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Old 01-02-2018, 01:30   #1
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Holding plate freezer 12v recommendations

Hello Forum,

Our Seafrost BDXP freezer has died after a mere 18 months. I have no interest in repairing this unit-it uses 134a, yielding a minimum evaporator plate temp of about 0, meaning that the damned thing basically ran all the time to keep the food at 20 degrees or so. This is not what I'm looking for in a freezer.

So, back to square 1. I want to stick in a higher-capacity holding plate system.

My previous system was a GB unit, and while it drew 45 amps, it would go into 'super cooling' mode while the engine was on, getting the box temp down to about -5f. It wouldn't run all day after that.

So, the EFFECTIVE power use of this system in normal cruising was actually quite low. I want to do this again.

Anybody have a recommendation for a holding plate system that will sort of replicate the kind of operation that the GB had? I would much prefer to have higher loads for short periods than see the thing run most of the day at lower amperage-having the ability to get the box really cold when there's a surplus of power is key.

Thanks.
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Old 01-02-2018, 01:48   #2
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Re: Holding plate freezer 12v recommendations

Hi TJ, what are the interior dimensions of your cabinet, also the wall's insulation thickness and type if possible. Regards refrigerants, R134a is easily capable of providing the evaporator temperatures needed for a freezer with eutectic plates, if applied correctly.

Cheers ozepete Ozefridge | 12 Volt Refrigeration Systems
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Old 01-02-2018, 01:57   #3
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Re: Holding plate freezer 12v recommendations

Pete, it's about 6 cubic feet. Insulation is about 6 inches. It's a good setup.

I'm not on board with 134a. I don't think that it gets cold enough.

The GB achieved eutetic solution temps of -30f. This is the kind of number I want to see when the engine's on. I believe that 404a gets much colder, no?
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Old 01-02-2018, 03:08   #4
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Holding plate freezer 12v recommendations

Attached is a pic of what is achievable with R-134a.
Now admittedly in this case itís winter, and the system was running a lot, but I was curious as to just how cold I could get it, and how much Delta I could get between the fridge and freezer side as it a spill overClick image for larger version

Name:	IMG_0284.jpg
Views:	295
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ID:	163209
There are better refrigerants than 134, but 134 works for our needs
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Old 01-02-2018, 03:13   #5
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Re: Holding plate freezer 12v recommendations

Good insulation thickness TJ. I have 'guesstimated' your cabinet dimensions to relate to 6 CF (165 litre) and fed this into out 'Heat load & Duty cycle estimator' and the heat load is approx 31.3 watts / hr at 40C ambient. (Email me if you want a complete readout for your cabinet) This indicates that your existing system and or cabinet may have a problem as obtaining good freezer temperatures should be easily achieved. You have quoted that the evaporator plate(s) reach 0F (-18C) yet the cabinet was only down to +20F (or -6C) This large difference indicates that there is either (A) insufficient total evaporator surface area or (B) a breakdown of the cabinet insulation.
Questions: (Best to explore these issues before replacing a system that may not be the issue)
(A) What is the total surface area of the eutectic plates as exposed to the refrigerated area? If only one plate on one side then that is a big part of your problem. A freezer must have at least plates on opposing sides of the cabinet and best set off the wall by a minimum 15mm.
(B) If the system has adequate evaporator surface area yet there remains this large difference between evaporator and cabinet temperatures, the cabinet insulation may be the problem. Cabinets constructed without proper inner and outer lining vapour sealing, are prone to saturation and thus destruction of the insulation. This is more profound in freezer cabinets. Look for sweating or cold patches on the cabinet's outer walls as tell tale signs of insulation failure.
Regards refrigerants, R134a is by far the most common and quite capable of meeting your needs. Changing to R404a as an alternative is wrought with problems. It's a bit more complicated that simply changing refrigerants, firstly the equipment, oils and engineering has to be suited to the refrigerant used.
Cheers ozepete
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Old 01-02-2018, 03:28   #6
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Re: Holding plate freezer 12v recommendations

Pete, the numbers are somewhat misleading, one is shooting an IR thermometer onto the coldest part of the plate, the other is from a temp probe at the warmest part of the box. The differential is not that great if measuring like for like.

Remember that the Glacier Bay system performed spectacularly well. It unfortunately died of old age, and we wound up with the SeaFrost in summer '16. The plates are installed as you describe. 2 plates on opposite sides of the box, stood off. I'm not on the boat to measure, but they basically cover both of the bigger walls of the box.

On a very humid, hot day, if there is about a 120 degree difference between the temp of the hull and the reefer box, I can see a bit of condensation on the hull where the freezer is. It's possible that the insulation could be better, but as I said, the GB setup was entirely satisfactory.

