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Old 17-12-2014, 06:07   #46
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Re: Skips new Seafrost poor performance problem

Thanks for all the comments.

Mark's unit seems to be pretty similar to what we have, and I agree with his assessment that our unit is the problem, not our box.

Unless there is something which catastrophically affected our box, between summer and winter last year we went from the ability to keep up with our freezing and spillover-provided cooling regime with under 6A (high on a bd50) on keel cooler only, to not being able to keep up with cooling even with water and air at ~7A (low with water on bd80), regardless of run time, including nonstop. Actually, that's not even sufficient of a rant, as we kept it cold in hot weather with the FB, but couldn't other than at high with water - MUCH higher amps - with the SF.

In the case of the FB, I didn't do the sort of detail of how long it ran as I did with the SF - but I'm sure it didn't run all the time, as the SF would have to do, well above "low", and entirely unsuccessful running at "high" on air only, in the summer.

The failure of our FB system is well covered elsewhere in this forum, so I won't rehash it other than to say that when the blockage was moving, our system would pull the freezer down well below zero F; I have NEVER had a plate temp to zero (at the probe, bottom of the last plate), let alone a box temp of under zero, in the SF.

Thus I conclude that either the system is simply unable to deal with heat removal (which is no worse than our FB system, up on jackstands, in 95° heat, relying on air only to carry the heat off the keel cooler, as we had in our refit of the bottom in Ft. Pierce), or there is some problem which none of the correspondence and testing per instructions from SF's Cleave Horton has uncovered, not insulation or other structural issues.

That we have had to run the Honda literally every day in order to keep up with the amp load (compared to every 2-3 days in, for example, the Bahamas in the summer, with the FB) of the SF was very nearly the end of our boating, as the admiral was entirely fed up with the noise, and almost quit. She may, yet, let alone the added cost of that gallon of marine, alcohol-free, gas a day (only about a 33% premium here in Vero Beach over the garbage on the street).

I am not an engineer, though I think like one without the math, and about the only thing I can imagine would be the 3 SF evaporator plates (SS clad over piping inside, with some sort of spacing but not a eutectic), vs the very thin FB evaporator plate wrapped around the same space, can't cut it. The FB thin plate and the bd50 keel-cooled only was entirely adequate to the job, whereas our system struggles with water and air cooling, and simply can't keep up at full blast on air alone in the summer. That we have 4 boat bux tied up in this replacement, and can't achieve anything remotely similar to our FB is worse than frustrating. To have the manufacturer tell me that their much-larger system than my prior can't handle it, and that I'll need to install another system to handle refrigeration not only is disgusting, but outrageous

YMMV.
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Old 17-12-2014, 06:13   #47
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Re: Skips new Seafrost poor performance problem

Quote:
Originally Posted by skipgundlach View Post
Mark's unit seems to be pretty similar to what we have, and I agree with his assessment that our unit is the problem, not our box.
To be clear, without you actually measuring the quality of your box insulation in some standardized way, I don't have any assessment regarding your problem. Only a suspicion. But you really do need to nail down the insulation value of your box before going any further.

Mark
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Old 17-12-2014, 07:01   #48
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Re: Skips new Seafrost poor performance problem

Hi, again,

I've just been reading to see what I've missed (I've been 'otherwise engaged' so haven't seen this thread for a while), and wanted to comment on Rich's post (very nice, BTW) with quotes.

Quote:
Originally Posted by SV THIRD DAY View Post
There are two possibilities here.
1. Skip has had something horrible happen to his insulation that would make a BD80 compressor incapable of handling the 10CF classic spillover system when a BD50 could.
Or
2. The SeaFrost system is malfunctioning.
I'm wondering, as you're not the only one who's said this, what sort of issue might cause a catastrophic change in R value on our box.

You most likely won't have seen how we built it (in the early parts of our gallery), but if a box can retain it's insulating properties, I'd expect ours would be one of them.

Yet, in my ignorance, I can't believe the SF is malfunctioning.

Classic mexican standoff...

Quote:
Originally Posted by SV THIRD DAY View Post

We do 10CF classic spill over systems literally every week, including test box runs at 70 and 90 deg ambient temps and it works...the data and testimonials don't lie. So it has to be either 1 or 2 above.



