R410-A
What a total F***ing joke!
For one, it's a multi-part gas, which means it will "stratify" while being compressed, reducing efficiency. Think of R134A for your car..... The hotter it gets outside, the WORSE it works. Get up in the mid 90's and it's hardly cooling at all!
For two, it requires higher pressures to operate. This means larger compressors, thicker tubing, and heavier coils. R22 runs at a maximum head pressure of around 300PSI while R410-A runs at 400+ PSI. This translates into higher energy consumption in the compressor as well as less efficient heat transfer due to thicker walls of the coils themselves, which in turn drives up energy consumption.
The kicker......it's Eco-friendly, right? Wrong! Even the EPA says so! Take one of their EPA certification tests! (I had to for my job, which is where this info comes from......directly from the EPA!) If you know your chemistry, R22 is a CFC which depletes the ozone layer (or so they say......the jury is still out since the hole seems to be closing inexplicably in the last decade...). R410-A is not. HOWEVER!!! R22 has a given "Greenhouse" rating, I don't recall the number off the top of my head at the moment. R410-A has a rating anywhere from 2-5x that of R22 depending on what study did the test!
So R410-A may not deplete the ozone layer, but it's not going to cool your house, it will create extra strain on the already straining utility grid, and it will cook us to death in the process. Good stuff huh?
For those of you interested in replacing your central or window unit, 2009 is the year to do it. 2010 signals the end of production for R22 appliances with the cessation of the production of R22 gas in the next few years. It's just like R-12 all over again......take away what works and give us CRAP in replacement! It sucks knowing that I'm old enough to remember when you could jump in a car and have it cool off within a couple of minutes...