Frigoboat catastrophic failure and attempts to start over...

[redsky49]

Some suggestions:

Having retired from a mechanical engineering career, I would approach this as I would any refrigeration project, and would first start with a load calc. What is the calculated load? And the answer is :

Q = U x A x Delta T, or load equals (transmission of heat through your insulation or assembly ) x (surface area of the insulation/assembly) x (cooling load temperature difference or delta T).

You should have some idea of the anticipated load in order to assemble the proper components of the system and to evaluate the performance once installed. This is not something that should be guessed at or assumed due to "rule of thumb" estimations.

I'll leave the original below for reference, as it's an old thread. It's so
old you might want to skip down to the attribute-marks section ([ ">" in
front of each line] to get a basis point, or if you'd not seen it, to get a
clue; the masochists will read the entire referenced thread in CF) before
reading further. It covers my removal of a previously very satisfactory Frigoboat system and replacement with a Sea Frost air and water cooled system...

So, in the end, there were 3 11x16 SS clad evaporator plates, in series,
through a constant-pressure control (functioning like an expansion valve),
running through a large evaporator-dryer, with sight glass, to a BD85 air
and water cooled compressor, all from Sea Frost.

This is the first area of concern, as series evaporators can be challenging. Wasn't a single evaporator available/possible? Was this the recommendation of the supplier, Seafrost?
The BD85, of course, has a higher capacity than the 50 it replaced, but at a
large cost in electrons. Low speed (there's a controller similar to the SSC
of Frigoboat, with, perhaps, some more smarts, as I don't know the specs of
how Frigoboat's unit manages the speeds, but the specs look impressive)
pulls 6A, the same as high on the 50. Ergo, at low, it should be removing
as much heat as the previous system did at high (watts = amps = BTU
removed).
Who selected this size compressor and on what basis?

The Frigoboat system did an admirable job while it was working. I could
take it to an indicated 0° in the freezer (control used box temp), far
colder than I needed, and still have it not running at full speed once the
temp had been reached.

Unfortunately for me, including the addition of the water cooling (another
complexity made unnecessary by the keel cooler in my Frigoboat system) by my
installer, Clay Hansen of Hansen Marine in St. Augustine, the system still
isn't right. As the initial installation had several defective components
(two temperature probes and the constant pressure valve) Clay gave it some
serious tweaking for about a month, while we were off the boat, and declared
it fit. On Christmas Eve 2013, when it wasn't hot, ever, it was working,
and we headed south. But...
It's unclear how this heat rejection is arranged. Is it user selectable for either air or water cooling? How is this piped?
It's voracious for electrons, and even at low speed, runs about 80% of the
time to achieve a box temperature in the 10-15° range, controlled by plate
temperature, the probe being at the bottom of the last plate. The
refrigerator, as it's fed from a spillover fan, continues to maintain its
temperatures satisfactorily, but at the cost of the freezer continually
having to run. Sea Frost's computer, if you let it run it (automatic
setting), looks for a 52% run time. Without a great deal more than the 6.5°
hysteresis recommended, there's no way possible to achieve that ratio on the
computer controlled version - and a higher gap would mean much more box temp
variation, something I'd become accustomed to not even thinking about, with
my previous (box temp) hysteresis of 2° - and to do so would be unacceptable
to me in any event.
I am unclear what you are referring to by hysteresis.
Worse, after a decommissioning during a month-long trip ashore (I was on a
mooring and didn't dare leave it running), the third plate was only about
half frosted, with the compressor running non-stop, whereas before, it had
been complete, with the frost line ending an inch or so into the plate
before the return line to the constant pressure valve.
Do you have any empirical data on the suction side (return line)/liquid side (supply line) temps?
The Sea Frost owner, Cleave Horton, in my followups recently, had me fiddle
with the CPV, which resulted in an immediate frosting of not only the plate
but the return line (too much), and subsequent fiddlings have it back to
where it was, with the entire 3rd plate frosted, but the return line not
only very cold but almost frosted. Probably a pretty good place for it.

