The Worst pleasure boat refrigeration.

[slug]

Keel cooled temps can run hot when the boat is stationary in warm water
This would reduce energy efficiency

With air cooled it’s difficult to get rid of the hot air in some installations

Many times this means adding an addition fan to ventilate the space

More energy

[robert sailor]

Originally Posted by slug

Keel cooled temps can run hot when the boat is stationary in warm water
This would reduce energy efficiency

With air cooled it’s difficult to get rid of the hot air in some installations

Many times this means adding an addition fan to ventilate the space

More energy

That's true and I experienced that exact thing. The return line to the compressor was unbelievably hot so the unit ran longer with thru hull water cooling...that was the real primary reason I changed over, that and the continuous cleaning of the special thru hull.

The fresh air system was easy to deal with, I did add a computer fan to help remove air out of a large grilled area that housed the compressor. It only ran when the compressor ran and the energy draw was next to nothing. It's just a much simpler system and is nearly bullet proof.

[Richard Kollmann]

RaymonR Quote:
There were a couple of threads on the forum a couple of years age in which Richard and Ozepete battled out the pro and cons of the various systems.

It is true I had a company that manufactured ice box conversion refrigeration systems for boats. We manufactured custom and conventional eutectic evaporator plates for thirty years along with several other companies. The purpose of eutectic plates was to store surplus energy available from large refrigeration compressors. The mistake was made that we believe eutectic holdover energy could also be of benefit to boaters with small 12 volt refrigeration compressors. Unfortunately there are more cons to pro wisdom with eutectic plates unless boat is equipped with alternative surplus electrical power. Of the six to eight companies in US marketing small 12/24 volt compressor eutectic plate systems I think there are only one or two left and they are selling them as cycling plates the same as the much more practical conventional cycling evaporators.

[Q Xopa]

Originally Posted by RaymondR

There were a couple of threads on the forum a couple of years age in which Richard Coleman and Ozepete battled out the pro and cons of the various systems.

Ozepete manufactures systems which have both air and water cooled condensors incorporated in the one package and recommends using hold over, or as they are also called eutectic tanks, to time shift the electricity consumption to the daylight hours.

In actual side by side tests Pete demonstrated that electricity consumption was not only moved to when plenty of solar power was available, it was actually about halved by using the eutectic system because the compressor was not cycling on and off. The economic benefit of Pete's system was the big reduction in battery discharge cycling and the extended life thereof.

In contrast Richard appeared to favor the constant cycling evaporator plate solution and the battle raged for weeks. However, for us lay folks it imparted an enormous quantity of valuable information and if you are trying to build yourself a knowledge base is well worth the read. Pete manufactures systems as "Ozefridge" and Richard installs and services boat refrigeration and they are both very knowledgeable on the subject.

Hmm, I remember that discussion a little different. I'm pretty sure the both sell and advocate hold over plate systems.
Pete has as you point out a water cool option, and Richard uses TX valves was the main differences I recall.

I could be wrong.

[RaymondR]

Originally Posted by Q Xopa

Hmm, I remember that discussion a little different. I'm pretty sure the both sell and advocate hold over plate systems.
Pete has as you point out a water cool option, and Richard uses TX valves was the main differences I recall.

I could be wrong.

Ahh Q Xopa,

By the time they got finished trying to out-argue each other those of us that read every post had gained so much both general and aspect-specific information on boat refrigeration systems someone should have awarded us doctorates in the discipline.

It was one of the most informative threads I've seen on the forum. I'm hoping they are both out there researching and experimenting and that we can get them both cranked back up on the subject sometime in the future.

[Scaramanga F25]

If you have a box problem, I had great luck with Engel for over 10 years. Low power and all in one efficient unit. Still worked well when I sold the boat. My buddy removed his boxes and had 2 in the same spot. A larger fridge and a smaller freezer. Happy.

[Dockhead]

Originally Posted by Richard Kollmann

. . . The purpose of eutectic plates was to store surplus energy available from large refrigeration compressors. The mistake was made that we believe eutectic holdover energy could also be of benefit to boaters with small 12 volt refrigeration compressors. Unfortunately there are more cons to pro wisdom with eutectic plates unless boat is equipped with alternative surplus electrical power. . . .

Sounds like a good idea to me. All the cruising boats I know have abundant surplus power when running a main engine or generator or on a sunny day with lots of solar. And then a deficit of power when "coasting" on battery power. Running a bigger compressor just during those times when there is abundant power and then saving power at other times seems like a very good approach to me.