Quote:
Originally Posted by SV THIRD DAY View Post
Now here something that is probably hurting you Skip. I've known you for years online and have read almost every post you have made from the beginning, so I love you and your cruising and posting, sharing style. BUT it freaks a lot of people out....especially vendors that don't feel as comfortable as I do with what goes on online. So I'm just saying that some seeming lack of support could be out of fear of having the "dirty laundry" of a troubled unit being shared so openly online. I've spoken to vendors that tell me (and I am NOT saying SeaFrost is one of them) that once a client with a problem takes it online they stop providing support to that client and basically limit communication in a damage control mode. I've heard this from more than one vendor while standing around the boat shows killing time during a slow spell.

Vendors are scared to death of chat rooms, blogs and clients that have a large online following. I get it having had a blog while cruising with 1500 visitors per day (peanuts I know but it did earn me $150-$200/mo in Google ads). But all the marketing consultants alive will tell you, as a business Never to discuss any potential negative issue online...never put anything in writing that you think will hurt you on a blog or chat room. In fact a online marketing company we hired to help improve our organic google search results when people type in the word "water maker" found my personal blog and user profiles on cruising forum and other sites and told me to delete them all immediately! I was told it was all risk with no reward to say things....anything online these days. Well...Mr smart ass me told that guy to F-off and we fired him because I enjoy posting my rants and advice online and am not going to change who I am just so evil google will like me more.

OK...I know I'm drifting off topic, but the folks at SeaFrost could be more worried about your overly detailed postings all over the internet than they are about helping you fix the system....so they clam up rather than trying to help. Just something to consider from a long time follower of your adventures.

Like I said before if you had one of our systems with this horror story...we would send you a new one and get that one back to the shop for testing. I don't care is we lost every cent of profit we made on the original sale...its just how I do business. AND we have had CoolBlue units fail and embarrassing **** go wrong...our poop smells just like everyone elses so I'm not knocking SeaFrost in any way. What matters isn't that a company doesn't ever lay a pile on the lawn...its how they clean it up!

I fully appreciate what you say, Rich.

I went the factory support route long before getting involved here, and got nearly nowhere, mostly in emails (as I do a great deal better with the printed word than trying to remember what someone said, or whether the question(s) I ask get answered in the face of likely miscommunication (I'm known for pissing people off when I have no such intent). The couple of times I spoke with Cleave (vs the infrequent email responses) were not productive; in the instance of dealing with an unfrosted bottom of the third plate, his advice over the phone was to play with the constant pressure valve.

MAYBE that's the source of all this grief - but I've had to twiddle that thing EVERY time we defrost/lay up (which we do every time we're off the boat, as we'd have no battery whatsoever when we returned, despite our 370W solar and KISS wind generators); what is right one time is far off the next, so I have to muck with it until it's right (which is to have the return line frost next to the plate, but no further, I think, and certainly not outside the box).

So, it wasn't until after consultation, such as it is/was with Cleave, and with Richard, for that matter, who was involved in the attempts to get our FB working, that this came out (note the author on the thread)...

As you've seen me elsewhere, you know that when I get good customer service, the world hears about it loudly and often from me. As the particular ones I have don't do refrigeration, I'll save you the bandwidth, but you know what I mean.

If Cleave had said something on the order of what we've seen here, and asked for me to pay for, if I'd done something wrong, a competent tech who he'd recommended, to inspect and adjust our system, I'd have been all over it.

Instead, it was "play around with it" - and no change other than I get, eventually, the frost line to where it should be without all that mucking about.

Quote:
Originally Posted by SV THIRD DAY View Post
Bottom line...you have a problem still with that unit and need a refrigeration expert aboard to figure it out because I doubt your insulation suddenly went bad. Good luck my friend and even as a competitor to SeaFrost I'm rooting for them to figure out the problem and make it right. Randy here at Technautics and Cleave at SeaFrost are two of the old times icons in the marine refrigeration business and have forgotten more about marine refrigeration than most folks will ever know.
☺ As above. I admit to being a tyro at very best about refrigeration; the installer we used was specifically recommended by Rob of FB; I'd even volunteered to bring the boat to HIM; from that, and from watching him, I presume that Clay was competent - but it took him a month of mucking with it while we were away inland, in other than tropical conditions, replacing three components including the pressure regulator, to get the freezer to where it could keep ice cream appropriately (which is far above zero, and which we don't do), and finally giving up and adding water cooling. That doesn't sound like the system we both expected.

So, I'm certainly open to suggestion, but I don't think that we're going to make much difference without a competent, familiar-with-SF, tech coming aboard. With all the expense and grief I've been through, it would have been far cheaper to go on the ground and replace the FB system, even if it required tearing up the galley to get the new plate installed (it MIGHT have been possible to overbend and then straighten the U - that's how I got the old one out, again as seen in the gallery pix). Silly me, I didn't do that.

