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R22 replacement
Hello Everyone,
As the price of R22 increases and it’s essentially well on it’s way out, I’m looking at retrofits.
I think I’ve asked before, but perhaps something new has hit since then.
Have you retrofitted any R22 walk ins or residential units and what did you use? what did you have to do.
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13 Replies
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You would open a can of worms. This changes daily.
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From what little research I’ve done on it, the answer is indeed “a can of worms” 🙂 However, I’ve also found that the manufacturer is often the only reliable answer. Some will point to 410A, others 421A. The biggest pain of course is in the fact that you can’t just top off. You need a full evac/recovery followed by a full top off.
I’m amazed you even have any R22 left. You clearly had the foresight to stock up! 🙂
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You’d be surprised, it’s still sold pretty much everywhere. just got really expensive recently.
My main concern is the POE and MO currently used in various R22 systems.
407C and A are good for POE where MO99 is good for MO
Most of my walk ins are mineral oil according to the manufacturer so MO99 would be a logical choice.
I did some calculations yesterday with an enthalpy chart for both R22 and MO99.
They are very similar, similar pressures, similar compression ratios and the latent heat is also very similar, within a BTU of eachother.
There’s a slight loss in net cooling but that’s about the only major difference I could find.
That and it’s a blend which in theory will fractionate if there’s a leak, which R22 does not.
410A is meant for residential A/C it’s not used in refrigeration, at least not that I’m aware.
Some systems if changing refrigerant require seal changes, sight glass changes and TXV changes, I’m hoping to avoid all that if possible.
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I’m not an expert, I just play one on tv 🙂
This is definitely a hot topic and one I look forward to learning more about.
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Haha, fair enough.
It’s a tricky subject for sure
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Having gone through the R12 and R502 changes of the 90’s, I can relate to this. Plan on doing 4 oil changes in the equipment while it is still running. From MO to AB. Copeland has a optical densometer to measure the specific gravity after each change so you can tell when your dilution rate is low enough to make the last change a POE. By POE in small cans, as it is very hydroscopic and once opened you have to discard any not used. R407A works the best for medium temp and low temp applications. But R427 isn’t as fussy with lubricants if you are changing a down system. Still, it’s good practice to replace the oil with a interim oil of AB. It you have systems that have suction pressure control to facilitate defrost each cycle, Your going to have a big learning curve dealing with the glide. Digital gauges are a must for this. And you may see some evaporator areas (lower) that just want to ice up. Being your in the south, you shouldn’t have the problems that my area creates. The outside compressors on suction control just don’t want to start when it’s 20 below. Your not going to find one for all. Especially if you have any cap tube systems.
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Because this is a ever changing topic, I highly recommend you find your local RSES chapter and go to one of there meetings. You can then ask some of the best in the industry on this.
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When it comes to oil changes;
If you have Copemetic compressors, oil flushes are a breeze. There is a tap on the side of the crankcase for oil. The trick is to make a 1/4 inch flare fitting up with a tube to reach the bottom of the correct length. You can then use the service valves and push the oil out and your vacuum pump to pull new oil in. You will need to also make a fitting with a tube long enough to reach the bottom of the new oil can. File the end at a angle so that it can not seal on the bottom. Oh, and you’ll also need a short charging hose. Like 12 to 15 inches long. Longer ones make to much resistance and take forever.
With hermetic compressors, it’s another ball game. You have to first determine if it has a loop on the return line inside the compressor. They just are not drainable. Others just fasten to the case and the compressor can be removed and tilted/inverted to drain.
Most compressors built after 1993 have been shipped with AB or POE oil. And they were required to be labeled as to what oil they had. One of the problems we ran into in the 90’s was that not all motor winding insulation was compatible with POE and would break down.
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Most of what I’ve got are either scrolls or recip hermetics, so it’s all hermetics for me, except for 1 which is a semi hermetic but it runs 404, so no big deal yet.
I’d rather avoid the oil flushing and all of that, lineset is well over 100′ so I’d rather not be messing with it.
MO99 can apparently do POE and Mineral Oil whereas 407C and A are POE only, so perhaps MO99 will be the better option for me.
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Fortunately, I changed the evaporator coil & condensing unit on the one R-22 walk-in-cooler I had after I started working at this school district 10 years ago. All my other refrigeration is R-404A or R-134A, except for the newest school built last year. That cooler and freezer are running R-448A, with which I have absolutely no experience.
On a side note, to keep my existing R-22 running at home after I had to repair a refrigerant leak a few years ago, I converted it over to MO99. It’s been running great since (knock on wood).
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That’s cool, good to know.
I’m dumb in that regard, I’ve replaced evap coils on 2 different walk ins and didn’t convert -.- should have, but was too worried about getting it up and running.
That’s really good to know, we got a bunch of resi units we want to change over as well as commercial walk ins.
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We do a bunch of Pizza shops in Phoenix and we’ve retrofitted almost every still working walk-in with R407C. I know it should be R407a but it works very well and it’s low head pressure keeps the units from hitting HP cut out during summer. We have had 0 problems retrofitting with it and the cost is excellent. Also it works just as good for old R22 Package units. Just make sure your super heat is good!
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Okay, good to know.
Thank you.
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