Wow! r22 at johnstone today wass 599 dollars. my god.
what is everyones opinion on the favorite replacement for low temp,med temp, and ac?
whats worked best so far? also are txv's being changed regular or have they generally worked ok as is with adjustment?
johnstone is pushing 422b, also mo99 looked ok? lets get the opinions flyin!
There's a few threads on this subject and 407a . Lots of good info.
Here in sweden the R22 is commonly replaced by 407C or 410A for air cond and chillers, 404A/507 for low and mid temp, sometimes even for low temp chillers (even 134a is used for mid temp on applys earlier used R22).
Imho I'd prefer 507 for low and mid temp, chillers also, makes the compressor runs much softer and a li'l bit "colder" discharge temp than a equal charged with 404A, besides that it has greater capacity for picking up energy and "leaving" it.
407C for airconds, but however, i really dont like it... for f*** sake... Put 507 there too
We have R507 here, but you don't see much of it except for some supermarket chains. R404A is much more common.
Originally Posted by Putte
Actually, I've been leaning toward using R404A for R22 medium temp conversions...similar to what you're doing with R507. It reminds me of 20-30 years ago when we had compressors dual rated for either R22 or R502 MT.
R407C for A/C work is pretty good, but MO99 (R438A) is fast becoming the flavor of choice because it's quick and easy, but there's no reason R507 (or R404A) won't work for A/C as well.
has anyone had luck with mo99 in walk ins, reach ins. going to a class about conversions tomorrow, so any opinions based on experiance would be great.
(R438a) is been used alot in the A/C conversions down here in the big supermarket chains and 407a for racks it was R422d but that faded quick..
Originally Posted by icemeister
Mastic its whats for dinner!
If the only tool you have is a hammer, you tend to see every problem as a nail. Abraham Maslow
For small refrigeration and comfort cooling, I don't see the need for conversions of existing equipment at this time. $20/lb is not much when you are only talking about a few pounds of refrigerant.
I recently decided not to purchase anymore R-22. I had a walk in cooler the other day that blew the charge. Repaired the leak, replaced the dryer and charged with MO99. No problems so far, I did notice a lower head pressure. Also, I had to open the TXV a little bit since it was running a little higher superheat. This was the first time using MO99. Hopefully no problems in the future.
Originally Posted by kklobas
Another thing too, If you have been in the field for a while. We had to do the same thing when R-12 was being phased out. I figured we did it then, might as well do it now.
"The best preparation for good work tomorrow is to do good work today"
thanks everyone. Andy that chart is pretty scary- 20-30% capacity loss? that's total capacity if i'm reading write. Seems most equipment would not work after conversion with that much capacity loss? m0-99,422b examples.
Anyone else have good luck in walk ins?
been using and will continue to use R-407F for MT/LT over the rest.
Thanks for writing this and posting it for us here Andy.
Originally Posted by Andy Schoen
For me, it stresses an important point which, I must admit, I have often overlooked when analyzing system performance...ie, volumetric efficiency, and the factors which can affect the volumetric efficiency of a compressor and so, its performance. As you explained about clearance volume and re-expansion, all compressors are not alike, and so the effect of something like pressure ratio will have a greater affect for some more than others...thus the need for calorimeter testing.
What really surprises me however, is the huge difference between the expected performance stated here and that which we have been told to expect from the refrigerant manufacturers.
For example, this article from DuPont includes a chart indicting expected performance of -6% for MO99 (R438A) vs R22 for low temp at -31.7ºF SST/40.6ºF SCT (-25ºF/105ºF) while your results for -10F/115F show a loss of nearly -20% (even at a slightly lower pressure ratio).
They state their numbers are based on calorimeter tests, but they don't say what type of compressor was used. Have they got a secret supercompressor for testing just to make their data look good, or what?
I suspect the answer lies in "or what".