Off to see if the engine will stay in one piece; every rotating part external to the engine has been replaced since we left the yard after our bottom reconstruction...

L8R

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Old 17-12-2014, 07:26   #49
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Re: Skips new Seafrost poor performance problem

Quote:
Originally Posted by skipgundlach View Post
I'm wondering, as you're not the only one who's said this, what sort of issue might cause a catastrophic change in R value on our box.

You most likely won't have seen how we built it (in the early parts of our gallery), but if a box can retain it's insulating properties, I'd expect ours would be one of them.

………...
So, I'm certainly open to suggestion
What everyone has been suggesting to you is that you do a controlled measurement of your insulation quality. Nobody is second-guessing your box construction, but until you absolutely rule it out, you will just go around in circles trying to get any satisfaction out of SeaFrost or any real help from the experts here.

You need to divide the combination problem up into either a left side or a right side one.

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Old 17-12-2014, 07:34   #50
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Re: Skips new Seafrost poor performance problem

So, I'm uncertain as to how to make this happen aboard.

I take some known quantity of ice at some defined temperature, and put it into a 32° box, and measure, hourly (or some interval), the difference in weight after pouring off the water?

How long does this take, in general, to get an answer?

And, I presume I'll need some reasonably accurate measurement tools, as well?

Not very bright at this, as you can see...
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Old 25-01-2015, 11:24   #51
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Re: Skips new Seafrost poor performance problem

I know I'm a bit thick, but...

Is there a practical way, without being in laboratory conditions, for me to measure that delta T?

Thanks.
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Old 25-01-2015, 13:01   #52
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Re: Skips new Seafrost poor performance problem

Quote:
Originally Posted by skipgundlach View Post
I know I'm a bit thick, but...

Is there a practical way, without being in laboratory conditions, for me to measure that delta T?

Thanks.
The simplest way to test heat loss through insulation is to compare cabin ambient air temperature with exterior surface temperature of insulation. Temperatures inside box should be at normal desired box temperatures in order to get a good test. If the delta T shows less than a 4 degree F. difference insulation is generally considered good to excellent for a boat icebox conversion.
It is always a good idea to test insulation on all six sides of box especially if insulation is open cell or VIPs.

The Ice melt testing without refrigeration provides usable data for a drink cooler and is of no value for a much lower temperature refrigerator freezer.
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Old 25-01-2015, 13:09   #53
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Re: Skips new Seafrost poor performance problem

Excellent.

I can do that.

The engine room forward bulkhead is one part, and the galley the other, of the large sides

I'll shoot the opposing walls (cabinets in galley, bulkhead at aft head), the overhead and the countertop, and, MAYBE, if I empty the cabinet to port, I could get a usable reading for the end of the reefer.

I'll also do separate freezer top-to-overhead; starboard and bottom are inaccessible.

I'm away from the boat at the moment, or I'd do it now. Thanks.

L8R

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Old 07-02-2015, 09:39   #54
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Re: Skips new Seafrost poor performance problem

So, I have just measured the deltas.

1 to 2 degrees F, measured at under 2 feet between surfaces other than the engine room, which was 4 feet.

None higher than 2, but only a couple of 1 degree differences.

Typical 60-61/2, or 57-58, depending on which surfaces.

ER was least different, above freezer door, in the area where we'd cooked breakfast an hour ago, was highest.

4 different measurements on countertop/overhang, from freezer through one place with the sun shining on it for the frig (1 freezer 3 frig measurements).

2 different measurements on the reefer door to under-sink doors.

2 different measurements in the ER, to door into head and to electrical panel door.

What does that tell us?

Thanks.

L8R

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Old 08-02-2015, 11:56   #55
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Re: Skips new Seafrost poor performance problem

I should wait for Richard to weigh in on this, because my method for determining heat leakage is much more accurate than his, but I'll give you a very rough answer to a complex problem.

A rule of thumb for surfaces in still air is 10 watts per square meter per temperature difference in degrees C (the more exact answer depends on the angle of the surface, size of the surface, emissivity, and delta T). Lets say that your surface is on the order dimensions are on the order of half a meter, and your temperature difference is on the order of 1 degree C (1.8 degrees F). If you have 2 or 3 square meters of total surface, you should be losing 20 to 30 watts, or 70 to 100 BTU/hr.

