Hi, Glenn, and thanks for the response.
My expected pattern will be on the hook for extended periods of time,
particularly in the high season, when I/we expect to be working, perhaps 7
days a week, long hours. Since part of the reason for going offshore for
the rest of my life is peace and quiet, running engines or generators isn't
very appealing, and so I expect to have substantial solar and wind
generation to minimize that. Of course, once under way, there will be
enough instances of running the engine, I expect, that it won't be of issue
very often.
So, I'm anticipating doing something using 12V, if for no other reason than
greater efficiency than having to turn it into 120V, when I'm not running
some IC power source. I'm currently open on the subject of (IC[diesel - I
don't think I'd consider gas]) generators, but nearly certainly would not
buy one if it didn't come with the boat we buy. But, if we had one, likely
I'd like a combo ability (12V/120V), perhaps even with a tie-in to an
engine-driven compressor if it's cold plates we use.
Have you done any calculations on the load required to run cold plates
(daily amp hours) vs evaporators for the ability to keep a given volume to a
given temperature? One of the boat types we've considered has an example of
a refit set of evaporators, so it has me thinking... (They wrapped it
around the previous freezer section, entirely, at the top, and had a box/lid
topmounted in the previous reefer space, each having their own knob
temperature adjusters. I don't recall the brand, but there were two
compressors in the engine room, backed up against the reefer/frig space.)
Thanks.
L8R
Skip (and Lydia)
--
"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail away
from the safe harbor. Catch the trade winds in your sails. Explore. Dream.
Discover." - Mark Twain
"Glenn Ashmore" wrote in message
news:UFoDb.5096$JD6.3998@lakeread04...
Richard may have a different view but IMHO, (and you know what that is
like because everybody has one) it really depends on how you plan to use
the refrigerator. Holding plates take a lot of energy for a short time
and evaporators take a little energy for a long time.
Many blue water passage makers still prefer holding plates because they
fit into the daily energy routine. Coastal, island hoppers and marina
queens prefer evaporators. Production boat builders much prefer
evaporators because they cost a lot less, the box can be made a lot
smaller and lest we forget, they are always selling to the first mate,
not the skipper.
With the introduction of the higher efficiency Danfoss compressors and
especially that new Glacier Bay unit, I think that holding plates
require more total energy per day but it can be made to run when the
engine is running and energy is cheap. Holding plate systems seem to be
a lot more ruggedly constructed and can be configured to fit a wider
variety of boxes and usage patterns. They use fairly standard parts so
they can be serviced by most refrigeration techs. Evaporator systems
are more unitized so service is a bit more difficult.
Holding plates have a couple of down sides. First they take up more
room in the box than evaporators and you will have a wider variation in
box temperature with holding plates which is not good for long term food
storage. Evaporators can maintain a more even temperature but you have
to invest in more batteries to store the required energy. Evaporators
can also maintain the temperatures during longer absences from the boat
if you have alternative charging sources like a wind generator or solar
panels.
Evaporators are a lot simpler than holding plate systems. Most have
capillary tubes rather than expansion valves and often come pre-charged
so installation is a lot easier. They also have to disburse heat at a
slower rate than holding plates that have to remove a whole day's worth
of BTUs in an hour or so. That means the smaller ones can be air
cooled and the larger ones require smaller cooling water circuits.
Evaporator plates are almost totally machine made while holding plates
take a considerable amount of skilled labor.
Skip Gundlach wrote:
Well, not air conditioning...
In reefers and freezers, I've been fonder, by far, of cold plates.
OTOH, in
my most recent trip, a broker who sells new boats asserted that nothing
comes out of factories that way any more due to greatly increased
efficiencies in current equipment, making 12V on-off, thermostatically
controlled, refrigeration and freezing more appropriate, not having to
run
the engine or genny, etc. In an unrelated, other than efficiency,
matter, in the second most recent trip, I was also aboard a boat with
12V AC
which was in the dehumidify mode, and was quietly purring away in the
stern
lazarette, seemingly not using much power, which might support the
position.
So, back to refrigeration. Anybody know that to be gospel or hooey?
That
is, is there hard (vs scuttlebutt) info which supports or refutes his
position?
Glenn? Richard? Others in the trade?
And, assuming tired stuff where/whatever it is, how expensive is it,
relatively, to refit one or the other (replacing what's there)?
Thanks.
L8R
Skip and Lydia, rounding third, post on that to follow
--
Glenn Ashmore
I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com