But that's with my having - at Cleave's strong suggestion - increased the
plate temp for shutoff by 2.5°, to 5°. So, I now have a warmer box, and
still about an 80% run time at low. I can jack up the speed and have it run
for shorter periods, but at a larger amp consumption. My expectation is that
running essentially full time, assuming the temp stays at the level you want
it to be (the function of the smart controller, rather than leaving it on a
given speed), is the most efficient. However, Cleave suggests leaving it at
low full time for the least amps used.

At that rate, based on no-wind nights, and next to nothing else on (2 0.1A
fans and breaker panel overhead), we're averaging 8 amps or higher just for
refrigeration - at night, when it's cooler. I can't support 200AH daily
loads, with added daytime (more heat, more stuff running, boxes being opened
occasionally) loads with my wind and solar unless conditions were absolutely
perfect - all bright sunny days and consistent winds of 15 or higher. The
amp draw is pretty consistent, whether on "automatic" - the equivalent of
the SSC in Frigoboat systems or "low"; we had one night of unexplainable 3A
average, and a couple of 12A average, but otherwise it's been in the 8A or
fractionally higher range overnight; this over more than 3 weeks of
observation.
Unclear. Are you saying that overnight energy consumption is 8A at 80% runtime per hour (6.4 ah)?
After several emails back and forth, and several phone conversations, the
best Cleave could come up with was to play with the CPV, and "good luck" for
recommendations. This, despite his own manuals cautioning against lowering
the temps into the double-digit negative zone instead of merely to zero, was
accompanied by the assertion that 8° was way too cold, and that something
closer to the low to mid 20s was ample for freezing. Maybe if you're going
to rotate your stock on a daily basis, but that doesn't ring true for
anything resembling longer storage, let alone whether whatever it was you
wanted hard frozen would melt 5 minutes out of the freezer. As this system
cost, all-in, half more than the comparable (air cooled with keel cooler,
added filter-dryer and full wrap-around evaporator) Frigoboat system in
cost, this is most distressing.
As an aside, freezer temps are not sufficient at 20 degrees F for extended food storage. Required temps vary with the type of product stored, but for safety should be closer to 0 degrees F.
Better yet, the metal screen filter in the water cooling installed (a Groco
WSB-500) started to disintegrate almost immediately, never mind its being
clogged and requiring frequent cleaning. So, for a small time, we ran it
without the water cooling. There was no chance. Temps in the freezer
remained in the mid to high 20s despite the system running full time.
Likely I'll replace the metal one with plastic, assuming I can source it
(how many times does a filter media fail?? - not much in the way of stocking
dealers), but it's just another annoyance. In the meantime, we're running
the pump, as we have a dome filter on the exterior, left over from when this
boat had air conditioning, and Cleave assures me that if it can't get
through that, the pump will happily move it along. Update since I drafted
this; I got new plastic filter media from Groco - a much larger mesh - and
sure enough, the flow improved greatly. Without the water cooling, our
system doesn't stand a chance in S. FL; it MIGHT be ok with air alone in
cold water and cool temps. However, here in Vero Beach, this last time we
took it off (only a few days' worth of running) to swap out the media, there
were 3 small barnacles on the housing. If those get into the cooling pipes,
we're dead. Obviously, whatever it is that barnacles start out as can fit
through the dome filter outside; I'm not sure that the plastic media is much
smaller. There isn't much dead time (no pump running) for these guys to get
a foothold, so I'm not optimistic. Does that mean I'll soon see a
degradation in my cooling water output even with a clear filter media???
What is the published flow rate of the pump? What is the measured flow rate and entering/leaving temperatures of the condenser water? This is the heat transfer method and increased condensor water flow can improve efficiencies.
I have no idea, at this point, whether the Carel thermostat I took out (his
electronic control has a Carel incorporated) was accurate, but I'd had it
set at 8° with a 2-degree hysteresis; it maintained it easily. This box
shows temps radically above that - the probe is near where the other was -
but shooting it with an infrared thermometer shows it to actually be about
10° at the spillover near the fan, and other temps much lower. E.g., bread
closest to the spillover 5°, hamburger package top near the plate 0°,
chicken package vertical to the plate -3°, and so on, with all three plates
well under 0°. So, regardless of the calibration, including that I've now
upped the plate shutoff to 6°, it's pretty cold in there, and the reefer
does (a good thing; it's been cold enough in the past to do it solely by
convection) occasionally have to use the spillover fan. I have yet to put
ice cream in there, but I suspect it would be OK. But still, it's an energy
hog.
Do you have a remote sensing device for box temperatures, preferably a certified or calibrated thermistor thermometer with remote leads? Are you sure of the infrared thermometer readings, especially in this temperature range?
If there had been any way short of pulling the boat (for a new keel cooler)
and destroying the galley (to get a new evaporator into the freezer), I
think I would have been much happier with a Frigoboat keel and air cooled
(air for when on shore, per Rob, Frigoboat's distributor in the US)
evaporator system, but also to move more air over the compressor),
protected - by the addition of a filter-dryer - from years-away refrigerant
oil contamination, allowing the capillary tube system to do its work. As it
is, the solution seems to be that I MUST run our Honda genset, every day,
for a full tank, about another ~$150/month, to keep up with the load. It
wouldn't take very long before even ditching and replacing the system every
5 years or so, including the necessary haulout, would be more cost efficient
than what I have now - if it were possible to replace the evaporator without
having to start over in the galley.
Have you measured the actual voltage drop between the circuit breaker and the compressor?
Finally, to forestall questions about the box itself, it's 6" of extruded
polystyrene, encased in epoxy, with radiation and conduction barriers
outside (aluminum foil and doorskin furring strips to give an air gap).
Both doors are double-gasketed, and, after much fiddling, I'm confident that
the gaskets are efficient. The boxes are, respectively - 16.25"D, 24.5"H
and 14.75/28.5"W - 3.4 and 6.56 CF respectively.
Have you used the infrared thermometer to measure the temps outside of the box, just to check the insulation performance? Are there any drains in the bottom of the box? Are the refrigerant line/temperature control wiring penetrations into the box sealed?

