From: John De Armond
Subject: Re: do it yourself
Date: Tue, 27 Jul 1999 02:26:50 EDT
Allan Adler wrote:
> Well, ok, my first question is this:
> what is the simplest cool temperature-controlled unit I can set up
> without previous experience and without breaking any laws or treaties?
> My second question is: what book, aimed at beginners, would explain
> how to do this and guide one through the construction?
> Just to give an idea of the level I have in mind, there are
> metal working books by David Gingery which tell you how to build your
> own lathe from scrap aluminum and which guide you through the
> construction, starting with building your own foundry.
I'm kinda of a Gingery fan too. Started casting aluminum before I
got his books but I've learned a BUNCH from them. Unfortunately I
don't know of anything printed like that for refrigeration. If you
go back and do the dejavue search I mentioned earlier, you'll find a
lot of experimental stuff written up as Usenet postings. George and
I met because we were both refrigeration hackers and were both
working in parallel (unbeknownst to each other) on a grassroots
solution to the freon ban. George went on to make a commercial
product and I went off to do some things that didn't make much money
Anyway, the first thing you need to do is to get yourself a
refrigeration handbook. There are several titles out there. One I
like is "Modern Refrigeration & Air Conditioning". All the
different titles I've seen have a lot in common, they're large,
they're heavy, they're comprehensive and they're moderately
expensive. Most refrigeration wholesalers carry one of the titles.
I recently saw one in the Science department of Barns & Nobles
(store, not the web). These books are aimed at the service
technician. Some people might recommend the ASHRAE handbooks but
IMHO, they are too advanced for a beginner.
You should also look for old books. I collect old refrigeration
books. 50+ years ago, a refrigeration operator or service man was
expected to know everything about the systems he was responsible for
and was expected to repair compressors and other components and not
just change out parts. Many plants were still manually operated.
That is, an operator started and stopped and/or loaded the
compressor by hand and the expansion device was an ordinary
refrigeration globe valve that had to be set by hand. I have one
old book that covers nothing but the operation of a manual ammonia
plant! Audel used to publish a series of books on refrigeration,
electricity, carpentry, etc. I have an old set of Audel
refrigeration books and like them. One nice thing about old
refrigeration books is you usually pay, oh, 50 cents or so for 'em.
Not exactly collector's items.
One of the first things I did when I was starting out many years ago
was to set up a fully manual refrigeration system. Found an old
chest freezer that still used a condensing package with service
valves. Stripped the condensing unit out and set it up to freeze
homemade ice cream, as it turns out. Nothing like the anticipation
of homemade ice cream as one sits there carefully watching the
suction pressure and temperature while tightening down on the
expansion device/needle valve! I've even made glass evaporators and
condensers so I could see what was going on inside. Of course, back
then R-12 was 20 cents a pound and available at K-mart and you
didn't really care if you popped a load after some screwup.
R-22 is probably the easiest refrigerant to work with today. Still
pretty cheap, low ODP (if you believe that matters), minimally
controlled by the EPA and can be replaced with propane if you don't
want to get a green card. An old window air conditioner is a good
place to start. Runs on 120 volts, rugged compressor and
self-contained. You can recover the R-22 using a salt-ice bath and
a suitable container and then reuse it to play. Though they won't
last forever when run this way, you can get away with running a
window AC compressor at pretty low temperatures and pressures long
enough to experiment with it. If you decide to use propane, use the
propane torch cylinder gas. Gas grill gas (or other bulk-sold gas)
is too wet for refrigeraton use.
One of the neat things George did back when they were first starting
out on the trade show circuit was to use copper tubing to bend up
the letters of his product name - kind of like neon - then connect
it to a condensing unit and put the letters over his booth. With
the condenser unit running, the tubing would frost up and look like
The handbook will show you what kind of tools you'll need. You
don't need them all at once, of course. In terms of test equipment,
a set of gauges, a good digital thermometer, a DVM and a good
amp-clamp will get you going.
get your handbook, read up and then ask more questions.