OD) for the exchanger body.

    Another item of interest is are you charging the system in the proper manner? Never go by the pound/ounce method but instead go by the low side pressure and ALWAYS charge as a liquid! ! ! The 414b will vaporize in the charging hoses, but that's OK so long as it doesn't vaporize in the DOT 39 bottle.

    Applaince @ room temperature (72F)...from a deep vacuum, SLOWLY put in the 414b until you get to 10 psig - if you see frost on the precess stub then stop charging immediately until the frost has disappeared. Start the appliance (pressure will drop to a vacuum), then continue SLOWLY charging at 5 psi, and stopping at 8 psi as soon as you see a pressure increase. Wait for the freezer to drop to about 35F or less, and your gauge pressure should drop about from 8psig to about 3 psig.

    Note that some systems will frost at the 5psi mark and usually operate at 2psi or less (those compressors that look like a ball or pumpkin in shape and typically have a drain tray attached to the top of it).

    I have managed to get some domestic refrigerator freezer compartments to as low as -10F at the middle settings on the controls by using the 414b & without running for a kazillion hours.

    I'm not sure what mp66 is....Do you have a cfc/hcfc/hfc number I can equate to?

  3. #3
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    suva mp66 from du pont = r-401b

  4. #4
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    Did I forget to mention that R414b mirrors R12?

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    WE have used R-414b alot in small systems. The other tend to show there refrigeration glide. So keep with R-414b its also close to R-12 so far. M-39 is ok but its got superheat problems and can cause premature compressor problem. I have had test compressor and we have changed them to r-414b also adding heat exchanger will help keep the head down.
    Preston Roy Powell
    www.thinkcool.net

  6. #6
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    I like R-409A for low temp. R-416A (frig 12?) for medium temp.

  7. #7
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    409 recomends an oil change below 15 degrees. That is above domestic freezer temps. It is just AB oil though. I drill a small hole near the bottom of the compressor. I use a piece of copper tube to prevent the bit from going too deep. Drain at least 1/2 the oil and recharge with AB. Fairly fast and painless. 50/50 - AB/mineral oil is compatable.

  8. #8
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    Zolar

    Would you mind posting a picture of your home made heat exchanger. Im intrested . Thanks

    Abe
    Any opinions, statements and facts expressed in this message do not constitute legal advice in any shape or form and is given for a general outlook in nature. You are advised to seek appropriate and specific professional assistance from a regulated and authorised advisor for definitive advice.

  9. #9
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    As soon as I get time, I'll post a pic of my home made heat exchanger.

    Since summer is here, I have been rather busy. Please forgive the delay.

    Zolar

    PS about drilling the hole in the compressor....how are you sealing the hole? Braze it? What about oil degradation and contamination from incinerated oil left over in the compressor?

  10. #10
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    I know of some refrigeration 'ing-in-eers' that put 134a in compressors that use mineral oil without changing the oil.
    Any comments?

  11. #11
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    Originally posted by superheat
    409 recomends an oil change below 15 degrees.
    hmmmm. . . my information syas miscible with all, and denotes no such requirement for lower temps. Who advertises that recommendation?

  12. #12
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    We toyed with it in auto a/c units and in an outdoor condensing unit placed below the evaporator. As far as I followed it, the condensing unit below the evaporator worked fine. The auto a/c application worked for about 6 months. But the van had 120,000 miles on it, so it is not certain whether the mineral oil or other factors contributed. We also just added poly oil on top of the mineral charge with varying degrees of success. Not very scientific, but the evidence is that published recommendations are quite conservative. We have avoided experimenting with customers' equipment, of course.

  13. #13
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    I have quit using 409a because of poor performance at high ambient, especially with low temps. Not lubrication problems, but high head. I'm surprised to hear it preferred for low temps in Texas!

    Perhaps one reason is that hot weather is so rare here (San Francisco Bay Area) that many units are undersized (low bid!) and many stores not air conditioned.

    I have switched to 414b until I hear of something better.

    Rog

  14. #14
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    About drilling a hole in a compressor to drain the oil out....

    How do you seal the hole back up? Braze a screw into the hole? Or a nail? Did you have to use oxy-acetylene torch to reseal it?

    How would using R134a in a mineral oil or AB oil domestic refrigerator fair? IE would the compressor overheat or what?

    Just a note: I recently replaced a soda vending machine compressor (Locked Rotor of 31) with a refrigerator compressor (Locked Rotor 25) and added one of my home made heat exchangers to it. The head pressure was about 175 psig and suction pressure was 20 psig, using straight R414b.
    Amp draw on the compressor was 4 amps @ 120VAC 60Hz

    By the way, domestic refrigerators here in the US RARELY if ever are rated in Horsepower. Nearly all are rated in Locked Rotor.
    Is there a conversion chart somewhere?

