Jeff wrote:
Again, this may be true, but it might not be appropriate for all
systems. Adding a thru-hull and more components probably isn't worth a
few Amp-hours savings.
From Richard Kollman's site:
28. Question: Why would I want air cooling when water is more efficient?
Answer: Boat refrigeration systems smaller than ¼ HP are generally air
cooled for best performance and long term reliability. There are few
conditions where the seawater cooling can out perform air cooling on
these small units. To dispose of the heat in a boat from a small Danfoss
refrigeration system is about the same as disposing of the heat
generated from one person onboard, three hundred BTUs per hour. It is
true that heat from larger refrigeration systems must use seawater
because the heat can not be disposed adequately of onboard a boat.
http://www.kollmann-marine.com/answers.html#28
And, what kind of pump is only a half Amp? Most of the circulating
pumps for DC belt driven systems seem to take an Amp or more. The
traditional March 809, for example, is rated at 1.5 Amps. Of course,
the pump for a Danfoss system could be much smaller.
Doug Dotson wrote:
The water pump on my system draws less than 1/2 amp. Using a water-cooled
system saves enough energy to more than offset the overhead of the pump.
Doug
"Jeff" wrote in message
...
It may be true that water cooled is usually more efficient, but for a
minimal system based on a BD35, the added efficiency may not be worth
the power use of a water pump. This is a small issue with a large
holding plate system because it only runs one or two hours a day, but
the small evaporator based system may run 8 hours a day, and the
water pump would then add a lot of overhead. And, it adds a
through-hull, strainer and plumbing, and can get clogged with silt.
This may be worthwhile Downeast, where the water is 52 degrees, but
might not be in the tropics.
Doug Dotson wrote:
A water-cooled unit is always more efficient than an air-cooled
unit. Unless
somehow the air temp gets cool for a long period while the water
temp stays
high. Not very common. This is why all the larger units are
water-cooled.
Doug
s/v Callista
"Jeff" wrote in message
...
A lot depends on the size of your fridge and how you use it. If
you can go into a bit of detail, such as the size of the box(es),
freezer requirements, and the nature of your cruising, you might
get better advice. For example, if you cruise in cold water, a
water cooled system would be more efficient. But if you power each
day (or run a genset for A/C) then the power issues might not be
important to you.
I have larger Crosby (actually part of A/B) holding plate system
for a separate fridge and freezer system that I've had a love/hate
relationship with. When I pull a steak out of the freezer that's
frozen down to zero degrees, I'm happy. But when I don't need the
freezer, its a real annoyance to use 70 to 100 Amp-hours a day on
the system. And of course, one small leak and the whole system is
down. (This happened twice in 7 seasons, and both times was
detected in home port, not while traveling.)
If I were building my system now, I might consider having two
systems based on the new Danfoss compressors. While perhaps not
the most efficient in total, having two systems for the two boxes
would give more flexibility in case one is lost.
Danfoss is the "hermetic" sealed compressor your A/B is based on,
and is used in most of the smaller systems today. Of course, the
units have changed in the last 20 years, and each company has some
"special technology" that makes theirs the best. You might look
over www.rparts.com to get a free education about the components in
use today. They carry the latest Danfoss units and this will give
you a baseline to see if you're getting your money's worth from
whichever system you decide on.
Dick Behan wrote:
The 20-year-old Adler/Barbour unit on our Victory Tug has expired.
Can't complain about the service, but what do you cruisers out
there think about replacing it? Go with Adler/Barbour again, or
is there a more up-to-date technology (and product) you'd
recommend as superior?
TIA.
Dick Behan
M/V ANNIE
My little electric frige has a warm plate at the rear, more or less
surrounded by cabinetry. My engine room vent inlet passes nearby.
I wonder if venting the warm plate to the vent pipe using a dryer
air box switch might provide some benefits during warm or even cold
weather, depending on the airbox switch?
First, would such a vent improve the efficiency of my frige?
I am presuming that the engine would suck in the frige heat without
any complications, and that there is enough rise in the intake side
for when the engine is asleep. Hmmm.
Would I benefit from blowing a fan into the open frige on a hot
night? Maybe cooling down just for long enough to doze off in the
saloon table hammock?
Terry K