Dependable, energy efficient low to no maintenance refrigeration.

[Richard Kollmann]

Looking for the best ice box conversion refrigeration system is confusing especially if you are looking at posted internet forum threads. Adler Barbour, Nova Cool, Electrical Iceman, and a few others set the early standards for the most popular small dependable basic pleasure boat refrigeration systems using the Danfoss BD twelve volt fixed speed compressors. In the early days of small 12 volt compressors few boat iceboxes were insulated well enough and boat electrical power was inadequate for refrigeration. Electric Iceman in Miami one of these standard basic units manufacturers had the most interest sales option, for $25 more added to purchase price you got a life time warrantee.

I get asked to recommend ice box conversion refrigeration systems frequently for boats with four to six cubic foot boxes. There have been major changes to boats and refrigeration system over the last 25 years; Better and bigger batteries, High output alternators, and major changes to volumetric efficiency of Danfoss 12/24 volt compressors. Twenty years ago Adler Barbour’s basic cold machine was the preferred 12 volt ice box conversion refrigeration.

I believe XXXXX complete ice box conversion kits costing under $900 with BD35 compressor will set the new standard for most reliable efficient refrigeration. I do not want to rule any other well designed basic systems but for a system needing a BD 35 compressor XXXXX will be hard to beat.

What is the difference between a $900 to $1050 basic units sold now and $2500 unit sold at the same time? Answer is Creative advertising to convince buyer that unnecessary added hardware will be an improvement in performance and reliability over other competitor’s basic Danfoss BD compressor systems. I have not found factual proof that any of the following comments in most cases are not true enough to justify the cost or performance and lack of reliability involved. Because of the rough marine environment there will be small electrical problems that need to be corrected. Basic simple efficient refrigeration can be maintained most anywhere without a qualified factory trained technician. Adding gadgets to the basic Danfoss refrigeration design is a risk I would avoid.

Sample of strange marketing ideas with unfriendly or unproductive results for systems powered by Danfoss BD compressors:
• Any type of water cooling can compromises dependable reliability.
• Statement, water cooling of condenser is more efficient than air, this is not true if heat transfer in condenser is not controlled.
• Compressor fan cooling is not required as compressor high temperatures are not a problem. Not true in tropical climates or when unit is installed is a small static air compartment.
• BD 35 compressor can maintain refrigerator desired box temperatures 33 to 38 degrees F in box’s larger than six cubic ft. Not true in warm climates.
• Lots of box insulation is the most important part of a refrigeration system. Not true in most cases the onboard energy source is more important than insulation..
• Ice box insulation is not sufficient enough for refrigeration. Not true in many cases.
• Eutectic holding plates are more efficient and more partial than a standard evaporator. Not true unless boat is equipped with alternative energy, solar, wind or connected to over night shore power.
• Holding plates that lack surface area Btu heat transfer equal to refrigeration unit’s Btu capacity.
• Holding plate eutectic solution with incorrect phase change temperature will not produced desired results.
• Cost of a Thermo Expansion Valve and a refrigerant receiver tank can improve a standard evaporator’s performance. Not true if correct standard size evaporators are used.
• Electronic thermostats controls are more reliable and energy efficient than conventional manual thermostats. Not true electronic thermostat are not as reliable in marine applications. As far as energy efficiency in most cases electric thermostats are more likely to unbalance refrigerant flow.
• Sales statement our units are the most reliable, maintenance free and efficient marine refrigeration units. Another case of creative advertising.
• Aluminum evaporators are stamped out by the cargo container in China.
• Your compressor is old best buy my new refrigeration system. Older than thirty years might be compressor retirement age.
• Do you really want to buy one of those low cost basic refrigeration systems?
• Lowering the freezing point of your eutectic solution will allow you to store more energy absorption BTU's than plain water. Incorrect the difference between one Btu in frozen water and one Btu of frozen eutectic solution is almost the same.
• Space age open cell insulation is recommended for marine environments. Only true if tightly sealed to keep out moist air.

[svinshallah]

Just a quick question. How does an electronic vs a mechanical thermostat affect anything? It turns on at one temperature and turns off at a lower temperature. What’s the difference? I could see the reliability argument, although the Carel controller is still working fine after 20 years. Thanks for all the good advice over the years.

[Typhoon]

Mr. Kollman, your insights and observations and engagement in helping others with marine refrigeration has and continues to be outstanding.

Without the careful truth and test based marketing by marine refrigeration manufacturers, the myriad of individuals that are not familiar with your depth of experience may not discover what is important to understand and apply to make good decisions on their needs and purchases.

Marine refrigeration is purchased infrequently, often to replace inoperable or failing systems that originated with the vessel. Buyers make their selection based on energy efficiency, safety and convenience. Some make the purchase decision as a convenience/luxury upgrade from an icebox.

Today it is a critical discussion in overall boat market trends. The market is strong for previously owned vessels, and refit and renovation investment has continued to increase as well-found vessels, particularly fiberglass, age.