This is tough to analyze long distance. I would suggest another examination by a real smart tech experienced with hybrid systems such as yours and I would start from scratch: Assume nothing and question everything. Good luck!

[skipgundlach]

I'm old, and I'm slow, so I'm not sure how to do the colors and quotes umpty times to the very excellent questions.

For starters, before getting into the list, what I have is a Sea Frost TWXPAW - Tradewinds XP Air-Water Cooled System: includes Condensing Unit, Receiver Filter Dryer, Constant Pressure Valve kit, and Electronic Thermostat Thermometer with Speed Control - which had 3 evaporator plates in series as the cold part.

This was designed in a collaboration between my installer (after conclusively failing out the previous Frigoboat system) and the manufacturer. The plates were originally to be 2x 15x19 but that was too big - he forgot to allow for taper at the bottom. They became 3 smaller plates, approximating the surface area of my previous evaporator, bent before the lid/countertop went on, and thus fitting easily. My door opening precluded going back that way with any confidence of success, leading to the above solution.

Now, to try to answer the questions as posed:

Some suggestions:

Having retired from a mechanical engineering career, I would approach this as I would any refrigeration project, and would first start with a load calc. What is the calculated load? And the answer is :

Q = U x A x Delta T, or load equals (transmission of heat through your insulation or assembly ) x (surface area of the insulation/assembly) x (cooling load temperature difference or delta T).

You should have some idea of the anticipated load in order to assemble the proper components of the system and to evaluate the performance once installed. This is not something that should be guessed at or assumed due to "rule of thumb" estimations.