EDIT: I really don't think that my problem is insulation related-we were living on board in the UK last winter, and even with frost on the deck, temps near freezing, the coldest the box got (remember, the upper part-warmest part, we don't use a fan) was still around 20 degrees. Bottom line-the ice cream was still soft even when it was freezing outside!

Regarding going to 404a, it is my intent to purchase an entirely new system, not retrofit what I have. I see no difficulties.

The point of going to 404, to my mind, is that it simply achieves colder temps. I'm planning to install a high-load, high capacity compressor, and the lion's share of cooling will be done with the engine running.

I would be happy to be corrected if I have this wrong.

This is how we operated the GB-it was great. Far superior to watching the SeaFrost sitting there sucking 7 amps most of the day.

Pete, if you're offering, or can produce, the kind of system I'm describing, I'd be interested in talking more to you.

Shipping is to Gibraltar.

TJ
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Old 01-02-2018, 03:30   #7
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Re: Holding plate freezer 12v recommendations

Quote:
Originally Posted by a64pilot View Post
Attached is a pic of what is achievable with R-134a.
Now admittedly in this case itís winter, and the system was running a lot, but I was curious as to just how cold I could get it, and how much Delta I could get between the fridge and freezer side as it a spill overAttachment 163209
There are better refrigerants than 134, but 134 works for our needs
This is really interesting. I have never seen a plate temp of below -5F on the IR probe, regardless of how long it runs. I wonder what's up?
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Old 01-02-2018, 05:07   #8
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Re: Holding plate freezer 12v recommendations

Hhmm.. I'm following as I'm really interested in the outcome of this one..

We have a 15 year old "Cold Machine" cooling system installed on our boat. I'm %90 sure its using 134A. Its a BD50 compressor and VD16 evaporator. Just recently it froze an entire Turkey and Christmas Ham down here in the Caribbean (Martinique).

Based on my experience with our system, I think the OP may have something else wrong. I'm interested to see what the experts discover.
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Old 01-02-2018, 05:17   #9
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Re: Holding plate freezer 12v recommendations

Quote:
Originally Posted by TJ D View Post
This is really interesting. I have never seen a plate temp of below -5F on the IR probe, regardless of how long it runs. I wonder what's up?


I donít know, cause my IR thermometer wonít read cold very well at all, itís reads high. First I believe to be accurate you need a flat black body for the emissivity to be correct, and then maybe at very low temps there just isnít much heat to measure, these things are really meant to measure cooking and engine running levels of temperature, not very cold temps.
However I have a calibrated Fluke multimeter with a thermocouple probe that I have used to verify the accuracy of the Accurite.
Now to be completely fair, the Accurites transmitter probe was directly underneath the cold plate in this photo, so the temp is actually closer to cold plate temp than average box temp.
However normally box temp runs in the low single digits, just about the point that ice cream is hard.
Ice cream is I believe the acid test for a Boat freezer.
Now my Engle at it lowest setting seems to run a box temp of -5.

All temps are in Fahrenheit
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Old 01-02-2018, 05:23   #10
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Re: Holding plate freezer 12v recommendations

I have a technautics cool blue on our boat with spillover fridge/freezer and I have gotten temps down to 0 when it is turned up. Most of the time for casual cruising I keep freezer around 15-20. Itís got a pretty big holding plate. Of course it runs a lot more in the summer but thatís also due to the box no doubt
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Old 01-02-2018, 05:25   #11
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Re: Holding plate freezer 12v recommendations

Quote:
Originally Posted by travellerw View Post
Hhmm.. I'm following as I'm really interested in the outcome of this one..

We have a 15 year old "Cold Machine" cooling system installed on our boat. I'm %90 sure its using 134A. Its a BD50 compressor and VD16 evaporator. Just recently it froze an entire Turkey and Christmas Ham down here in the Caribbean (Martinique).

Based on my experience with our system, I think the OP may have something else wrong. I'm interested to see what the experts discover.
So, some more background is in order.

When we installed the system, I let it run nonstop overnight, and was pretty dismayed to find that the temperature in the box was still quite high, about 19 degrees at the top of the box, no fan.

I also assumed that there was something wrong. I called back the company which installed the system. He came down, and we took some IR temp readings. IIRC, we were at -4F at the plate, after running for 16 hours or so.

A call to SeaFrost followed, and they confirmed that this was the correct number for 134a, and that it wouldn't get any colder than that. I expressed a bit of dismay, as my previous system went to -30F at the plates easily.

The reply that I got was that the FDA considers food below 29 degrees as adequately frozen for long term storage, and that their freezers use this as their guideline, and that I would never be able to get the box down to the temp that I wanted-I should have bought a 404 system if I wanted my freezer that cold. It sucks to find this out the day after you install a system.

So, having just spent $3500 bucks on this system, and a transatlantic pending, I resigned myself to it. Ok, I couldn't have ice cream any more (fine for the waistline anyway), but it was a freezer, sort of.

