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Subject: Re: TWL: Refrigeration/cold plate question
From: Robert Austin (thataway4@XXX.XXX)
Date: Thu Jan 03 2002 - 21:07:39 EST
Darby,
We have built three different installations using eutectic holding
plates.
They work very well and are very efficient. Perhaps the most important
feature is that there is effective insulation (vs. the small amount in the
Norcold type of units). There is also no heat generated near the box. The
compressor is remotely installed. We found that an hour or max two a day
sufficed when in the Pacific North West, and up to four hours a day in the
tropics where the ambient temperature was up to 100 degrees.
The first unit was using a Sanyo Auto Air-conditioning compressor with a
Sundur water cooled heat exchanger. There was a single "Dole" galvanized
cold plate in the freezer unit, with a bleed over, and small fan operated by
a thermostat in the refer unit. The outside insulation was 4" of closed
cell foam, including the lid. The separation was between the refer and
freezer was 2" closed cell foam. The interior was fiberglassed and gel
coated.
The second unit used a 3/4 hp 110 V air cooled compressor only. This was
both water and air cooled. There was a 12 cu foot refer with front opening
doors and about 2" of foam insulation (this was already in the boat) The
door seals were doubled and a cam type of latch was utilized for a very
tight seal. The freezer was also 12 cu feet--a chest type, top opening,
with 6" of foam insulation on the sides and 4" on the top. Both of these
had two Eutectic plates made of SS. The freezer plate was rated at 0
degrees and the refer plate was 25 degrees.
The third unit used a Techanutics water cooled compressor and dual system
plates for the engine driven portion. I used a Flemming water and air
cooled. Compressor for the 110 volt circuit. There was a thermostat which
shut off the compressor for both the 110 volt and engine units. The two
plates were rated at 0 degrees and placed in the freezer (six cubic foot
freezer and refer). There was a bleed over, with a small fan operated by a
thermostat in the 2" separator between the refer and freezer (this separator
was Formica over foam. There was a top load on the freezer and a top load
and a low front door (for the bottom) on the refer. There was about 4" of
foam all around the units.
When I was able to, I first laid down a heavy aluminum foil reflective
barrier, then a 12 mil poly prop membrane, and then the foam. The inner
surfaces were covered with fiberglass, gelcoated on the inside.
There were no voids in the foam.
In the last unit I installed a 12 /110 volt norcold "L" shaped unit to give
refer at the dock side, when I was not on the boat to run the freezer unit.
Another self contained unit to consider is the Nova Kool. This appears to
be a slightly better unit than the Norcold at comparable price.
Bob Austin,
30 foot single diesel aft cabin Carver
Pensacola, FL.
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