  15. #15
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    Actually, locked rotor amps are not ratings at all.

    You MUST refer to the model number and look up the capacity, rating conditions and refrigerant from the mfg's tables, available from any wholesaler and most mfg's websites.

    Some model numbers incorporate BTUs and some, horsepower, but without the rating conditions, even those are incomplete.

    As far as heat-exchangers are concerned, if you will chart the performance of a system on a pressure-enthalpy diagram, you will discover that the apparent gain from lowering the liquid temperature is completely offset by the rise in temperature of the suction gas.

    It may be easier to visualize if you use the box method. Draw a diagram of your system and then draw a box around any component, group of components, or the entire system. Once your system has reached equilibrium (stable operating conditions), energy (electric or heat) crossing the boundary into a box must equal energy leaving the same box. A liquid-to-suction heat exchanger removes some heat energy from the liquid line and sends it back to the compressor without going through the evaporator. There is no net gain in efficiency. The compressor sees the same energy no matter which route it takes. It can even cost efficiency if you locate the HX close to the compressor and heat that would normally have been lost to the environment in a long liquid line ends up as superheat to the compressor instead.

    The purpose of the liquid-to-suction heat exchanger is to reduce the potential for flash gas in the liquid line, especially in systems with long vertical rises, reduce the potential for floodback to the compressor and to improve evaporator performance per unit of mass circulated by reducing flash gas in the evaporator.

    Rog

  16. #16
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    Just a dumb question here please...........

    if you were to take one of your work vehicles contents (ie tools, equipment, supplies) and pack it all into a geo metro, would you have space for all those manuals you refer to? LOL

    I need to be able to instantly look at a compressor and instantly know without a doubt if it will work on a refrigerator or whatever. The locked Rotor is the only way to determine this information without having to memorize umteen zillion sets of information.

    You see, I take compressors off of one piece of equipment and put them on another piece of equipment. I don't actually need to know what oil is needed since I use R414b.

    The bigger the locked rotor rating, the more btu's the compressor can transfer (assume all things being equal) or better yet, the more ***** it can pump & at higher pressures if necessary.

  17. #17
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    I tried an experiment on my own refrigerator. I measured amp draw of my compressor before adding a 10 ton heat exchanger, and again after adding one.

    When I go from 3 amps down to 2, what does that tell you? It tells me that by adding the heat exchanger I am saving electricity.
    The theory is this: if the compressor has to do less work, you save money. If the suction side pressure is higher because of a heat exchanger, the compressor doesn't have to compress a 5 psi gas to a 175 psi liquid - it gets a 10 psi gas to work with.

    Less work = less heat = less wear and tear = more money saved

    Just changing the size and shape of the box........

  18. #18
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    Blend for R12 replacement in low temp.

    I am the inventor of several refrigerant blends
    to replace R12.

    R-406A (called Autofrost in the automotive
    market) has been around since Aug 1990.

    You will see the same temp/pressure
    characteristics as R-414B (ICOR Hotshot),
    however the mineral oil return will be
    much better in low temp use. R-406A is
    miscible in mineral oil down to around -40
    or -50F. It is classified by ASHRAE as A1/A2.
    It can become "weakly" flammable if most of
    it is fractionated (vapor leaked) off. The 10%
    remaining liquid can be put in a jar and
    lit with a propane torch, and it only has
    flames 1-2 inches high and it self extinguishes
    after 1 or 2 seconds from breakdown products.

    In normal HVAC technician work, such as
    unbrazing a line with a small amount of
    R406A remaining, one will not even be able
    to detect the weak flammability tail, since
    it will be masked by the residual oil burning
    at the joint. Looks the same as unbrazing
    a joint with R12.

    If you absolutely have to have an ASHRAE
    A1/A1 refrigerant, we also make R-414A, the
    sister to R-406A. It is more or less R-406A
    with a little R-124 added to suppress the
    tiny flammability tail to stop all the
    political bitching. R-414A is miscible in
    mineral oil down to about -10F. You can use
    AB (alkylbenzene, e.g. Zerol) if you need
    lower. R-414A passed the tough UL2182
    flammability test, worst fractionation
    at 100C, which caused R-500, HP80, MP39
    (R-401A), etc. to "become" flammable due
    to the elevated ignition temp. UL and ASHRAE
    hemmed and hawwed a couple of years, and
    lowered the wff temp from 100C down to 60C
    or such, and everybody else except for R-414A
    had to retest, so the big boys could get
    their UL back again. Pretty stupid bs, since
    the ASHRAE and UL tests do not take into
    account the oil in the system. When you count
    the oil.. R406A and R414A are pretty much the
    same. Even R12 burns with oil in it.