The ‘baby-boom’ generation has, or is about to, reach retirement age and so many are healthy, ambitious individuals seeking new sailing lifestyles with long term live-aboard intentions, particularly focused to the tropical travels.

High-quality refrigeration systems add comfort, food safety and not unimportantly re-sell value to a vessel.

While we may not agree on your perspectives of the value of advanced features, we will always agree with leadership in ensuring marine refrigeration needs and options is and continue to be supported for fellow mariners.

At ColdEh we work to have an unfair advantage over system designs and prices and more… It is the fact that we care more and will always help. Just like you.


Regards John.

[a64pilot]

A lot of those statements are very true.
However that is one huge caveat, and that is “if correctly designed” or correctly matched etc.
That isn’t possible in an ice box conversion, it is very, very possible in a complete system like buying fridge that is a complete unit, box and all. There the manufacturer can spec everything to match box size, R value etc to get a perfectly matched system. I say can, but in truth it’s almost never done, what is done is pre existing components are matched potato head style to put together a system, cause that is most cost effective.

However someone who is selling a conversion that cannot control box size, R value etc. cannot match components to the enclosure, the best have more expensive components that allow their system to be more flexible, IE expansion valves and receiver driers, although I believe a receiver drier to be a mandatory piece of kit myself.

My take is that an excess of cooling capacity is desirable, I have never heard of anyone complain that their box temp is just too stable, even right after putting in food, however a system that is at 100% duty cycle and just barely gets by is more energy efficient, but anything trips it over the edge and it can be days recovering, throw in a case of warm beer and see how long it takes for you box to be back at the desired temp., I want it to happen overnight myself.

I would expect maybe to see more and more drop in fridge systems where the whole thing is one component like your house fridge, those everything can be controlled and a happy customer is more likely.

[hellosailor]

"However that is one huge caveat, and that is “if correctly designed” or correctly matched etc."
Spot on. Especially wrt electronic versus bimetal thermostats. Yes, a bimetal strip is do damned simple and rugged it often doesn't know how to die. But a "properly engineered" electronic module, with properly chosen discrete components, a properly conformal coated circuit board, and proper heat sinking and surge supression (all part of "correctly designed") has an estimated lifetime of one hundred years, according to 1960's USAF tests on electrical/vs/discrete electronic/vs/IC circuits.
The fact that many electronics modules are improperly built junk, is something else again. If a vendor supplies a good piece of electronic equipment, it should outlast the boat owner. Most won't do that, because "good" puts things into the range of bespoke tailoring, and most of the market just won't pay for it.

[Richard Kollmann]

Originally Posted by svinshallah

Just a quick question. How does an electronic vs a mechanical thermostat affect anything? It turns on at one temperature and turns off at a lower temperature. What’s the difference? I could see the reliability argument, although the Carel controller is still working fine after 20 years. Thanks for all the good advice over the years.

There are two reasons why I believe available electronic thermostats are less desirable in small pleasure boat refrigeration, One reason is they are not designed for the marine moist air environments and the electronic units are not as dependable as the mechanical snap action standard reliable thirty year thermostats. If and when an electronic thermostat lets you down a simple switch installed in place of thermostat will allow manual control of compressor cooling far as long as you need refrigeration.

There is more to refrigerator or freezer thermostat than just turning compressor Off and On, it also controls the differential temperature efficiency between evaporator and compressor when correctly installed. Icebox conversion refrigeration normally means the system itself is rarely a complete match for the box it is installed in so for this reason the thermostat monitors evaporator temperature and not box temperature. Thermostats controlling evaporator temperature will produce a stable efficient box temperature of less than plus or minus two degrees.

Refrigeration systems using eutectic plates are the exception and control box temperature instead of evaporator temperatures.

[newhaul]

Here is the electronic thermostat I am using and have been using for 3 years still no issues with it.
http://www.ebay.com/itm/Digital-Temp...item2ecca9a4bc

[newhaul]

The only issue I am currently having is convincing myself to spend more on refrigeration than I paid for the new to me boat.
( looking at holding plate systems due to lots of solar and wind power)

[hellosailor]

" One reason is they are not designed for the marine moist air environments and the electronic units are not as dependable as the mechanical snap action standard reliable thirty year thermostats."
I would argue that if a thermostat is not conformally coated, or epoxy potted, the maker has cheaped out and yes, that is not suitable for a marine environment. It may very well be worth doing that additional work, and it may still function properly afterwards.
But mechanical snap action...Sooner or later the contact points are going to pit and arc. Fifty years ago GOOD mechanical relays all used mercury on the contact points to prevent this, but of course, that's illegal these days. Without something to prevent contacts pitting and arcing, I think the hundred-year life of an FET or other solid state device would be more reliable.
Many ways to skin a cat.

[OzePete]

QUOTE from OP:

"I believe XXXXX complete ice box conversion kits costing under $900 with BD35 compressor will set the new standard for most reliable efficient refrigeration. I do not want to rule any other well designed basic systems but for a system needing a BD 35 compressor XXXXX will be hard to beat.