I'm assuming you used an infra-red temperature gun to measure the temperature differences. You should be aware that with infra-red guns the real surface temperature is quite dependent on the emissivity of the surface, and when you are comparing small differences in apparent temperatures your results may be off a lot. For example, the real temperature of both surfaces may be 50 degrees C, the gun will measure 50 degrees on a surface with an emissivity of 1.0, but only 42 degrees on the surface with an emissivity of 0.8.

Ignoring that problem for now, the theoretical answer is-- if your refrigeration system has a capacity of 300 BTU per hour, it should have a duty cycle of 20 to 35% with your box.
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Old 08-02-2015, 12:36   #56
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Re: Skips new Seafrost poor performance problem

Quote:
Originally Posted by donradcliffe View Post
I should wait for Richard to weigh in on this, because my method for determining heat leakage is much more accurate than his, but I'll give you a very rough answer to a complex problem.

A rule of thumb for surfaces in still air is 10 watts per square meter per temperature difference in degrees C (the more exact answer depends on the angle of the surface, size of the surface, emissivity, and delta T). Lets say that your surface is on the order dimensions are on the order of half a meter, and your temperature difference is on the order of 1 degree C (1.8 degrees F). If you have 2 or 3 square meters of total surface, you should be losing 20 to 30 watts, or 70 to 100 BTU/hr.

I'm assuming you used an infra-red temperature gun to measure the temperature differences. You should be aware that with infra-red guns the real surface temperature is quite dependent on the emissivity of the surface, and when you are comparing small differences in apparent temperatures your results may be off a lot. For example, the real temperature of both surfaces may be 50 degrees C, the gun will measure 50 degrees on a surface with an emissivity of 1.0, but only 42 degrees on the surface with an emissivity of 0.8.

Ignoring that problem for now, the theoretical answer is-- if your refrigeration system has a capacity of 300 BTU per hour, it should have a duty cycle of 20 to 35% with your box.
Thanks.

I did, in fact, use an IR gun, but other than in the ER, where contortions would be the rule, I put the gun against the surface in question. In the case of both the ER and the reefer door, both surfaces measured would be the same. The countertop (including the freezer door) is melamine, and my reference surface was painted fiberglass.

I'm a bit constrained to search right now, but I believe I have put up dimensions of our system, freezer and reefer, and the temps we ask them to keep, in the past here.

You can add to that 6" plus bulkhead/panels, all with air and reflective barriers (aluminum foil and doorskin battens); the ER bulkhead is 1.5" painted plywood and the other panels are 3/4" MDA with either teak veneer or melamine. Insulation is extruded polystryene, except for the hull starboard; it's injected 2-part polystyrene, starting at about 5" and working up to more than 13", at whatever width (I forget, now) is between the bulkheads, but a couple of feet or so. Extruded bits (Redboard in our case) were coated with epoxy during installation, with joints stairstepped.

Top is one piece 4" board, the rest is layered 2" and 4" board; the spillover is relatively thin, on purpose, so as to have a wider distribution than just the fan hole. Both compartments have circulating fans which run during system run, and are off if the door opens.

At one point Cleave had worked out what he thought my BTU consumption was, too, I think; his conclusion was that I needed a separate system for the reefer in order to keep up, and, somehow, a total lowered amp draw. I'm not an engineer, but that just doesn't parse, particularly in the face of the BD50 Frigoboat keel-cooled only (no air), until it packed it in, keeping up with aplomb, and, should we have wanted it to, putting our freezer box temperature fully 15-20 degrees lower than we currently are currently keeping it (the reefer has a thermostat on the blower, keeping THAT box - like our freezer used to do - within 2 degrees other than on warm loading), with the HIGH setting using an amp less than the LOW setting on the SeaFrost BD80 with the water pump.

It's only now that both air and water have gotten so much colder that "low" (at an amp more draw than the FB on high) manages something akin to the desired run rate. Because I've been focusing on so much else, I've not done the obsessive time recording such as I did for thousands of readings in this journey over the last two years, but my glancing at the panel in passing suggests it's off more than it runs.

With no other changes in how we use the boat, the northers and highs have allowed enough solar and wind that we run our Honda about every third day, compared to every day in the summer...

Thanks for the attention and informed opinions!