    In 1993-1994, we setup ICOR in business to
    package bulk R-406A for us in 25lb cylinders.
    In 1995 we caught them making extra R-406A
    "on the side" outside of the license agreement
    (I am the patent holder.. US 5,151,207) and I
    had to sue them in federal court to get them
    to stop. We also had started on GHG-X4
    (which became R-414A) due to all the fuss
    the auto industry was making and trying to
    "ban" R-406A on the almost nonexistant
    flammability. ICOR "stole" their first
    "HOTSHOT" which was almost exactly the same
    as GHG-X4, from us. Competent legal
    counsel determined
    that their first "Hotshot" would have infringed
    in my patent covering R-406A, and the in
    the settlement, ICOR agreed to reformulate
    Hotshot (which became R-414B) to have no
    more than 1.5% isobutane and no more than
    9.5% R142b, both of which are very crucial
    to be able to return mineral oil to the compressor.

    R-414A and R-406A have 4%
    isobutane and 16.5% or more R-142b, hence
    their much lower operating temps in mineral
    oil. Both work in AB oil as well, but not
    required.

    Since R-414B is formulated "just outside" my
    patent, it is marginal in carrying mineral oil.
    It may work in some systems and not in others.
    I measured R-414B mineral oil miscibility at
    +18F in 150 SUS mineral oil.. which is still
    better than FX-56 (R-409A) at +32F in mineral
    oil. Dupont is open and upfront on R-401A/B/C
    and they state to use AB oil only.

    So, R-414B, R-409A will work at low temps
    (and so will R-401A (MP39)) if you change
    the oil to AB (alkylbenzene).

    Formulations by weight %

    R-409A R-22/142b/124 (60/25/15)
    R-401A R-22/152a/124 (53/13/34)
    R-416A R-134a/124/600 (59/39.5/1.5)
    R-406A R-22/142b/600a (55/41/4)
    R-414A R-22/142b/124/600a (51/16.5/28.5/4)
    R-414B R-22/142b/124/600a (50/9.5/39/1.5)

    R600 is N-butane, R600a is isobutane
    R22=weak mineral oil miscibility
    R124=almost no mineral oil miscibility
    R152a=zero mineral oil miscibility
    R134a=zero mineral oil miscibility
    R600 = very good mineral oil miscibility
    R600a = very good mineral oil misciblity
    R142b=moderate mineral oil misc, gets much
    better when R600a is also present.

    Also, FR12 (R416A) has way too low pressure
    temp curves (about 12F "warmer" than R12),
    so it will make a Fridge out of a freezer
    if system or pressures not changed. R416A
    with only 1.5% N-butane has almost non existant
    miscibility in mineral oil as well.

    R-414A has been "FSP" (factory) approved
    by Whirlpool corp for maint on R12 equipment.
    Whirpool Corp is now the exlusive nationwide
    distributor of R-414A. I believe this is the first
    R12 replacment blend which has achieved a
    major OEM blessing and standing behind it.

    For more info on R-406A or R-414A..

    http://www.autofrost.com or call 800-622-5008 in
    the US.

    --ghg, inventor, R-406A, R-414A, Cooltop, etc.
    ghg@autofrost.com

  19. #19
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    George, happy to see you drop by this forum.

    Igniting any barbeque grills this summer???

    Sporlan's refrigerants chart which the Prof maintains has the following information on your refrigerants:

    R-406A: Tc = 241.7°F, Pc = 708 psia, Vc = ? Mol Weight = 89.86
    R-406B: Tc = ?, Pc = ?, Vc = ? Mol Weight = 88.58
    R-414A: Tc = 231.3°F, Pc = 682 psia, Vc = ? Mol Weight = 96.93
    R-414B: Tc = 226.4°F, Pc = 666, Vc = ? Mol Weight = 101.59

    Any additions or corrections will be duly recorded.
    Prof Sporlan

  20. #20
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    Thank you George. The data you provided helps me in my decision making process. What is the boiling point of your R406a?

    I want something I can put in ANY domestic refrigerator without having to worry about high head pressures and what kind of oil I need to use.

    With the R414b, I didn't have to worry about anything except putting it in too fast or in soda pop coolers where I need to consider excessive head pressure with respect to a small compressor capacity.

    Can I put your R406A into a frig that takes R134A as a replacement? Or use it in a car A/C system?

