A Strategy for Refrigerant Conversion From R-22 to R438A
If you are in the maintenance or HVAC business you have probably heard by now about the R-22 phase out under the Montreal Protocol. Perhaps you even read my previous article on the subject (Retrofitting Reasons to use Dupont™ ISCEON® MO99™ instead of R410A). If you haven’t read it yet I recommend you read it before, or after, as it will give you a better understanding of the factors.
R-22 is being phased out by 2020 due to its ozone damaging ways. There was a short time that production of condensers that use R-22 had stopped. Now companies are manufacturing condensers that can use R-22 again. They used to sell them as pre-charged units with R-22. Now manufacturers have found that they can only sell them as dry units. Dry units need to be charged with refrigerant at the time of install.
Isceon M099 is a relatively new refrigerant brought on the scene by Dupont. There are some very nice qualities to this refrigerant a.k.a. R438A. It has very similar operating characteristics to R-22 without the ozone abuse. At the time of this writing you can get a twenty five pound can of Isceon for just a few dollars over two hundred dollars and a thirty pound can of R-22 for about one eighty ( expect these prices to change quite quickly, R-22 will most likely climb in price as its dooms day approaches. Isceon will most likely stay the same, or it may go down, or up, a bit as it gains popularity). Isceon has a pressure temperature relationship very close to R-22 so the majority of HVAC techs will have an easy time switching over. Oil does not need to be changed, system does not need to be flushed, (unless a compressor burned out), wiring generally does not need to be changed (always check manufacturer specs), evaporator coils do not need to be replaced. The one thing that does need to happen is the seals need to be replaced because the seals that were used with R-22 will shrink when charged with R438A (Isceon M099). This leads right into my plan of attack.
When you need to replace a condenser, this is the time to change over to Isceon. The new dry unit will have all new seals. If a system needs to be opened up for any reason, evaporator coil replacement, filter dryer replacement, etc…. or if a system has lost its charge due to a leak, these are all good times to retrofit to Isceon. Recover R-22 and use it to maintain your other R-22 units (after acid testing it and verifying it is ok to use). Make sure all Schrader valves, or other seals are replaced, a new filter drier is installed (anytime the system is opened), the system is leak tested with nitrogen, and vacuumed down to 250 microns (29.91 Hg) for a good amount of time to boil off any moisture. Now the system is ready to be charged with Isceon. The nice thing about Isceon is it has a cooler discharge temperature at the heart of the A/C (easier on the compressor).
Make sure to very clearly label the new units. Make it clear that they are charged with Isceon.R438A comes in a blue can so it would be good practice to color code the new units with a blue label that matches the refrigerant. Refrigerants should never be mixed or topped off with a different type. If you have several buildings in a complex and the condensers are nearing the end of their lifespan it may be smart to retrofit one building or so, year by year as a capital improvement. You can reuse good fan motors, blades, baffles, lids and such from the phased out units to better offset the costs and help make it easier to keep your remaining units working. This way you can phase into Isceon (R438A) before R-22 is phased out.
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