L8R

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Old 08-02-2015, 14:28   #57
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Re: Skips new Seafrost poor performance problem

Skip, if your test was conducted under the following conditions and the average delta T between insulations exterior surface temperatures and refrigerator and freezer interior temperatures showed less than a four degree F Delta T, insulation is good:
  • Refrigeration thermostat has cycled several times maintaining freezer area at 0 to +15 degrees and refrigerator at 34 to 38 degrees F.
  • Temperatures inside boat is at standard day stabilized design temperature of 70 degrees. If insulation heat loss test was done with ambient temperatures above or below standard day conditions add 4% per degree for final averaged Delta T figure. If actual boat interior temperature in tropical weather is 25 degrees warmer than standard day insulation Delta T is doubled.
The ultimate answer you are looking for is; why will a new BD80 compressor system not perform better or even as well as a BD50 compressor system, is this because:
  • System with BD50 a year or two before showed signs of poor performance? This might lead one to believe insulation over several years in live aboard usage allowed insulation to be less effective. Because you followed standard box closed cell insulation procedures and encapsulated insulation in plastic it should not loss any significant R value in the first 15 to 20 years. We know VIP insulation and open cell insulation will out gas and be replaced by moisture in marine refrigeration. There is a major difference in insulation for heating and refrigeration.
  • The next question to answer is the performance of new BD 80 compressor with its 30% more ratted capacity able to lower evaporator temperature to 20 degrees colder than desired box area temperatures.
  • If thermostat is bypassed for 24 hours will freezer area reach -14 degrees below zero? Or is equilibrium between box temperature and system performance reached before box temperature reaches even zero degree temperature.
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Old 09-02-2015, 00:23   #58
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Re: Skips new Seafrost poor performance problem

Quote:
Originally Posted by Richard Kollmann View Post
Skip, if your test was conducted under the following conditions and the average delta T between insulations exterior surface temperatures and refrigerator and freezer interior temperatures showed less than a four degree F Delta T, insulation is good:
  • Refrigeration thermostat has cycled several times maintaining freezer area at 0 to +15 degrees and refrigerator at 34 to 38 degrees F.
  • Reefer and freezer had cycled many times, the measurements being about a week after we recommissioned. Temps are a bit different; reefer is 32-34 (2 degree hysteresis) and freezer - if you count plates AND box temps - was in that area.

    Quote:
    Originally Posted by Richard Kollmann View Post
  • Temperatures inside boat is at standard day stabilized design temperature of 70 degrees. If insulation heat loss test was done with ambient temperatures above or below standard day conditions add 4% per degree for final averaged Delta T figure. If actual boat interior temperature in tropical weather is 25 degrees warmer than standard day insulation Delta T is doubled.
Quote:
Originally Posted by Richard Kollmann View Post
Our interior and exterior temps were on the order of 60 degrees, so somewhat less than your standard day. Given a 1-2 degree delta, 4% would seem to be insignificant (?).

Quote:
Originally Posted by Richard Kollmann View Post
The ultimate answer you are looking for is; why will a new BD80 compressor system not perform better or even as well as a BD50 compressor system, is this because:
  • System with BD50 a year or two before showed signs of poor performance? This might lead one to believe insulation over several years in live aboard usage allowed insulation to be less effective.



  • Not quite. The only deterioration was noted after we left the yard, and the system was ripped out less than a year after that.

    Before that, we'd been entirely happy with the performance, even with the keel cooler in the air, with no water running over it.

    Our freezer, on the same Carel thermostat type as the reefer, maintained 8-10 (same 2 degree hysteresis) unless warmloaded, throughout days which sometimes reached 100 degrees, on a boat without air conditioning other than in the aft cabin.

    I had NO complaints with the system until it started not working at all, then re-booting, so to speak; examinations of prior threads on the subject will reveal that when it DID work, in that period after we relaunched, it could pull the air temps in the freezer well below zero. I have NEVER achieved close to zero temps in the freezer, even on constant high and water cooling (see prior threads in the period where I was monitoring the on-off cycle closely).

    That my installer, recommended by Frigoboat, took a month (in St. Augustine, in December) of mucking around with the air cooling, and eventually abandoning that and adding water cooling seems to me significant.

    Quote:
    Originally Posted by Richard Kollmann View Post
    Because you followed standard box closed cell insulation procedures and encapsulated insulation in plastic it should not loss any significant R value in the first 15 to 20 years. We know VIP insulation and open cell insulation will out gas and be replaced by moisture in marine refrigeration. There is a major difference in insulation for heating and refrigeration.
    Quote:
    Originally Posted by Richard Kollmann View Post
    That's reassuring. It went in during our initial refit; I'd have to go to my gallery to hunt it down, on lousy bandwidth, so I'll rely on my memory to say it was probably 2005/2006 time frame.