  21. #21
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    Here's some of my desires:
    (domestic and small appliances use typically)

    1) I want to have a nearly 'universal' refrigerant I can use without regard to head pressures or type of oil.

    2) A refrigerant in answer to my 2nd most common complaint (My ice cream won't freeze) - ie I need a refrigerant that has a boiling point and decent btu rating such as 'boils at - 40F or -50F'

    3) A refrigerant that won't make me have to put my kidney for sale on ebay to afford to buy it.

    So far, HotShot is the closest to 'universal' I can find.

  22. #22
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    PS it's a real pleasure to meet one of the creators of a needed product.

    Pleased to meet you George!

  23. #23
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    To Prof Sporlan and Zolar1

    I have not lit any more grills since
    1996 or so.. after Dave Barry Column
    spread it all over the world.. Local fire
    dept really got pissed 2 years after the
    fact and threatened to turn me in to the
    BATF. Doing this now, would surely get
    one labeled a terrorist.

    There never was a R-406B, there was a
    "GHG-HP" refrigerant, only made 3 cylinders
    of it.. it was R22/142b/600a (65/31/4).
    It was made on a bet from Walt Pasko in
    Ft Lauderdale FL, that "There aint no such
    thing as an A/C too cold in south FL"..
    and this was my response. GHG-HP ran
    higher heads (only intended for MVAC -
    automotive A/C), with active high pressure
    cutoff switches, and condensers were built to
    take 450 PSIG. GHG-HP delivered 23-25F duct
    air on "max" on 100F ambient humid days.
    Evap ran at 19F, and frosted all the way
    back to the compressor. GM low side accum
    got as big as a football (iceball) after
    a long trip. Cont run compressors such
    as the V5 needed a "defrost timer" to
    off the comp for 15 sec every 3-4 mins to
    keep ice off the evap. It sure felt good.
    Made it onto the EPA SNAP approved list,
    but never into mass production. Cust said
    that R406A worked well enough. Limiting
    factor was the GM style evaporator which
    would blow out at 175 PSIG.. Heat soak
    from the engine causes a refrigerant pressure
    spike, 30 mins after the engine is shut off
    on hot days as the liquid heat pipes from
    the condenser back to the evap. GHG-HP
    maxxed out at about 150-160 PSIG during
    this spike from the heat soak.

    Jim Calm's ARTI refrigerant Database listed
    GHG-HP as a "candidate for R406B", which
    is where you may have seen it, but we never
    submitted it.

    ----

    to Zolar1.. ICOR runs around telling you
    that HOTSHOT (R-414B) is a "DROP-IN" for
    everything, all oils, even PAG..

    We try to be a little bit more truthful
    then ICOR.

    1) Others have told us that in many apps
    that R-406A is about as close to a DROP-IN
    for R12 that they have ever seen.. But this
    must be qualified to being small "DX"
    (non flooded evaporator) systems. Those with
    Exp valves may need some adjustment on
    some systems (Prof Sporlan I am sure knows
    more about this than I).

    2) R-406A has a "glide" of around 12-15F
    at most temps.. simlar to R-409A, 414A, 414B
    are all similar performance and glide. R-406A
    is miscible in mineral oil at much lower temps.
    -40F for R406A, -10F for R414A, +18F for R414B,
    and +32F for R409A.


    3) Oils.

    ICOR says PAG oil is fine with R-414B.
    We say to see www.autofrost.com/oil and
    see PAG oil turn black in 3 days with
    R414B (or R406A, R414A or any CFC or HCFCs)
    unless it is the rare "daphne" or double
    end capped PAG oil which can tolerate CFC/HCFCs.

    It has been known since 1990-91 that almost
    all PAGS are totally destroyed by even minute
    amounts of chlorinated components, with R11
    being the worst.

    POE/ester oils.

    While R406A, R12 and other HCFCs and HCFC
    blends will not quickly destroy POE oils
    made for HFCs, we still say to use only AB
    or mineral oil in R406A/R414A.

    CPI Engineering, a mfgr of POE/ester oils
    has told us that it is possible to make POE
    oils which work fine in R12, and HCFC blends,
    they ARE NOT THE SAME POE/Ester oils which are
    made for R134a and other HFCs.. POE/Ester
    oils made for R134a and HFCs will become overly
    miscible in R12, R406A (and R414B) and HCFCs
    and "thin out" too much, kind of like using
    kerosene in your engine crankase..

    People who have inadvertantly used R406A
    in hermetic compressors with POE oil, have
    seen them run fine for 2-3 months, then
    bust bearings, rods, and other lube related
    failures, due to overly thin oil. I am sure
    this happens with R12, R414B, R409A, and
    other HCFC blends run in POE oils as well.