What is the difference between a $900 to $1050 basic units sold now and $2500 unit sold at the same time? Answer is Creative advertising to convince buyer that unnecessary added hardware will be an improvement in performance and reliability over other competitor’s basic *Danfoss BD compressor systems." Should read *SECOP, Danfoss have not made compressors for many years.

Again another attack on those of us building quality products, using obscure statements. (Boy! those Chinese and Italian cheap fridge makers must love you!) Perhaps you might like to name the XXXXX brand, provide detailed performance data and what it provides for the money, then we can do a quick comparison which I am sure will easily justify the addition cost of a quality, not minimal, refrigeration system.

OzePete Ozefridge | 12 Volt Refrigeration Systems

[newhaul]

Ok Richard what system would you recommend for me I have a total of 4 c.f. Icebox to convert and the closest place for the compressor would require at a minimum 14 feet of copper refrigerant lines between the compressor and the box. Looking at 1.5 c.f. Freezer and 2.5c.f. Of refer. Sailboat 400 watts solar and 400 watts wind power. 440 ah house bank.

[Wood]

I'm involved with some construction projects currently in design phase which anticipate using phase change material in building envelopes and mechanical equipment insulation system.

The performance numbers I'm seeing from actual installations and controlled tests are significant.

These material are available in different packing. I'm looking a sheet material which is like a "bubble wrap" with the bubbles [1.5x3"] containing the PCM. The wrap is heavy [~10mil] clear plastic. Thickness is about 0.4". MSDS are benign.

The PCM is manufactured with temperature phase change from ~ -35*F to ~190*F

You can find data at Insolcorp, PhaseChange and others. I have no affiliation.

Cost is around $2.00/sf in quantity

Wondering if any DYI have thought of using PCM to enhance insulation?

[Richard Kollmann]

Originally Posted by newhaul

Ok Richard what system would you recommend for me I have a total of 4 c.f. Icebox to convert and the closest place for the compressor would require at a minimum 14 feet of copper refrigerant lines between the compressor and the box. Looking at 1.5 c.f. Freezer and 2.5c.f. Of refer. Sailboat 400 watts solar and 400 watts wind power. 440 ah house bank.

For cruising in the North West I would recommend a BD35 basic fan air cooled icebox conversion unit. Your present Solar and Wind alternative energy can support refrigeration without running engine. You did not list size of house battery bank I would recommend at least 400 to 600 amp-hr as the converted box is too small for storage eutectic holding plates.

Because this is an old boat the insulation needs to be free of moisture and additional insulation added were possible. For your cruising area two and one half inch of good insulation is expectable. See section on adding insulation on my web site.

I like to promote all of the boat refrigeration industry, this is why I recommend a basic concepts that a boater can use to check prices. Your requirement for 14 ft line lengths is available in some cases while others my price lines out of reason. I try not to single out a refrigeration company on these forums but sense some one might think I prefer China products I suggest you look at wwwnovakool.com/products/conversion_units.htm The duel evaporator unit my be help solving your spillover design.

[newhaul]

Originally Posted by Richard Kollmann

For cruising in the North West I would recommend a BD35 basic fan air cooled icebox conversion unit. Your present Solar and Wind alternative energy can support refrigeration without running engine. You did not list size of house battery bank I would recommend at least 400 to 600 amp-hr as the converted box is too small for storage eutectic holding plates.

Because this is an old boat the insulation needs to be free of moisture and additional insulation added were possible. For your cruising area two and one half inch of good insulation is expectable. See section on adding insulation on my web site.

I like to promote all of the boat refrigeration industry, this is why I recommend a basic concepts that a boater can use to check prices. Your requirement for 14 ft line lengths is available in some cases while others my price lines out of reason. I try not to single out a refrigeration company on these forums but sense some one might think I prefer China products I suggest you look at wwwnovakool.com/products/conversion_units.htm The duel evaporator unit my be help solving your spillover design.

ok thank you I did forget to say that I would be doing a full start over insulation with aerogel. ( I only have 2 inches for insulation on 3 sides) so r25 or so. As I stated I have currently a 440ah Fla house bank ( soon switching to Lfp between 2 and 400 ah depends on shipping cost .)

[Richard Kollmann]

But mechanical snap action...Sooner or later the contact points are going to pit and arc. Fifty years ago GOOD mechanical relays all used mercury on the contact points to prevent this, but of course, that's illegal these days. Without something to prevent contacts pitting and arcing, I think the hundred-year life of an FET or other solid state device would be more reliable.
Many ways to skin a cat.[/QUOTE]

Helosailor, you think mechanical snap action thermostats sooner or later the contact points are going to pit and arc. Would you still think the Danfoss snap action thermostat contacts used on most of these systems won’t last 30 years if I tell you the current across its contacts are never exposed more than 5 milliamps. At compressor speed of 2000 rpm thermostat current is 5 milliamps at 3500 rpm current across contacts is 2 milliamps.