Ice Box Conversion Quandary

[Islanders4Days]

Hey there everyone, I'm new to the site! Nice to meet, and how ya'll doing?

So I have an Islander 36 that has it's OG ice box that I am currently using for storage. I live onboard as my permanent residence and would like to convert the icebox to a proper refrigeration unit, but I am help up by the two options of kits that are available on the market. The two options I'm seeing are the traditional compressor and coil unit and these ASU units that seem a better option but the price definitely puts a damper on my enthusiasm.

Long to short, I'm wondering if its worth spending the extra moola for the ASU, or should I just get the cheaper version?

 

[dlochner]

Welcome to SBO.

I can't speak to the specifics of an ASU or the other units on the market, I can speak generally about refrigeration.

The name of the game in marine refrigeration is energy conservation. On a sailboat the biggest consume of electricity onboard is the refrigerator, thus anything that can be done to reduce energy use will be of great benefit. There are two places to focus on, energy loss through poor insulation or poor hatch seals and refrigerator efficiency. A refrigerator can easily consume 50+ amp hours a day, that is the useable capacity of a Group 31 battery or more. This isn't a big deal if you spend most of your time time tied to a dock and shore power, it is if you are sailing or on anchor for several days.

My advice would be to start with your live aboard plans. If traveling far afield is on your horizon, then spend more money on energy efficient cooling. This might include an ASU or water cooling or other options. If the plans are to stay near to shore power, then go with a less expensive unit and put the extra money towards other boat projects or higher quality beer.

As a broad statement, it will behoove you to look at your entire electrical system and what effect refrigeration will have on it. This is the proverbial project creep, however when adding a large energy consumer it is wise to understand how it will affect the total system.

 

[Hayden Watson]

I am assuming that by ASU you mean the Isotherm ASU "Automatic Start Up" system. From all I can tell that system is no different than any other except that it has an added control module that changes the speed of the compressor depending on whether the batteries are being charge or not.
I build my own albeit fully manual control system that does the same thing for about $50 that I added to my 20-year-old Adler Barbour system. It now runs on about 50Ah/day average. The speed on the Danfoss compressor is controlled by the resistance in the thermostat wire. o-ohm slow, 1500-ohm fast. Slow is good for low amp draw. Fast is good for quick / deep cooling. I also added an Inkbird digital thermostat for $19 that works so much better than the mechanical thermostat supplied typically.

 

[Ralph Johnstone]

From all I can tell that system is no different than any other except that it has an added control module that changes the speed of the compressor depending on whether the batteries are being charge or not.

This is the same impression I get from the the Isotherm writeup below.

The speed on the Danfoss compressor is controlled by the resistance in the thermostat wire.

Where is the stat wire installed ? Is the stat wire a thermistor or ???

I have seriously got to reduce the electrical consumption of the reefer. #1 problem is less than ideal insulation but altering that cannot not be done without major cabinetry alteration of which the changes would be unacceptable. Got to change what I can, where I can and be thankful for whatever saving I can realize. If it doesn't work on a simple project like this, out it goes and back to the drawing board. Keeps the mind active.

 

[Tally Ho]

This is the same impression I get from the the Isotherm writeup below.



Where is the stat wire installed ? Is the stat wire a thermistor or ???

I have seriously got to reduce the electrical consumption of the reefer. #1 problem is less than ideal insulation but altering that cannot not be done without major cabinetry alteration of which the changes would be unacceptable. Got to change what I can, where I can and be thankful for whatever saving I can realize. If it doesn't work on a simple project like this, out it goes and back to the drawing board. Keeps the mind active.

That data sheet on the ASU is for a seawater cooled refrigerator. The Adler-Barber unit on my boat is air-cooled.

Greg

 

[Hayden Watson]

This is the same impression I get from the the Isotherm writeup below.



Where is the stat wire installed ? Is the stat wire a thermistor or ???