    Lifetime tests with R406A/R414A in mineral
    oil have slightly exceeded those of R12
    in compressors.. (provided discharge temps
    are kept below 300F to keep the R22 component
    from breaking down).

    Note: if you are using pure AB oil, it may be
    wise to add 3% mineral oil, since pure AB
    may not "foam". Some older compressors rely
    on oil foaming to cover all the bases.

    hope this helps
    --ghg

  24. #24
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    Yes George, you are very informative!
    Now, all I need to do is 2 things - find out where I can buy the 406A and for what price? I already had to sell my unborn son's kidney to buy my last batch of refrigerant...LOL

    I usually buy from Johnstone Supply locally, but United or one of the others might be a little cheaper.

    Just about all the systems I service are cap tube types. Typically domestic refrigerators, with some soda coolers and reach in coolers.

    From what I gather from your above information, I can reasonably assume that i can substitute R406A for any R12 cap tube system and can make the units much colder?

  25. #25
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    R406A more info for zolar1

    Boiling point. Since R406A is a zeotropic
    blend, it boils over a range, called a "glide",
    around 15F range. Dew point is about -12F and
    the Bubble point is around -26F (R12 BP is -21F).
    R406A, R414A/B are pretty much the same in
    the bubble/dew points and glide. Mineral oil
    miscibility is what is different.

    This "glide" causes condensation to take place
    a "range", rather than at a single temp. This
    expands the "phase change" region in the
    condenser, the area where most of the heat is
    rejected.. The desuperheating (hot gas cooling
    down) and subcooling (liquid cooling down)
    regions become smaller.. The phase change region
    rejects far more heat than the other two regions.
    Since R406A (and the other similar zeotropic
    blends) can reject more heat, the cool better
    as well.. Often 6-8F colder in car A/C with
    orifices.. maybe 2-3F colder in exp valve
    car A/C. Pulldown times in fridges and
    commercial equipment has been reported to be
    much faster with R406A than with R12.. probably
    from the same reason.

    Bobbie Burke (ATC) in Bloomington, IN, not
    far from you, is our main midwest distributor.
    Call him at 800-622-5008 to see who may stock
    R406A in Cincy. He can also ship to you.

    United and some Johnstones used to stock
    R406A, however, ICOR's Lies were able to
    get them to drop R406A and switch to HOTSHOT
    (R414B). It as amazing how dishonesty pays
    off in these times.. look at ENRON. You can
    go to your United Branch and see if they
    still have any R406A left.

    Last year, when United switched to Hotshot
    from R406A, the locals who had been using
    R406A for years were so pissed off, that
    they switched ALL of their heating and cooling
    business purchases from the Lafayette, IN
    United Store over to Leming Supply who
    carries R406A. The local United Store almost
    went out of business since they lost FAR more
    than the R406A sales.. (lost furnace, A/C,
    parts, and other HVAC business).. Leming's
    business is booming from this move.
    --ghg

  26. #26
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    At $195.00 per bottle for the R406A is a bit steep. I thought buying direct would be a lot cheaper, especially with a company who's trying to rectify a bad sitaution and regain consumer confidence (for something you apparently couldn't help)

    I figure about $125 to $140 range would be more appropriate of the price since the middleman would be cut out.

    My mistake I suppose.

    When I can afford it, I'll try the 406a, but it might be a while since I'm a single person business now.

    Thank you

  27. #27
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    I read about your "Cryo-seal"

    Which version would be needed for the 406a and the 414b?

    I couldn't find a price anywhere (as usual).

    Thanks again

  28. #28
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    Well George,
    No one here in Cincinnati that I could find carries the 406a. Much to my wife's displeasure, I ordered one of your 25lb bottles of 406a.

    I asked about being a distributor here, but there is a 1 pallet minimum (yeah, like I have over $8,000 laying around).
    I was hoping to maybe be able to drop ship from your warehouse at the distributor prices (cust pays me full price, I drop ship from you to them)

    I am a skeptic sometimes. Sorry

  29. #29
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    Zolar1, check your email
    --ghg

  30. #30
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    Originally posted by zolar1


    I need to be able to instantly look at a compressor and instantly know without a doubt if it will work on a refrigerator or whatever. The locked Rotor is the only way to determine this information without having to memorize umteen zillion sets of information.

    You see, I take compressors off of one piece of equipment and put them on another piece of equipment. I don't actually need to know what oil is needed since I use R414b.