Cleave offered to do a BTU calculation for me, but we didn't do so, as it was the same setup as we'd had in our Frigoboat, which worked very well. However, it might be useful; the sizes and specs (amount of insulation) were shown previously.

[/I]This is the first area of concern, as series evaporators can be challenging. Wasn't a single evaporator available/possible? Was this the recommendation of the supplier, Seafrost?

No, for the above reasons: I assume it was a collaboration between my installer and Sea Frost. And, I was mistaken, apparently; its core is a BD80 (brain fart/CRS).

It's unclear how this heat rejection is arranged. Is it user selectable for either air or water cooling? How is this piped?

This system is either air alone, or added water, controlled by a switch on the box. It's piped through a TH which was previously for AC and has a dome filter on it, thence to the ~1A, 3/8" discharge pump and onward to the "box" and out the previous AC water outlet, until now, unused.

[/I]I am unclear what you are referring to by hysteresis.

The gap between shutoff and restart in degrees; mine is F but selectable also for C.

[/I]Unclear. Are you saying that overnight energy consumption is 8A at 80% runtime per hour (6.4 ah)?

Very reliably, whatever my Trimetric says is my AH deficit when we turn off the lights, however many hours later, when we get up, it's nearly exactly 8x the number of hours added AH deficit.

A couple of days ago, just for curiosity, I put it on "low" (slowest speed, regardless of temps). For 36 hours (two nights and one day) I never saw it cycle. I.e., it ran continuously - and the freezer temps continued to inch higher.

When I returned it to "automatic" - a complicated algorithm which adjusts in 400RPM increments, trying for a 52% run time (never happened, yet, in my recordings; the best is about 60/40, but mostly 2/3 or higher), the consumption remained the same but it became more efficient (I guess - it cycled, and continues to do so as I write).

I'm making an assumption that my TM2020 is at least nominally accurate, as, based on the numbers seen during charging (positive amps), the time to recharge to the indicated AH deficit is consistent with what I see.

So, however it's done, with nothing other than the refrigeration, some panel overhead (indicator lights), and a couple of 0.1A fans running, reliably I average 8AH use for each dark hour. When the wind is blowing (a rarity, currently), that may come down a bit, and, if we're off the boat, everything turned off, the sun shining and the wind blowing, we can cut that average use down to perhaps 3 constant/average amps (gone from the boat 8 hours, have a 25AH deficit, e.g.).

[/I]Do you have any empirical data on the suction side (return line)/liquid side (supply line) temps?

Ambient temp 79, return line @ plate joint 39, plate next to it -8, bulkhead (line inside 7+", then another 15 to last plate) exit of return line 72, exit air 88, exit water (both taken at compressor/condensor box) 88, filter-drier 88, all per same infrared shooter.

[/I]Unclear. Are you saying that overnight energy consumption is 8A at 80% runtime per hour (6.4 ah)?

It seems that regardless of cycling or constant (low speed) running, we use 8A average; e.g. 80AH deficit in 10 hours.

[/I]As an aside, freezer temps are not sufficient at 20 degrees F for extended food storage. Required temps vary with the type of product stored, but for safety should be closer to 0 degrees F.

That was my feeling exactly. However, a true box temp of zero F would cause freezing in my reefer; where we have it now (actual ~8-12 other than against plates, despite the probe readings of cycling between about 11 and 20F) allows the reefer to mostly remain in its narrow range (32-34; COLD coke and beer!) without the fan running. When it DOES - like if warm loaded, or even the door opened for a bit, sometimes - it comes down very quickly, with the expected associated quick rise in freezer box temp.

I'm OK with that, other than the apparent energy needed to achieve that.

[/I]What is the published flow rate of the pump? What is the measured flow rate and entering/leaving temperatures of the condenser water? This is the heat transfer method and increased condensor water flow can improve efficiencies.


I have no idea about most of the above, other than the info I presented. I'm sure the water is in the mid to upper 80s next to the hull. Having bathtub water, I'm sure, isn't a great coolant, however, with the same to be said about the air in the ER where this is located (no engine running; just ambient air).

