People sometimes overlook that if the equipment is in an area that needs heat anyway (many residential units), the efficiency issue becomes much less important since many of the "losses" aren't really losses.
In addition to the thermodynamic differences of replacement refrigerants, Some use different oils (POE oils?)in the refrigerant piping which is incompatible with the oils typically used in R-22 systems. The changeover would require a system flush-out before converting. Some of these oils will...
I think Elite makes something: http://www.elitesoft.com/
I also found an old diskette (DOS 3.1?) labelled pressure drop calcs, probably from a vendor. If you're interested, email me, and I'll shoot you the file, no guarantees!
I gave expert testimony for a case involving some equipment I was hireed to get working. I kind of fell into it, and had a good relationship with the attorney. I am interested in doing more forensics and expert testimony in the HVAC/Commercial buildings field. I think my credentials are...
You can look at the ASHRAE site www.ASHRAE.org If you're not familiar with them, they're the American Society of Heating, Refrigerating, and Air Conditioning Engineers. There are more & more worldwide chapters. If they don't have the info directly, check the chapter links for a local chapter...
If you want interference fit you can look at HI-Lok. I think the spelling is right. If you just want a standard fastener, It sounds like a Vandal-proof fastesner may work for you. They come in various head configurations other than normal screwdriver heads