    The bigger the locked rotor rating, the more btu's the compressor can transfer (assume all things being equal) or better yet, the more ***** it can pump & at higher pressures if necessary.
    It's hard to know how to answer this, because I don't think you want to hear it. You have found a way of doing things that seems to work and when your misapplied compressors fail, you can blame it on the age of the used compressor or some such. In the interest of others who may pass this way, however, I'd like to set the record straight.

    Using the locked rotor rating is probably about as accurate as using the weight. You mention Johnstone as a supplier. Check their catalog. They have lists of compressors for every mfg they sell (as do all wholesalers). You will see that they are rated by temperature range, horsepower, BTU's at given evap temps and by refrigerant. If you are saying you have no room for even a Johnstone catalog, I don't buy it.

    In a previous post, you mentioned that you took a refrigerator compressor and placed it on a soda box. Probably a low temp now working as a midtemp. Not a good practice. Profitable, perhaps, but not good engineering.

    Originally posted by zolar1
    I tried an experiment on my own refrigerator. I measured amp draw of my compressor before adding a 10 ton heat exchanger, and again after adding one.

    When I go from 3 amps down to 2, what does that tell you? It tells me that by adding the heat exchanger I am saving electricity.
    The theory is this: if the compressor has to do less work, you save money. If the suction side pressure is higher because of a heat exchanger, the compressor doesn't have to compress a 5 psi gas to a 175 psi liquid - it gets a 10 psi gas to work with.

    Less work = less heat = less wear and tear = more money saved

    Just changing the size and shape of the box........
    It tells me that other factors were at work that you did not measure. It requires more work, not less, to compress a higher-pressure (more dense) gas. Remember, superheat is heat added to the suction gas above the temperature corresponding to the saturated pressure. So we're not talking of differences in pressure anyway, but in enthalpy (heat content).

    If anything, though, I'll bet the system with the HX was starved and operating at low suction and condensing. This could give you a 33% drop in power consumption, but at lower suction, the compressor would be less efficient and you may have sacrificed 50% of your cooling effect.

    Remember, a refrigeration system is an equilibrium system. Changing one factor affects everything in some way. The system will shift to a new set of operating conditions. You need to monitor and evaluate all the conditions before you can truly say you have achieved what you claim.

    Hope this proves useful to somebody.

    Rog

  31. #31
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    Thank you Rog for the insight.

    About the catalog - Yes, I carry a catalog, but I look at the nameplatye on a given compressor and it doesn't tell me a darned thing except volts (SOMETIMES), and Locked Rotor. The rest of the numbers are gobblygook and meaningless to me. You see, I have no 'Rosetta Stone' with which to compare numbers to what the catalog shows. I can match up pictures, but that's about all. The LRA# is what the person who taught me went by, so that's all I know at the moment - hence my reason for being here....to learn more and more. Perhaps he was wrong...I dunno since I have no common frame of reference in which to equate his methods to what most call the 'norm'.

    continued.........

  32. #32
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    Regarding the HX I installed - the evap makes a quiet 'whooshing' sound from time to time, and with the controls set midway, the freezer hovers around 0 deg F, the bottom around 35.

    Just for the record - I'm not into perpetual motion machines. I look at things a little differently and try to apply other principles that DO work in areas that seem to defy reason. Sometimes it pays off, sometimes it doesn't.

    I believe Albert Einstein made the statement, "Genius is 1% inspiration, 99% perspiration", but I could be wrong.

    As long as an Idea works and and costs less, does that diminish the value of the idea?

  33. #33
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    Rog is correct, one has to be careful
    on "non standard" uses to make sure parameters
    are not exceeded. Using a low temp compressor
    in med or hi temp use can result in overloading
    it and shortened life. Low temp compressors
    have more displacement per HP than med or hi
    compressors, since they operate at lower suction
    pressures.

    Sometimes you see a compressor that can
    be used under multiple service conditions, but
    the refrigerant is changed to make up for
    the displacement per HP factor.

    Sometimes a given compressor will be rated
    for low temp using R502 (higher pressure
    refrigerant), and for Med and Hi temp
    service using R12.

    One should always monitor the compressor
    discharge temp as part of service or
    experimenting, especially when "pushing
    the envelope", like trying to make a household
    fridge do -30F for extra hard icecream ,etc.

    A thermocouple or bead type thermometer should
    be used to check compressor discharge temp,
    right at the CAN. It no case should it
    exceed 240-250F.. since at those temps, the
    temp in the discharge valves is at 300F.

    Above 300F R22 (in most of the R12 replacement
    blends) will break down and make carbon and
    acids.. And a few degrees hotter, the oil
    will start to char..