[/I]Do you have a remote sensing device for box temperatures, preferably a certified or calibrated thermistor thermometer with remote leads? Are you sure of the infrared thermometer readings, especially in this temperature range?

Presumably, both the reefer and freezer probes, combined with the Carel thermostats, are reasonably accurate. No, I don't have a calibrated one. However, the temps were so far off the expected on the first go-round that the installer replaced both of the plate and box probes - and, later, the CPV. As to the guns, no two guns I've ever had in the same place and time have agreed, whether fellow cruisers' or the installer's - which, by the way, didn't agree with the mechanical thermometer he bought to see what was "real" in the box; without some presumably very expensive gear, I don't know that we can rely entirely on the many devices we tried in an attempt to get a meaningful reading.

However, the thermostat and probe are the same in the reefer as was the case in the prior system, and the reefer portion is behaving as expected with the indicated temps. That's sort of my gauge for whether I think I'm getting performance equal to what we used to have.

[/I]Have you measured the actual voltage drop between the circuit breaker and the compressor?

No. However, the wiring runs are very short, #8 wire, and a dedicated circuit (not from a panel with common bus).

Have you used the infrared thermometer to measure the temps outside of the box, just to check the insulation performance? Are there any drains in the bottom of the box? Are the refrigerant line/temperature control wiring penetrations into the box sealed?

This is tough to analyze long distance. I would suggest another examination by a real smart tech experienced with hybrid systems such as yours and I would start from scratch: Assume nothing and question everything. Good luck!
[/QUOTE]

As above about the infrared; no holes anywhere that haven't been sealed (dum-dum on the in and outside of the lines and wires hole) or double gasketed (top load freezer, front load reefer) - and, BTW, there are no cold spots on the doors or around the periphery on the counter, panel, or latches/hinges.

At this point I question everything, with the fear that I become a pest to anyone actually able to do something constructive (let alone here in CF, where I'm a fairly well-documented pest).

I'm wondering what makes "hybrid" (don't understand the term in this context). My installer seems to have been a very well qualified guy, having been the ONLY reference for me to see to try to fix my Frigoboat nightmare after literally months of working with the US distributor, but he declared it as fit as it was going to get after more than a month of working on it himself during a road trip we took. That assured the best possible conditions - never opened other than for reference, never warm-loaded, relatively cool (December in St. Augustine) temps, gauges attached and monitored, filter-drier view hole monitored, etc.

I apologize for the cut-and-paste, but hope that its proximity to the original will give context if it's not immediately apparent here.

L8R

Skip

[hellosailor]

Skip, I'm either easily confused or maybe just perennially confused and my computer just told me the internet is broken and ate my reply so I'm going to try again.

You said "It covers my removal of a previously very satisfactory Frigoboat system and replacement with a Sea Frost air and water cooled system..."

but it sounds like the old Frigo installation was only satisfactory until it failed. Which is not satisfactory. And then the recommended technician and the factory folks couldn't get it to work again, so you went to a second brand and second set of folks who couldn't make a SF system work anywhere near as well.

See, I'm confused because it sounds like there's no clear problem with any of the equipment but the problem is that shopkeepers or butchers have taken over the nosiness (as usual) and no one was able to make any refrigeration work well for you.

Because good help is hard to find and custom systems of any kind, don't work so well if you can't find good help to install them and set them up.

Did I get that translated right, or I am just, still, and perennially so easily confused?

[skipgundlach]

Originally Posted by hellosailor

Skip, I'm either easily confused or maybe just perennially confused and my computer just told me the internet is broken and ate my reply so I'm going to try again.

You said "It covers my removal of a previously very satisfactory Frigoboat system and replacement with a Sea Frost air and water cooled system..."

but it sounds like the old Frigo installation was only satisfactory until it failed. Which is not satisfactory. And then the recommended technician and the factory folks couldn't get it to work again, so you went to a second brand and second set of folks who couldn't make a SF system work anywhere near as well.

