engine-driven fridge
 

Alas, most of our problems have been caused by 'professionals' and
'experts'. I'd guess we've put at least $5000 into this system over
the last couple of years, most of it in $50/hour or more payments for
guys who claimed to be experts standing around waiting for the plates
to cool. And what we got for it in the end was a system that ran for 4
weeks before breaking. One guy put in a new high-tech gas that was, of
course, incompatible with the R134a oil already in the system. (That
cost us a bundle to put straight.) Another simply removed the
accumulator, saying that nowadays that's no longer needed (another
bundle, including paying for 2 new compressors in as many days.) That's
when we decided to take over, even if we don't know that much. How can
it possibly cost us more than the experts do?

And of course, now we've got you-all to keep us on the straight and
narrow. :-)

Rob

engine-driven fridge
 

On 24 Aug 2006 09:56:02 -0700, "Akka" wrote:

Alas, most of our problems have been caused by 'professionals' and
'experts'.

If you really have to do it yourself I'd recomend that you start with
a copy of Nigel Calder's book: "Refrigeration for Pleasureboats:
Installation, Maintenance and Repair"

You can get it from Amazon.com

http://tinyurl.com/fa693

You will also need a set of pressure guages, vacuum pump, leak
detector, temperature guages, IR temperature gun, small vacuum cleaner
and a few other specialized tools/supplys.

Most of the tools and supplys are available from Grainger:

http://www.grainger.com/Grainger/wwg/start.shtml.

engine-driven fridge
 

On 24 Aug 2006 10:13:38 -0700, "Akka" wrote:

And my wife will be SO grateful!

You bet, and that's important. :-)

engine-driven fridge
 

Thanks for the advice and links, Wayne! As it happens, we already have
Nigel Calder's book, which we always pick up and pore over any time we
have a new mechanical or electrical problem. It's incredibly complete
and useful -- can't imagine how we (or any other creuisers) could do
without it. We definitely read the section on refrigeration, and
learned a bundle.

Unfortunately, that appears to be what got us into our current problem,
as Calder was (I guess) writing with R12 in mind. It's because of him
that we filled the system until the sight glass was full, and
apparently overcharged. Also, he gives a table for ambient temp vs.
refrigerant pressure for R12 but nothing for R134a -- and it turns out
you can't use his table for R134a, even as a SWAG.

We finally bought the gauges but didn't think a 220V vacuum pump was a
worthwhile investment as we'll be returning soon to the 110V world. If
we open the system, we have to borrow or rent somebody else's pump. We
judge compressor and return-line temps by feel -- in the former case,
if you can touch it without burning your fingers it's not too hot, and
in the latter if it's cold but not frosting it's not too cold.

Rob

engine-driven fridge
 

My edition of Calder's book (printed 1994) has the r134a table and
several other hints in the front as an "Ozone alert and update." You
can certainly find a table on the Internet:
http://dodgeram.org/tech/repair/HVAC/R134a.htm

I'm not sure measuring the high pressure side temp by touch works
well, because you'll be reading the temp of the compressor itself. My
pressure line is pretty hot, but the guage says the temp is about 90
degrees (about 20 degrees above the cooling water).

You might consider getting (or at least looking at) the latest edition
of Calder's larger book, The Mechanical and Electrical Manual. It
has revised advise on refrigeration, based on the latest technology.

Akka wrote:
Thanks for the advice and links, Wayne! As it happens, we already have
Nigel Calder's book, which we always pick up and pore over any time we
have a new mechanical or electrical problem. It's incredibly complete
and useful -- can't imagine how we (or any other creuisers) could do
without it. We definitely read the section on refrigeration, and
learned a bundle.

Unfortunately, that appears to be what got us into our current problem,
as Calder was (I guess) writing with R12 in mind. It's because of him
that we filled the system until the sight glass was full, and
apparently overcharged. Also, he gives a table for ambient temp vs.
refrigerant pressure for R12 but nothing for R134a -- and it turns out
you can't use his table for R134a, even as a SWAG.

We finally bought the gauges but didn't think a 220V vacuum pump was a
worthwhile investment as we'll be returning soon to the 110V world. If
we open the system, we have to borrow or rent somebody else's pump. We
judge compressor and return-line temps by feel -- in the former case,
if you can touch it without burning your fingers it's not too hot, and
in the latter if it's cold but not frosting it's not too cold.

Rob


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engine-driven fridge
 

On 25 Aug 2006 00:38:34 -0700, "Akka" wrote:

Unfortunately, that appears to be what got us into our current problem,
as Calder was (I guess) writing with R12 in mind.

Yes, and every refrigerant has different properties.

It's because of him
that we filled the system until the sight glass was full, and
apparently overcharged. Also, he gives a table for ambient temp vs.
refrigerant pressure for R12 but nothing for R134a -- and it turns out
you can't use his table for R134a, even as a SWAG.

That is correct.


We finally bought the gauges but didn't think a 220V vacuum pump was a
worthwhile investment as we'll be returning soon to the 110V world. If
we open the system, we have to borrow or rent somebody else's pump. We
judge compressor and return-line temps by feel -- in the former case,
if you can touch it without burning your fingers it's not too hot, and
in the latter if it's cold but not frosting it's not too cold.

You absolutely can not properly adjust the system by feel. I'm
fortunate to have a neighbor who makes his living as a refrigeration
specialist. He has a detailed set of tables for each type of
refrigerant and uses electronic temperature guages in conjunction with
the tables and pressure guages to adjust the TXV. I used another
specialist in the north east to install the freezer. He used exactly
the same approach.

engine-driven fridge
 

That's amazing. Not one of the 6 or so 'experts' we've had on board
(even back in the States) measured temperature.

Live and learn.

Rob

engine-driven fridge
 

Gee, we have the same edition of Calder's book that you do, obtained
_last year_ from Bluewater Books, and there are no such tables there.
Thanks for the helpful link, though.

Cheers,

Rob

engine-driven fridge
 

Akka wrote:
Gee, we have the same edition of Calder's book that you do, obtained
_last year_ from Bluewater Books, and there are no such tables there.
Thanks for the helpful link, though.

Cheers,

Rob

Sounds like you might have gotten very old stock. I got mine maybe 6
years ago, but if I look at Amazon it shows up in the Table of
Contents for the version they currently ship. You might look on page ix.




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engine-driven fridge
 

On Sun, 03 Sep 2006 18:13:58 -0400, Jeff wrote:

Sounds like you might have gotten very old stock. I got mine maybe 6
years ago, but if I look at Amazon it shows up in the Table of
Contents for the version they currently ship. You might look on page ix.

Yes, I have the same version. In my book the table for R134a is
actually on the back side of page ix, just prior to page 1.