I have seriously got to reduce the electrical consumption of the reefer. #1 problem is less than ideal insulation but altering that cannot not be done without major cabinetry alteration of which the changes would be unacceptable. Got to change what I can, where I can and be thankful for whatever saving I can realize. If it doesn't work on a simple project like this, out it goes and back to the drawing board. Keeps the mind active.

If you look at the specification you will see that speed is controlled by the resistance of the thermostat circuit (T-C terminals)
bd50f_101z0203_r134a_12-24vdc_12-2022_desd100q522.pdf (secop.com)
Here is a video about speed control. The Merlin II is a plug and play unit but costs $160.
video on Frigoboat speed control
If you ditch the mechanical T-stat and install an inkbird it will have 0ohm resistance and the compressor will run at 2000-rpm with reduced battery comsomption. If you want to get fancier, you can install a 1500-ohm resistor in parallel with a toggle switch in the Y or C wire. If the switch is on you have o-ohms and 2000-rpm. If the switch is off, you have 1500-ohm and 3500 rpm.

I then added a pwm fan controller to the case fan which enabled me to put a variable speed fan to cool the condenser. In cooler climates less cooling is better because you can super-cool the refrigerant which greatly reduces the efficiency.

On my 1988 C30 with just the original icebox without any modifications the lid or insulation, I reduced the consumptions from 80-100Ah per day to 50Ah. It also now runs completely silently so that I can only tell that it is running by holding my hand on the compressor and feeling the slight vibration and air flow from the fan.
Another benifit is that it eliminated the short cycling. With the mechanical Tstat, it would run 5-min on 10-min off 24/7. With the Inkbird, it runs for about 30-minutes than off for several hours.

 

[Hayden Watson]

That data sheet on the ASU is for a seawater cooled refrigerator. The Adler-Barber unit on my boat is air-cooled.

Greg

The ASU has a control for seawater cooling but also works with air only cooling. It will work on your AB. If you look at your compressor, you will see the normal black control box that is used on every other system is tucked behind the silver AB controller which does nothing more than change the Tstat to a phone jack and provide the LED diagnostic light. Many users have just chucked them when they go bad and made the connections straight to the black box. That box is one of the reasons that AB is so much more expensive than all of the other brands.

 

[jssailem]

Welcome to the SBO Forum.
Live-a-boards take several paths.

• The ones who are not leaving the marina, often search out an AC powered small refrigerator from Walmart. One the looks similar to the corner refrig in so many 3rd year college dorm rooms. With constant AC power they are inexpensive and serve to keep food and beer cold.
• If your boat is going to be sailed away from the marina then the options are varied. You can go the ice box conversion route. The above info is excellent. SureMarineService in Ballard is a good source equipment and ideas on product.
• You can explore the Dometic line of electrical Coolers. Or pack ice in a Yeti. The small one I carry on board keeps the drink cans cold on a bag of ice for 6-7 days.
• There is also the idea of a build in mini refrig/freezer. NovaKool builds various sizes. You can check out their product line at About — Nova Kool Manufacturing ULC They use DanFoss compressors. Are fairly priced. Run on DC/AC. This is the route I took. Quick install. I took out 3 drawers and it fit nicely in the space. This is a Freezer model that I set the temp 36

Check out the options at the upcoming Seattle Boat Show. There will be discounts available and several suppliers selling their wears.

 

[Hayden Watson]

There are also a bunch of very nice stand-alone 12v fridge/freezers. I have both the ice box conversion and a chest freezer in my C30.
I added this last year after I built a 560Ah LFP battery bank. in two 10-day cruises last summer we averaged 100Ah consumption per day with the fridge, freezer, hydronic heater for a couple of hours each morning for hot water plus all normal loads.
We use this unit as a -4ºC deep freezer and it cost less than $300. We also use it in our motorhome and it has been running flawlessly for the past 3 months.

 

[Ralph Johnstone]

If the switch is on you have o-ohms and 2000-rpm. If the switch is off, you have 1500-ohm and 3500 rpm.