See, I'm confused because it sounds like there's no clear problem with any of the equipment but the problem is that shopkeepers or butchers have taken over the nosiness (as usual) and no one was able to make any refrigeration work well for you.

Because good help is hard to find and custom systems of any kind, don't work so well if you can't find good help to install them and set them up.

Did I get that translated right, or I am just, still, and perennially so easily confused?

I think your translation was probably pretty good. I also, however, am in the ranks of the easily confused, which is why I check my understanding(s) with others frequently :/

As to the internet, I, too, have occasional instances of a gobble-up. In fact, I thought my reply had done that to me, but it was saved by the left-arrow previous page, which, fortunately, apparently had cached, and it went the second time. I'm not sure what I would have done had it not been able to retrieve it, but I can assure you it would have been noisy

Unless either my consumption with the Frigoboat system was equally as high, and I just didn't notice it (in no-wind/no sun conditions we'd run the Honda about every other day), or there's some magic going on here. I do confess (never having had reason to doubt my prior system), I didn't make the same sort of detailed notes about the behavior of the FB installation. There was a time when I had to replace an o-ring in a quick-connect fitting, but once that was done, and the appropriate level of 134a was added, all was well again.

I have owned cars which fit the same description, though their descent into not-good usually wasn't a matter of a design problem (the cap tube method in the FB system) but simply wearing it out, so I don't object to them dying so much as I did the FB. However, the replacement, which aside from how long it has to run, and at what power demand, to keep stuff the way we used to have it, from all appearances, works just fine.

It's all a matter of what one is used to, probably, but I can't wrap my brain around having the cut-in/cut-out done by measuring the plate, and a separate system for telling you what the temp is in the box. My hysteresis is also WAAY bigger - and on the plate, too, a presumed much-slower reacting medium than the air/stuff in the box - than the FB's too, and that gives me the worries that it can't be good for the stuff in the box. OTOH, cold-platers have that as a FOL, and seem to be "ok" with it, so I presume I should just grin and bear it.

If you've bothered (not that I asked you to) to wander around the early refit pictures in my gallery, you'll see that we took some considerable pains to make this the most efficient box possible; I think we succeeded in that, even though the door gaskets didn't get fully resolved until recently. If it weren't for the fact of vac panels eventually losing their vacuum and needing replacement (~15 years for all of it to be just air, if my fellow researchers were correct), I'd have sandwiched that into my construction as well. The wisdom of the time (Kollmann, rParts, Calder, etc.) was that more than 6" of insulation was a greatly diminished return, so that is what we used. And, despite it being already "waterproof" we encased it in epoxy.

The thought of an average of 1-2A over a full day, which seems to be common, in boxes of similar size, based on comments to this thread, is beyond my comprehension, even with the prior FB. Of course, I expect we keep our reefer much colder than most folks, and expect to pay a premium in amps for the privilege, but 400-800% seems a bit excessive. In return, I constantly hear bragging (in RL, not necessarily here) about zero degree freezers. We've always been a very great height from that, though we DID make the FB do that at one point in its life; it did so without complaint and would have kept right on going down (to some point; we didn't try) if we'd asked it to do so. Because the amps are already very impressive, and, at low speed, we can't even make the box get to temps warmer than previously normal, we've never tried to get a zero degree box. SF's manual states that it's common for the box temps to be quite higher than the plate temp, inferring that you have to ask the plate to get a lot colder than you actually want the box to be satisfied with the result.

So, I continue to be confused about why the sensing probe is at the plate, though (see other thread noted at the start, here) Kollmann, an active participant in the FB saga, likewise, was all about "what is your plate temp" - so apparently that's the industry norm, rather than the box-temp-as-control that FB uses.

