* Wilbur Hubbard wrote, On 8/10/2007 9:15 PM:
....
However, a 30 Amp draw is quite common for my type of fridge. Its a
1/2 HP motor driving a compressor that feeds several holding plates in
a 9 cu ft fridge and 5 cu ft deep freeze. The actual load varies from
20 to 35 Amps. Here in Maine I've been monitoring it carefully, and
it has taken about 40 Amp-hours per day for the last two weeks. The
fridge stays at 42-46 degrees, the freezer at 15-20, both measured at
the top shelf.

What you're doing is pretty wasteful.

It was installed before the current high efficiency Danfoss unit were
available. However, it still seems more efficient than yours.

Sounds like you have a separate
freezer and refigerator. That's dumb. All you need is a freezer that
connects to your fridge box with a well-insulated duct. Keep your
freezer full of meats and other dense stuff and run it all the time.
Allow some of the excess cold air to migrate into your fridge box by
controlling the size of the duct. The duct should run from the top of
your freezer box to the bottom of your fridge box. If you do this, you
could run the entire system on one modern, efficient Danfoss compressor.

Spill-over systems have some virtue. However, that requires a
particular geometry that can't always be achieved. Also, its rather
doubtful that one Danfoss could chill a system as large as mine. Even
if it could, I would still split it into two. There's a huge
advantage to having redundancy and being able to scale down so a boat
could be left unattended for moderate periods.

Holding plates are a stupid system because they are bulky and take up
too much room inside the ice box.

They take no space at all; their volume is not included!

Better to have a flat or box-shaped
evaporator and use meats and other dense frozen foods as the holding
plate. What I do is completely fill the freezer part with canned beer.
The Ice beer works best because of the high alcohol content it doesn't
freeze and bust open. But, the thermostat cant' be set to the cold
position. About 1/4 the way to all the way cold works best. My freezer
contains 15 twelve ounce beers.

That's a pretty small freezer.

I relpace them one at a time as I drink them. I maybe drink six on a
hot day. I cycle new beers from the fridge
section to the freezer section and add new ones to the fridge section as
I drink them. An admirable holding plate.

In other words, you open the freezer at least six times a day? And
your antifreeze consumption certainly explains the quality of your posts!


My box is very-well insulated and because of it my compressor usually
runs 20 minutes on 40 off in the summer and about 15 minutes on and
close to an hour off in the cooler months of winter. Let's call that
one-third of 24 hours for 8 hours total or 40 amp hours. The box
measures about 1.5 feet by 2 feet by 1.5 feet. For about 4.5 feet cubed.

That's about a third the size of mine combined boxes, which also is
using 40 Amp-hours a day. And the warmest spot in my freezer is 20
degrees. Even in the tropics, serving three people, we rarely went
over 90 Ah a day. And that was before I learned how to maintain it
myself.

It and everything else is run by two Evergreen 100 watt photovoltaic
arrays connected to a Sunsie charge controller. The fridge runs more in
the summer months but the days are longer too so the batteries stay
well-charged the year around.

Adding more solar is high on my priority list.

... If you have the room, one
foot of insulation all around is the way to go.

My freezer has 7 inches all around, including the top. This biggest
issue now is that the seals have degraded, so they now let in too much
humidity. The fridge insulation is more important as you move south
and have higher temperature differentials, and hot nights. My fridge
alone can get by on as little as 15 Ah a day when a cold front comes
through!