I used a system with a big engine-driven compressor, run off the main engine, which froze a big freeze plate, and it was great. It would freeze the plate in half an hour and the box was cold for 24 hours. That was in quite warm weather in the Med. I would totally do that again. Why don't we see that system any more?

[Q Xopa]

Originally Posted by Dockhead

Sounds like a good idea to me. All the cruising boats I know have abundant surplus power when running a main engine or generator or on a sunny day with lots of solar. And then a deficit of power when "coasting" on battery power. Running a bigger compressor just during those times when there is abundant power and then saving power at other times seems like a very good approach to me.


I used a system with a big engine-driven compressor, run off the main engine, which froze a big freeze plate, and it was great. It would freeze the plate in half an hour and the box was cold for 24 hours. That was in quite warm weather in the Med. I would totally do that again. Why don't we see that system any more?

My guess at answering this.

Engine pulley and belt driven compressors are not as quick and easy to fit as electric connections.

No belts to change, tension etc.

Easier to find an appropriate space to fit compressor and run hoses.

Not that I'm saying that is universally true but that is the common perception.

Perhaps, also as other threads are discussing, limitations on engine from pulley drives?

Holding plates, I agree. I like em. I just don't think they are as popular because it's not the way most other refrigeration is done.

[Pete7]

Originally Posted by Dockhead

I used a system with a big engine-driven compressor, run off the main engine, which froze a big freeze plate, and it was great. It would freeze the plate in half an hour and the box was cold for 24 hours. That was in quite warm weather in the Med. I would totally do that again. Why don't we see that system any more?

Perhaps easier to fit a second alternator and another battery. Actually a very good situation for a single LFP battery.

Pete

[Scaramanga F25]

On my last 40+ footer cruising boat, I had 2 independent systems. Two eutectic holding tanks in the same super-insulated box. One 12 volt, one engine driven. The automotive a/c engine-driven compressor was very much superior in performance here in Florida and the Bahamas. Short main engine run of 40 mins would charge fridge/freezer and a 150 amp alternator took care of all other electrical needs. Simple systems $1 a day. Air conditioning, if desired in no wind marinas was shore power-driven.
On my little 25 footer I use and "Engle" fridge/freezer which I recommend.

[Dockhead]

Originally Posted by Pete7

Perhaps easier to fit a second alternator and another battery. Actually a very good situation for a single LFP battery.

Pete

Yes, maybe. It's a systems optimization question and the answer might not be the same for every boat.


The boat I experienced this on had very simple electrical systems and so minimal power budget since there was no electrical refrigeration. No electrical refrigeration allowed considerable simplification of the electrical system which no doubt was worth it. On other boats, maybe not, but considering running the reefers may be HALF the power budget on many boats, especially now that we do lighting with LEDs, removing refrigeration from this equation may have very beneficial effects -- like doubling battery run time.


So I doubt adding one battery would equal the benefit from this.


With a biggish LiFePo setup however you will care less about using battery power, so that's a different equation.


And there's something to be said for having BOTH, especially for a boat used for very remote cruising. Redundancy in refrigeration is a good thing. You gain great flexibility in operation. Downside of course is double the equipment, weight, cost.


Or do it electrically, but with a honking big compressor and freeze plate -- and run it only when you've got the main engine or genny running.

[FAST FRED]

Box insulation is the key to low power consumption , although the eutetic systems driven by an auto air cond compressor is insanely powerful, but suffers from requiring longer run times than is really needed.

Mike Adler (ABYS) figured out the problem . The large engine driven compressor is restricted by ice forming on the tubing inside the eutetic solution.With a 1/2 or 1 inch of ice on the tubing , heat exchange is greatly slowed.Ice is an insulator.

In our boat after 3days of sitting, we would switch on the compressor and loose a couple of hundred RPM,, 35HP MD3B Volvo , only to gain the RPM back after 15 min or so.

That is the point the internal cooling lines froze too much to do a rapid job.

Mikes solution was to have a custom made plate where the freon passage was pressed into a sheet of copper , instead of using copper tubing in the plate. This was expensive , especially considering a number of different sized eutetic plates are required for different boats.

I do not think he patented the idea, so if anyone can figure how to create the internal plate style tubing manufacture it would be a grand business.

Perhaps very thin copper could be formed over tubing and glued or soldered in place?

Good luck folks.

[Richard Kollmann]

Quote: FAST FRED is correct about frost build up insulates evaporator coil inside eutectic plates. This is one reason why the are not as efficient as standard evaporators.