    --ghg

  34. #34
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    In horizontal ice cream cases such as those manufactured by Hussman, the Copeland (low temp R-12) semi-hermietic compressor is not even rated for R-502. Hussman (and other manufacturers) will utilize these for very low temp R-502 at -30F to -40F evaporator in a cap tube system.

    But do you know what? Don't use 408-A as a replacement. It doesn't work!!!!! I'm not sure what it is about it.

    Any ideas?

  35. #35
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    Did you charge the R-408A as a liquid?

    All R-4XX refrigerants need to be liquid
    charged or their composition will change.

    R-408A is composed of: (weight %)

    R-125/143a/22 (7/46/47)

    Neither R-125, nor R-143a are miscible in mineral
    or AB oil at all, that leaves R22 which is
    very poor in mineral oil at -30F.

    AB oil would be a MUST I would think or mix
    in some POE oil.. or a squirt (upto 10%)
    of R-290 (propane) would make the AB oil
    return ok. "Zerol" is AB oil.

    What didnt work about it?
    --ghg

  36. #36
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    I believe Albert Einstein made the statement, "Genius is 1% inspiration, 99% perspiration", but I could be wrong.
    The statement is accurate, but Thomas Edison is credited with it.

    He also said: "If we all did the things we are capable of doing, we would literally astound ourselves."
    Prof Sporlan

  37. #37
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    You're right Prof ...Right Quote, wrong person...LOL

  38. #38
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    Regarding life span of the compressors I use - I can get used compressors regularly andf keeps a small stock of them on hand. If one goes out and the item is still under my 90-day warranty, then I'll replace it.
    My customers don't care about quality. They just want it fixed CHEAP. Hence, I use used compressors and HotShot (for the time being anyway), which is what manufactureres call 'designed obsolence' or 'designed service life'

    As long as it lasts just beyond my 90 warranty, my conscience is clear (unless they want to pay be fair market value for goods and service rendered).

    I want to learn more about this trade. It seems my past mentor's training isn't "gospel" and I am weak in many areas. But this will change. Starting with this place, and the R406a I'm buying.

  39. #39
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    Aiyub,

    I think I may be able to mail you a sample of my homemade HX's.
    I made 2 of them, one larger than the other. (Now if I can just remember where I put them...lol)

    I origionally made them to reduce flask gas in the cap tubes, but discovered that they can make the freezer part of a domestic frig colder if the HX size isn't too big. (I have a way to sort of boost the performance a little.)

    You see, I was modifying domestic refrigerators to accept a normal compressor instead of the junk rotary compressors (which usually failed) that came on some of them. It takes me about 3 hours to redo one of them from start to finish. I noticed that the freezers barely got to +5 or+10 before adding the HX. Once added, the freezers got to -10F without any problems.
    Many of them are still in use today, long after the 90 day warranty expired.

    Zolar

  40. #40
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    Also, I got out my Johnstone Supply catalog. NOWHERE in that catalog is there a conversion chart for ANY of the numbers on a compressor nameplate.

    Sure, you can look up a compressor by application, but nothing tells me who makes a given compressor, what it's application is, nor what kind of oil it uses.

    So, when some scrapper hands me a compressor, I can only go by the LRA number and volts if it's listed.

    The 134a compressors are usually labeled though, so I can assume the type of oil in them.

  41. #41
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    Zolar1
    I recall an article in the Ashrae magazine a couple of years ago that had a case stated for using mineral oil in R134.It was to do with diary case type cabinet refrigeration.
    Must see if i can dig it out. Theoretically anyway it was reasonably interesting argument put forward.Never saw any feedback..Maybe the guy is still paying for it.but...

    How do you guys get on when recharging systems when they develop a leak in a part of the system where fractionlised takes place. Do you recover all and charge with new refrigerant.

  42. #42
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    Wellllllllllllll,

    In domestic frig's, fractionalization doesn't seem to be too big of a problem, unless it's very severe.

    ICOR recommends that you recover and recharge with new refrigerant if fractionalization occurs. But really now, how can you tell on somebody's frig if it happens??

    From what I understand, the R22 component of HotShot is what is lost first. I know a few that simply pull down the system, fix the leak, put it back in, add more refrigerant, and 'ship-it' without any problems.

    About mineral oil and 134a....

    I went to a site listed from one of the super-fixers (Prof Sporlan maybe???) and saw a cap tube bleed off from the high side to the low. Perhaps 134a could be used in such a system with mineral oil provided an oil seperator and oil return line could be utilized, especially on a long vertical run. Then oil return would not be a problem?

  43. #43
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    Anyone hear of a product called "Cool Up'?

    It's sold in Canada and US techs can buy it with a credit card.