    So, it seems I should be in the middle of its life cycle (?).

    Quote:
    Originally Posted by Richard Kollmann View Post
  • The next question to answer is the performance of new BD 80 compressor with its 30% more rated capacity able to lower evaporator temperature to 20 degrees colder than desired box area temperatures.
  • I believe the plate(s - measurement is at the bottom end of the third plate) temperatures can get to under 20 degrees of the desired box temperature. Recall that somewhere along the line, I was able to record plate temps in the minus single digits.

    And, perhaps significantly, our current settings (which allows only outrageous rather than totally unsupportable energy consumption), are for plate temp shutoff at 5.5, with a 6.5 hysteresis. That yields a probe-indicated temp of a low near 10, and a typical turn-on temp (indicated) of very low 20s.

    Ideally, it would be a bit lower, to a lot lower - but then we get back into running the Honda every day, which will (and almost did) drive the admiral off the boat if allowed to continue.

    And, as an aside, even though I know the standard is to measure plate temperatures, my hysteresis is big enough, and the real air temps difference far greater, that it's about like having a cold plate. My box is NOT maintaining anything resembling a stable temperature. How it managed to do so under the Frigoboat design (same Carel thermo as the reefer, with the same 2 degree hysteresis), or that it can't be done in my current setup, is a puzzlement.


    Quote:
    Originally Posted by Richard Kollmann View Post
  • If thermostat is bypassed for 24 hours will freezer area reach -14 degrees below zero? Or is equilibrium between box temperature and system performance reached before box temperature reaches even zero degree temperature.


  • I can't say that I've EVER seen PLATE temps that low, let alone box temps. Granted, I was doing this in hot weather. It may well be that with a non-standard day (under temp) and similarly temperatured water that, if allowed to run full blast air and water cooled, that number would be reached.

    What's the magic bullet WRT that temperature? We do know from non-standard day (plus 20+ air and maybe water) attempts early on that equilibrium was reached WAAAAY before that.

    We also know that the Frigoboat, before it stopped working altogether, would happily pull the box down to mid-single digits negative AIR temperature (probe on the spillover plate as now); recollection had it as -3 to -5 or so, in non-standard (much higher) days.

    So, as we get close to being able to start out again (reassembling the forward bilge pumps after solving some wiring issues and replacing both the 2.5 minute seek electronic one and the 1500GPH workhorse), is it worth doing that test (running it on high, water cooled, with a shutoff of, say, -20 [which I feel very certain we'd never reach]), and see what results? Defrost is less than a week old...


    Thanks.

    L8R

    Skip

    Quote:
    Originally Posted by Richard Kollmann View Post
[QUOTE=Richard Kollmann;1744513]
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Old 09-02-2015, 08:42   #59
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Re: Skips new Seafrost poor performance problem

I've started the test, as today is a Honda day, setting my cutoff to -14. (Note that is the plate, not the box, temp. I have my doubts as to even getting the plate to that temperature...)

We'll see how far it gets in 24 hours...

L8R

Skip
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Old 09-02-2015, 11:24   #60
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Re: Skips new Seafrost poor performance problem

Skip, you may have to live with the 10 cubic ft refrigerated box and the system you have knowing the amp-hrs consumed at 60+ degrees will be increased by 100% in ambient conditions with air and water temperatures of 85 degrees F.

I see only one design difference between BD50 and BD80 compressors you may not have considered as affecting overall performance. Very small systems powered by Danfoss BD compressors are designed to be cycled by thermostats controlling evaporator temperature not box temperature. Controlling evaporator temperature using a hysteresis differential of 10 to 18 degrees F will reduce tendency of compressor to over power evaporator. In an adequately insulated box with evaporator thermostat index number set to produce desired box temperature actual box temperature is held to Plus or Minus of one degree. Because you’re new systems refrigerant flow control is by a fixed low pressure regulator instead of a capillary tube or expansion valve balance between compressor output and evaporator efficiency is important.

The major difference between the BD50 and BD80 is in controlling speed of compressor and how speed change effects performance especially amp-hours consumed. Danfoss BD80 AEO speed controller module increases or decreases systems COP performance bases on thermostat’s controlling action. If compressor does not cycle off in a given running time its speed is increases this means if thermostat is going by box temperature compressor will never operate at its most efficient speed. With Frigoboat’s speed controller the BD50 may not have had enough capacity to overpower evaporator.
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