Once we got sailing, however, my dismay increased.

Whereas before, I would run the engine for an hour, and the GB would drive the box temp down to below zero F in a short time, this thing just ran and ran and ran. My effective power use went WAY up, because there was not the option to take advantage of power generating times to get the majority of cooling done.

With the GB, if we motored for several hours, I would see the box temp down at 7-8 below. The thing wouldn't turn on for a day after that.

Anyway, I guess in the end, it's my own fault for not doing enough homework. I was away when the GB died, so I sort of turfed the whole thing off to a contractor. If somebody had told me that the system worked the way that this one does ahead of time, I would have chosen differently.

No matter now, however.

The system broke, and I'm not going to fix it. I'll consider the $3500 as tuition and replace it with a holding plate system that will operate the way I want it to.

Hopefully, someone here has a lead on a good Glacier Bay replacement. That system was awesome.
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Old 01-02-2018, 05:29   #12
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Re: Holding plate freezer 12v recommendations

Hi TJ D

Your problem may not have anything to do with the refrigerant in the system . Our systems are set to run at zero degrees Fahrenheit and have no problem achieving that.
SeaFrost use a constant pressure valve (CPV) to control refrigerant flow , different then a TXV . Yours may be out of adjustment or adjusted wrong for your target evaporator temperatures. These valves do have there shortcomings , efficiency being one of them, but they are simple and reliable .

Contact Cleave over at SeaFrost and Im sure he can guide you though the check list of setting up his system .

https://www.seafrost.com/pdfs/SHORE%...HE%20VALVE.pdf

Sea Frost

148 Old Concord Turnpike Barrington NH 03825 Tel: (603)868-5720 Fax: (603) 868-1040
Sales@seafrost.com

Regards John.
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Old 01-02-2018, 05:30   #13
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Re: Holding plate freezer 12v recommendations

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Originally Posted by a64pilot View Post
I donít know, cause my IR thermometer wonít read cold very well at all, itís reads high. First I believe to be accurate you need a flat black body for the emissivity to be correct, and then maybe at very low temps there just isnít much heat to measure, these things are really meant to measure cooking and engine running levels of temperature, not very cold temps.
However I have a calibrated Fluke multimeter with a thermocouple probe that I have used to verify the accuracy of the Accurite.
Now to be completely fair, the Accurites transmitter probe was directly underneath the cold plate in this photo, so the temp is actually closer to cold plate temp than average box temp.
However normally box temp runs in the low single digits, just about the point that ice cream is hard.
Ice cream is I believe the acid test for a Boat freezer.
Now my Engle at it lowest setting seems to run a box temp of -5.

All temps are in Fahrenheit
I'm not that confident in my readings, really, but the ice cream thing is indeed an excellent benchmark.

Even with the compressor running 24 hours a day, the ice cream isn't up to snuff...

But, anyway, the thing is broken and gone! The topic for me is which holding plate system is the best.
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Old 01-02-2018, 05:33   #14
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Re: Holding plate freezer 12v recommendations

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Originally Posted by malbert73 View Post
I have a technautics cool blue on our boat with spillover fridge/freezer and I have gotten temps down to 0 when it is turned up. Most of the time for casual cruising I keep freezer around 15-20. Itís got a pretty big holding plate. Of course it runs a lot more in the summer but thatís also due to the box no doubt
I tend to try to keep the freezer at around 10 (the ideal temp for Ben&Jerrys, it turns out.
But, the feature that I really want most is the ability to get the temperature down to below zero, quickly, when there is excess power. It will go all day without running again after we shut down.
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Old 01-02-2018, 05:37   #15
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Re: Holding plate freezer 12v recommendations

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Originally Posted by ColdEh Marine View Post
Hi TJ D

Your problem may not have anything to do with the refrigerant in the system . Our systems are set to run at zero degrees Fahrenheit and have no problem achieving that.
SeaFrost use a constant pressure valve (CPV) to control refrigerant flow , different then a TXV . Yours may be out of adjustment or adjusted wrong for your target evaporator temperatures. These valves do have there shortcomings , efficiency being one of them, but they are simple and reliable .

Contact Cleave over at SeaFrost and Im sure he can guide you though the check list of setting up his system .

https://www.seafrost.com/pdfs/SHORE%...HE%20VALVE.pdf

Sea Frost

148 Old Concord Turnpike Barrington NH 03825 Tel: (603)868-5720 Fax: (603) 868-1040
Sales@seafrost.com

Regards John.
Thanks, John. I've always been impressed with Cleave. I've talked to him quite a bit about this already. Good man, that one.

Maybe it's worth replacing the module (troubleshooting indicates that the module has failed) and having another crack at it before I chuck it in the dumpster.
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