    Anyone know what it really is???

    Purportedly, you only use 1/2 as much charge as R12 listing, and get MUCH colder than R12.

    Cost is about $1.00 (US) per oz, sold in 6oz cans or 25lb bottles.

  44. #44
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    This thread caught my attention with the idea that suction gas / liquid line heat exchangers do not add efficiency. But do they increase performance? If I think about it, they should not increase performance either.

    But I found a little performance gain in my current R134a based water/methanol chiller when I added a heat exchanger (simply wrapping the captube around the suction line). It could be due to a reduction of flash gas in the captube, I don't know. It's there, and I am just doing my first steps in the realm of refrigerations.

    But now I want to change to a TEV since I experience huge load variations on the evaporator. A TEV is supposed to cope with that better than a captube.
    I planned to add a little HX too, with the main purpose of increasing superheat at the TEV bulb, and reducing the risk of flashing before the TEV. I would make the HX by just brazing together the suction line and liquid line for about a feet or so, and eventually wrapping it with copper wire to increase heat exchange.

    Is this still a good idea? I am not really concerned with the COP of the chiller. Performance is more important.

    Zolar1:

    In one of my first test setups, an R12 compressor filled with mineral oil failed when charged with R134a. The oil was quite acid, so it might have failed due to moisture.

    About your teacher: 10 engineers have 10 different methods of solving a problem. You teacher found that comparing LRA# is a valid method of selecting compressors.

    I do not agree. Motors with very different HP ratings can have the same LRA# rating. It is just dependant on the thickness of the wire used, the amount of wire used, and the quality of the connections. Not on HP rating.

  45. #45
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    I read an article in the Ashrae magazine talking about the practicalities of this or not as the case may be.

    It was a couple of years ago but the article was interesting.
    Some of his headings were;

    Improved working viscosity
    Reduced refreigerant charge
    Faster refrigeration on start up
    Reduced slugging
    and on
    All in all including a few potential problems (and that can start a thread on it's own proberly)
    it made interesting reading. I've not tried it, anyone out there?? who has and lives to tell the tale

  46. #46
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    when charging these small compressors and only the LRA is available, divide it by 6 and this will generally give you a reasonable FLA rating. The other thing is We carry two manuals that cover 90% of all the compressors in our area, Copeland and Tecemseh. The heat exchanger discussed is manufacturered by Sporlan called an "ALLS Valve", although Sporlan bought purchased the patent, they addmited it's efficiency is questionable at best. The heat exchanger sounds like pie in the sky engineering, It appears to be working like an unloader, pump the heat out and put it back in the low side, its an unloader, the run times will be longer is all. There's your missing amp.
    My wife says I don't listen to her....or something like that....

  47. #47
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    In my area, I know of an appliance dealer (used) that just dumps R401a into a frige and sends it on it's merry way to an unsuspecting customer. While his choice in refrigerant seems OK (colder frige I assume), one cannot help but wonder if the consumer has the right to know that their refrigerator WILL BE breaking down because of poor workmanship.

    Which is colder for a frige: R401a, R401b, or R409a?

    I am still struggling with customers crying incessantly that their frige won't freeze ice cream and that their 'old' frige always did.
    If I put any more refrigerant in (or run the psi low) then I risk compressor failure.

    Also, people still want their 5000btu A/C to blow out sub freezing air. They scoff at paying $150 to $200 for a decent A/C and want me to perform a miracle by 'fixing' their 5000 btu A/C to cool 5 rooms. Without switching to some expensive refrigerant like the R500+ series, is there anything better than R22 for a window A/C?

  48. #48
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    R134a in mineral oil.

    If you have a downhill run from the evaporator
    back to the compressor, it may work.

    uphill or horizontal, the mineral oil does not
    flow evenly along the walls of the tubing, but
    builds up until the line plugs up, and then
    flies back like a "snot" glob or a bullet.

    The high side liquid line sight glass will also
    look like "milk" instead of clear, since you are
    seeing a fine "dispersion" of oil droplets in
    the refrigerant, but not dissolved, like shaking
    up vinegar and oil salad dressing.

    --ghg

  49. #49
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    I remember reading an article in a 1999 ASHRAE magazine that gave arguments for using mineral oil with HFC's. It was well written and included some reasonable points.

    Has anyone actually done this in the field.

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    The heat exchanger discussed is manufacturered by Sporlan called an "ALLS Valve", although Sporlan bought purchased the patent, they addmited it's efficiency is questionable at best.
    Ahem….. the ALLS heat exchanger is manufactured by ALCO, originally under a license agreement with its inventor.
    Prof Sporlan

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