What is normally misunderstood about freezing the solution in a eutectic plate with a small 12 volt compressor it takes many running hours to freeze a normal size eutectic plate solid and this power always comes from a battery bank charge. Eutectic plates do not create energy as most waste energy during the phase change to ice. An engine driven or large electric ¾ HP compressor can freeze in 1/20 the time it takes a small 12/24 volt compressor to freeze the same plate. Do the math a four cubic foot refrigerator box with insulation R value of 20 used to support two people’s needs could consume 600 Btu per cubic foot per day. If this were a freezer then use 1200 Btu per cubic foot of box. These figures are worst case hot weather below Latitude 20N or 20S. Above those Latitudes Btu estimates can be cut in half. A BD50 with a zero degree F eutectic solution at phase change temperature will produce at best 300 Btu per hour, a BD80 500 Btu and a BD90 off brand compressor slightly more Btu than a BD80. You can check compressor manufacturers spec sheet output Btu matching the preset freeze point of your eutectic fluid to calculate the 12 volt compressor’s run time the first time to freeze plates.

For true holdover plates they would be designed for a twelve to twenty four hour temperature holding time ½ gallon of solution for refrigerator plate for each cu ft of box. Freezer plates one gallon per cu ft of box. Most of today’s eutectic plates used with small compressors can no longer be called holdover plates as they are really used as cycling plates much the same as other types of evaporators. As long as eutectic plate remains at a low temperature it does have an advantage known as the flywheel affect when warm product is put in box its biggest disadvantage is its space wasting size in many pleasure boat’s small boxes.

[RaymondR]

The eutectic tank V plate evaporator battle was precipitated by Ozepete publishing statistics observed from a side by side series of tests on the power consumption of both systems over an extended period of time.

The source of the electrical power in both cases provided power of the same characteristics to both test beds and the box sizes and insulation were exactly the same. The comparison was valid.

A surprising outcome was that the eutectic system consumed almost half the electrical power of the plate evaporators over the extent of the test period. This was attributed to the vastly reduced number of energy wasting compressor starts and stops by the eutectic tank system, only about one per day versus a number per hour for the plate evaporator system. That is that, even exploiting the limited refrigeration capabilities of small 12 or 24 volt DC compressors, the eutectic system is superior in power consumption terms.

Many of us have installed large battery banks to ensure the provision of electrical power without having to run internal combustion powered gensets. We also install solar panel banks to recharge these batteries. The batteries are a high cost item and have a limited life which depends largely upon the frequency and extent of discharges.

A primary discharging electrical load is the refrigeration system. The use of a eutectic tank in our refrigerators allows us to limit the depth of overnight discharge by exploiting the ready availability of electrical power from solar panels during the daylight hours. Since by significantly mitigating the extent of the charge/discharge cycles we significantly extend the life of our expensive batteries this is a very desirable outcome for many of us.

[Richard Kollmann]

Originally Posted by RaymondR

The eutectic tank V plate evaporator battle was precipitated by Ozepete publishing statistics observed from a side by side series of tests on the power consumption of both systems over an extended period of time.

The source of the electrical power in both cases provided power of the same characteristics to both test beds and the box sizes and insulation were exactly the same. The comparison was valid.

A surprising outcome was that the eutectic system consumed almost half the electrical power of the plate evaporators over the extent of the test period. This was attributed to the vastly reduced number of energy wasting compressor starts and stops by the eutectic tank system, only about one per day versus a number per hour for the plate evaporator system. That is that, even exploiting the limited refrigeration capabilities of small 12 or 24 volt DC compressors, the eutectic system is superior in power consumption terms.

Many of us have installed large battery banks to ensure the provision of electrical power without having to run internal combustion powered gensets. We also install solar panel banks to recharge these batteries. The batteries are a high cost item and have a limited life which depends largely upon the frequency and extent of discharges.

A primary discharging electrical load is the refrigeration system. The use of a eutectic tank in our refrigerators allows us to limit the depth of overnight discharge by exploiting the ready availability of electrical power from solar panels during the daylight hours. Since by significantly mitigating the extent of the charge/discharge cycles we significantly extend the life of our expensive batteries this is a very desirable outcome for many of us.

If you are happy with your eutectic plate system and electrical power upgrade that is all that matters. And yes I have studied and replied to the charts you mentioned. Performance success is in powering eutectic plates with a small 12/24 volt compressor is having a source of alternative power from wind, solar or a water propeller alternator. Without sufficient alternative electrical power or major increased battery capacity engine alternator needs to be operating too many hours per day. Anyone who believes eutectic plates create energy is wrong.

Hopefully we can hear from experienced boaters with eutectic plates frozen from small 12 volt compressors I sold many of them.