On Fri, 25 May 2012 14:43:56 -0500, Jon Elson
wrote:

Tom Gardner wrote:

Is it a good or bad idea to change over to one of the new refrigerants
that claim lower head pressure, cooler air and substantially reduced
electricity usage?
Change over, as in replacing the whole system, or change over as
in just putting a different refrigerant in the same system?
The former is expensive, the latter almost certainly won't work.
Each system is designed for a specific refrigerant, and with a few
exceptions, can't be converted to use a different gas. The thermodynamic
properties of the different gases are very different, requiring different
compressor displacement and compression ratio, as well as often changing
lube oil.

Jon
Switching MOST automotive systems from R12 to R134A works quite well
with no changes to the system, except blowing out the old oil and
installing the compatible oil.

There are many "universal" replacement refrigerants out there that
work, with varying efficiency and satisfaction, in different systems.

Many refrigeration systems are NOT optimized for the refrigerant
originally installed - so a somewhat different gas MAY actually work
better. It may also work somewhat worse. Or even a LOT worse (or
better).

It is a crap-shoot using a non-specified gas - but it really isn't
rocket science. If it is marketed as a replacement for R20, it LIKELY
will work reasonably close to what the R20 did. You do want the vapur
pressure, specific heat, etc to be reasonably close, which is why you
don't exchange R12 for R20, or vice versa.