On Aug 28, 6:29 pm, "Karl Townsend"
wrote:
After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?

Karl

I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan