I'm leaving out the various conversations from contributors just to not get
in a ****ing match :{))
Richard Kollmann, a reasonably respected marine refrigeration guy, has been
playing this tune for quite a while.
The overheat function is supposed to be in the controller which, if IT'S
cool enough, won't do anything. If the outgoing gas (with minute traces of
oil in it, of course) gets hot enough (as apparently it did, based on my
having to replace an o-ring on the high pressure connector), it doesn't have
to be in the compressor to change state, either. So, unless whomever your
builder is had put in a sensor IN/ON the compressor, an overheat might well
be missed.
The bottom line, for Frigoboat (my new system ducts its air over the
compressor, and based on my small test of using the fan in the supplied air
cooler, alone - no refrigerant cooling in that unit - blowing on my
compressor resulting in a significant drop in temps, that will eliminate
even the *possibility* of overheat), is that the tiny heat sink and tinier
fan they use is insufficient, regardless of circumstance.
I base this on the temps achieved in the compressor with all three possible
connections - keel or air cooled alone, and both in tandem - of condensor.
That, with the air alone, resulted in very high temps at the compressor and
input line, but ambient temps at the output line of the air cooler. So,
with entirely adequate cooling of the output gas, the compressor and output
line were still in the range of overheat.
My new system is different in several significant ways.
First is that it's not a capillary tube-based system. That leads to the
second, that the smallest diameter line is 1/4" compared to the cap tube's
hair-width diameter (I don't know what it really was, but the outside was
about 1/16"). That cap tube, the evaporator-mounted
filter-drier/accumulator and ends of the suction line at the evaporator have
been sent off to Richard for his testing (he's been scratching his head for
years at Frigoboat failures).
Also, our new system has a filter-dryer-accumulator, with a sight glass.
That volume is massively more than the combined cap tube filter and filter
dryer which were sent by Frigoboat in trying to resolve our problem. So,
not only will I have a visual means of seeing charge state, the volume
makes it less sensitive to exact amounts, as well as providing a relatively
huge level of filtration/drying. I've been advised that unless the system
is opened (no quick-connects in this system), there's never going to be a
need to replace/refresh this.
Our system will have a (manually adjustable) valve which controls the level
of refrigerant return/input to the evaporator(s - we have two, now, which
ALSO will be more efficient due to the 8-sides available for air
circulation, rather than our bent plate's 4) rather than the cap tube, at
1/4" and not subject to fouling even if there WERE contamination. Which is
extremely unlikely because...
The system is comprised of a sealed box. The cooling fan on the condensor
either pulls or pushes air over the compressor, depending on the fan
orientation. In our case, it will be vented to the outside, in order to
dump heat from the engine room where it's located, rather than pulled in
from outside, so as to avoid salt-laden air. As our engine room is
reasonably well sealed, the incoming air will be traveling through the
bilge, the coolest place on the boat not refrigerated. In any event, this
unit has been proven successful even in 100° air - and, if I should ever
care to add it, is capable of water cooling, as well. However, given the 1A
draw on the pump, it would have to be in very cold water for the extra heat
dumping to be energy efficient. As we don't expect to spend any time in
that environment, likely that will remain only a sales point for whomever
buys the boat after we're off.
Finally, not related to the above, I was able to easily get out the
evaporator. All my heat-gun defrostings had made the adhesive of the
stainless plate easy to separate, and that folded into a third (on the bends
we used to make the 40" plate fit our box), which fit through the freezer
door opening. The evaporator was even easier, being aluminum. So, in the
end, getting the old system out was much easier than expected.
The new system was expected to be two 15x19 plates, but an error due to a
quickie measure meant that they wouldn't fit on the sides, by about 1/4" (my
supplier used a tape measure, and didn't allow for the bend, or something,
and the slight tapering of the box at the bottom), and so we now are waiting
for the arrival of a 14x19 plate, with the other 15" being mounted to the
hull-side wall, as being big enough. The usual design parameter is to place
the plates on opposing walls, but our installer felt that getting the extra
cooling outweighed the disadvantage of adjacent plates. As it is, he had to
use the smaller size because, while he COULD have ground down the mounting
edges to allow it to fit it would have been hard on the other plate, losing
two sides of air circulation behind the plates. So, while he DID do some
grinding, he quit when he saw how they'd lay together, in favor of the
increased air movement. As we STILL had/are having to wait for another part
to come, I wish that he'd abandoned it immediately rather than drilling the
holes in the hull-side wall, and gone for the slightly smaller plates
entirely, returning the two he ordered before cutting into the tubes and
attempting grinding of the edges to make the second one fit. But, it is
what it is.
As it is, since the new compressor is a BD80, it's got ample horses to pull
out the BTU, so it's probably all pretty academic, other than perhaps the
amp draw, as this system's lowest speed is half again the amps the BD50 it
replaces.
A small annoyance is that this system has its own smart/manual controller
with an integrated Carel thermostat, which we already had for the freezer,
so I now have a spare for my other Carel, which controls the spillover fan,
and, as the Frigo compressor is presumed inalterably contaminated, a spare
controller, to go along with a spare smart speed controller, as well. The
good news is that it's now going to be right next to the reefer's Carel, so
we can see the state and/or alter to manual control if we care to (we never
did other than in the testing we were doing for the Frigoboat) without
having to peer into the engine room.
It's not yet installed, but I have every expectation that it will work as
it's supposed to, out of the box. More when it's finished.
L8R
Skip
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Morgan 461 #2
SV Flying Pig KI4MPC
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