Tom Gardner wrote:



I've heard about using propane. AND I've heard the new refrigerants are
similarly petro-based and flammable. Is there an energy savings?
Really, different refrigerants don't have vastly different properties
in respect to energy required to move X BTUs from temp 1 to temp 2.
There are differences, and Propane is a bit better, but the difference
is pretty small. I used to have a thermodynamic calculator program
where you entered all the parameters (temp 1, temp 2, heat load,
compressor displacement, and refrigerant) and it would calculate the
HP required. It did show Propane to be a bit better than R-22.
But, the possibility of a major leak indoors blowing my house up
for the small improvement in efficiency made it seem like a bad idea.

Now, the newer A/C units achieve all their higher efficiency through
other means. They often have variable-speed compressors, scroll
compressors are a bit more efficient than pistons and valves,
they almost all use thermal expansion valves instead of capillary
metering, and they have larger condenser cores so that the condensing
temperature is a lot lower. All of this helps improve the
efficiency. just cleaning out the condenser core with a garden
hose can reduce power consumption 20% or more, and of course can bring
a system back to life when it is packed with cottonwood fuzz.
I clean my condensers once a year, for sure.

So, if you think the secret of the high SEER ratings on newer units
is due to the refrigerant used, it is practically achieved DESPITE
the refrigerants they have to use due to the ozone problem.

Jon