As above, I remain easily confused :/

And, without quoting the particular response, saying "a system should use 50-60AH" (or whatever it was Calder supposedly said; I can't see that post from this screen) a day is like saying a car should hold 6 people and go 100 mph at 40 mpg. Unless you have a bus, or a sports car, or any of hundreds of different possibilities, you could have just said "a car (etc. not mentioned) should do that - not everyone has or wants a 6-psgr 100mph/ car, but many would consider 40MPG to be a reasonable goal. That information is useless without parameters. My parameters are (at least I believe so) are well set out in the priors. Curiously, even though I copied him on it, Richard Kollmann has been silent on the matter while having been deeply involved in my FB challenges. It would be interesting to get his perspective on this challenge...

L8R

Skip

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[hellosailor]

I'm guessing that the plate temperature reflects what is happening in the cooling loop itself, as opposed to the box temperature which is going to reflect that, but through the distortion caused by heat transfer into an imperfect or loaded box. If the plate temperature is "right" however that is defined, the system is working properly and then the box temperature will eventually follow along, with the only variable being how much the system has to work to compensate for the heat bleeding through the box.

Refrigeration and varnish work: Two things that must always be mysteries in life.(G)

[Richard Kollmann]

Originally Posted by skipgundlach

I think your translation was probably pretty good. I also, however, am in the ranks of the easily confused, which is why I check my understanding(s) with others frequently :/

As to the internet, I, too, have occasional instances of a gobble-up. In fact, I thought my reply had done that to me, but it was saved by the left-arrow previous page, which, fortunately, apparently had cached, and it went the second time. I'm not sure what I would have done had it not been able to retrieve it, but I can assure you it would have been noisy

Unless either my consumption with the Frigoboat system was equally as high, and I just didn't notice it (in no-wind/no sun conditions we'd run the Honda about every other day), or there's some magic going on here. I do confess (never having had reason to doubt my prior system), I didn't make the same sort of detailed notes about the behavior of the FB installation. There was a time when I had to replace an o-ring in a quick-connect fitting, but once that was done, and the appropriate level of 134a was added, all was well again.

I have owned cars which fit the same description, though their descent into not-good usually wasn't a matter of a design problem (the cap tube method in the FB system) but simply wearing it out, so I don't object to them dying so much as I did the FB. However, the replacement, which aside from how long it has to run, and at what power demand, to keep stuff the way we used to have it, from all appearances, works just fine.

It's all a matter of what one is used to, probably, but I can't wrap my brain around having the cut-in/cut-out done by measuring the plate, and a separate system for telling you what the temp is in the box. My hysteresis is also WAAY bigger - and on the plate, too, a presumed much-slower reacting medium than the air/stuff in the box - than the FB's too, and that gives me the worries that it can't be good for the stuff in the box. OTOH, cold-platers have that as a FOL, and seem to be "ok" with it, so I presume I should just grin and bear it.

If you've bothered (not that I asked you to) to wander around the early refit pictures in my gallery, you'll see that we took some considerable pains to make this the most efficient box possible; I think we succeeded in that, even though the door gaskets didn't get fully resolved until recently. If it weren't for the fact of vac panels eventually losing their vacuum and needing replacement (~15 years for all of it to be just air, if my fellow researchers were correct), I'd have sandwiched that into my construction as well. The wisdom of the time (Kollmann, rParts, Calder, etc.) was that more than 6" of insulation was a greatly diminished return, so that is what we used. And, despite it being already "waterproof" we encased it in epoxy.

The thought of an average of 1-2A over a full day, which seems to be common, in boxes of similar size, based on comments to this thread, is beyond my comprehension, even with the prior FB. Of course, I expect we keep our reefer much colder than most folks, and expect to pay a premium in amps for the privilege, but 400-800% seems a bit excessive. In return, I constantly hear bragging (in RL, not necessarily here) about zero degree freezers. We've always been a very great height from that, though we DID make the FB do that at one point in its life; it did so without complaint and would have kept right on going down (to some point; we didn't try) if we'd asked it to do so. Because the amps are already very impressive, and, at low speed, we can't even make the box get to temps warmer than previously normal, we've never tried to get a zero degree box. SF's manual states that it's common for the box temps to be quite higher than the plate temp, inferring that you have to ask the plate to get a lot colder than you actually want the box to be satisfied with the result.

