One important consideration, surprisingly not mentioned in many of the R22/R407C retrofit guidelines, is elastomeric seals and O-rings exposed to R22 (or 400-series blends containing R22) will have swelled and will tend to shrink when the new HFC refrigerant is introduced.
This would include shraeder cores as well as regulators, solenoid valves, etc.
Some manufacturers made R22 units and charged with nitrogen. If I replace old one and install the nitrogen charged unit and charge in R22, do I cross the line or it is no problem? So far here in Ontario, almost nobody regulate the a/c and refrigeration, but I heard TSSA will take care of a/c and refrigeration too.
All my units here at work ( except new stuff in the last year + ) are R-22 - Air Conditioning application. That is 150 A/C s and a 134a 125 ton Carrier screw chiller.
I am just about sold on MO-99 as a ' retrofit ' solution; that being said, I have 2 new Liebert systems going in that are 407C, and a few replacement RTUs and shakers that are R-410a.
Haven't pulled the trigger on MO-99 yet, but according to Refrigerative Supply ( out largest wholesaler who has great customer service ) , it should be a relatively pain free process.
Anybody else out there using MO-99?? Perhaps something as good or better? Horror stories?
Have done two stores with mo-99.
Upsides, lower discharge temps
Downsides- Loss of capacity, oil return in questionable. We had a problem with a used pack we put it. Some of the mt cases were high in temp. When we cleaned the screens it was logged with oil. We through some POE in the system as some have rumored it helps.
The second retrofit when relatively painlessly. We don`t service that store so I can`t tell you if they had any oil problems.
I was amazed compared to 22 or even 507. I could grab the discharge line and it wouldn`t burn. This eliminates the need for liquid injection if you have an lt 22 system but on the flip side puts quite a blow to the heat reclaim if they`re using it.
Honeywell is supplying us with their brand for free as a test pilot for the store we`ve been having trouble with. We should get around to it mid summer. I`ll post the results when they`re in.
In air conditioning applications with the higher velocities I bet Mo-99 is a dream.