So, I continue to be confused about why the sensing probe is at the plate, though (see other thread noted at the start, here) Kollmann, an active participant in the FB saga, likewise, was all about "what is your plate temp" - so apparently that's the industry norm, rather than the box-temp-as-control that FB uses.

As above, I remain easily confused :/

And, without quoting the particular response, saying "a system should use 50-60AH" (or whatever it was Calder supposedly said; I can't see that post from this screen) a day is like saying a car should hold 6 people and go 100 mph at 40 mpg. Unless you have a bus, or a sports car, or any of hundreds of different possibilities, you could have just said "a car (etc. not mentioned) should do that - not everyone has or wants a 6-psgr 100mph/ car, but many would consider 40MPG to be a reasonable goal. That information is useless without parameters. My parameters are (at least I believe so) are well set out in the priors. Curiously, even though I copied him on it, Richard Kollmann has been silent on the matter while having been deeply involved in my FB challenges. It would be interesting to get his perspective on this challenge...

L8R

Skip

Morgan 461 #2
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Skip your Refrigeration story is not the worst or longest in the data of my four hard drives but is the best documented. Yes I have followed your adventures in 12 volt refrigeration powered by Danfoss compressors. With the exception of Frigoboat and E Z Kold other manufacturers units even with flaws in design their units are repairable short of total system replacement. This industry is slowly loosing ground by acquisitions or diversifying into other markets than 12 volt refrigeration.

Skip you and I have as well as this forums readers have witness the lack of expertise in small boat refrigeration. Smart local refrigeration personal are no longer interested in getting involved in these unconventional 12 volt refrigeration units because of nonproductive upgrades adding gadgets to a functional design. Boaters complain when they contact a leading manufacturer or his vender for help they report a runaround and their system is out of warrantee. If the manufacturer can not help with refrigerator troubles who can? I do not believe there are five people in the world that understand the individual designed in problems of Danfoss BD compressor systems from Frigoboat, Adler Barbour, E Z Kold or any water cooled Danfoss system.

After working over twenty years with 12 volt refrigeration systems I get requests for help from 3 to 15 boat boaters a week. Other than refrigeration performance questions Frigoboat keel cooler systems and Adler Barbour electrical wiring problems are the most difficult to handle. I have started to post TECH TIPS on my web site For solutions to major troubles with boat refrigeration. I have not posted a Tech Tip on Frigoboat Keel cooler units as my library is so full of comments sorting through them is a project.

Frigoboat warns about operation of keel cooler systems when out of water. There is also concerns about allowing compressor to over heat in warm climates.

If performance of keel cooler system is in question:

Install troubleshooting LED if not provided as it will lead you to trouble area. See My Tech Tip 2 for a understanding of LED Codes Remember a three flash error code on BD compressors is almost never never a Locked Rotor as manufacture or service tech will tell you.
Big mistake if you or someone tampers with refrigerant of or even connects gauges to this system. Unlike capillary tube systems with conventional condensers there is very little room for excess liquid refrigerant to be stores so do not screw with refrigerant volume. If compressor will not run it is not because it needs refrigerant.

Amperage draw of unit is a good indicator of system’s performance and frost on evaporator surface indicates refrigerant flow.

Restricted refrigerant flow is not always a major problem as moisture in refrigerant will cause restricted flow also.


Skip, as to realistic reports of low amp-hrs consumed every figure you hear is not quantified by reliable data and even if it was there are no two boats exactly the same. Would I believe 40 amp-hours for a six cubic ft refrigerator box per day in the tropics probable not because 25% to 50% of amperage is consumed per day is throughput of liquids. My first question is what temperatures are maintained in this six cubic ft box 60 degrees F.