Any idea what the theory is behind greater thermal efficiency at lower compressor rpm's ? Can't see lower gas velocities and lower piston ring friction amounting to much.

 

[Terry Cox]

Our 1991 boat came with dual WAECO 12VDC systems; freezer and refrigerator. Both have performed quite well over the years. I keep them on 24/7 and depending upon use will cycle about every ten to fifteen minutes or so. Power to run them comes from two 8D house batteries rated at around 250 AH each. The refrigerator compressor unit died about seven years ago, so replaced it with same, basically plug and play.

During our extended (two month plus) cruising periods, I run our 60 AH+ generator for about one and a half to two hours every other day to top off the house bank where we consume about 80 to 120 AH during that 48 hour period, which consists of the refrigeration systems, as well as operating the various other boat systems.

Overall, our arrangement has worked well for our cruising plans. Whether it will work for you depends upon what plans make up how you intend to use your boat. A fellow skipper who lived aboard and cruised his boat for many years had the same system, except one unit, which seemed to work for him.

 

[Hayden Watson]

Any idea what the theory is behind greater thermal efficiency at lower compressor rpm's ? Can't see lower gas velocities and lower piston ring friction amounting to much.

The energy required to do work is not perportionl to the increase in output. Think of it like walking vs running. How far can you walk without stopping. How far can you jog without stopping? How far can you sprint without stopping? Low and slow takes longer but requires less total energy to be used.
That is why the smart refer controllers run on high and cool to a colder temperature when you are charging and go slow and efficient when on battery.

 

[MikeHoncho]

If the ASU part is referring to Isotherms blue box that attached to the compressor…….I’d pass. I went through two of them due to inadequate temp control and abandoned it. The company stepped up though and sent me a standard thermostat that I had to replace. Not worth the extra $150.

 

[NYSail]

I run my refrigerator/ freezer continuously with no power issues thanks to 400 watts of solar that typically has my batteries topped off by 11:00 am. Also the p/o added an electronic thermostat that over rides the factory dial which I’m sure adds to some efficiency. Insulation on my freezer/refrigerator is inadequate but to add more would be significant for cabinet demo. Btw we have a simmer slip, however stay away on anchor for most of the summer with trips of 2 months and never an issue.
Good luck
Greg

 

[FastOlson]

I do sometimes wonder how many of us (me, too often) are seeking a solution that we can install or plug in, and be totally done !... when the first major component of lower amp draw is determined by insulation.

When I first set out to install 12 volt refrigeration in our boat I was aware of several articles/narratives about this, and did add more insulation to the sides and the lid. I believe that this made a noticeable difference in 'run time' and both our fist Frigoboat (ten years) and newer Isotherm run less than half time.

I have not tried to measure their separate fridge amp draw over a day, but we can anchor out with all the attendant lighting (led) and fridge running 24/7, and still have about 12.4 to 12.5 volts on the house bank meter... and start the diesel with ease to get under way. We have one "house bank" of two Trojan T-125+ six volt wet cell batteries.
No TV or stereo, however. No solar or wind power, either. Ever boat will be a little different, so our amp-hour experiences may be only somewhat helpful.

 

[Leeward Rail]

There are also a bunch of very nice stand-alone 12v fridge/freezers.

That is my current plan. A few of them come with LG compressors. Ripping one apart for a DIY icebox conversion is my current thinking.
Even as standalone they make real sense.

A dockmate uses 2 of them (fridge and freezer). Unless he tries to keep ice cream hard, the power consumption has been low enough for his solar setup.

All sorts of ways you could do a pseudo built-in install with one, without tearing one apart. We have a locker that is darn near designed for it.

the first major component of lower amp draw is determined by insulation.

In the non boat world..specially housing, the traditional low cost of energy has tended to make the insulation a afterthought. If they insulated homes, freezers, fridges, coolers, better, the energy needs for heating an cooling would be low

NetZero building in Antarctica ? Ice Cooler that lasts many days ? Thermal mug that keeps my drink hot/cold for 12 hours ? Easy peasy really.

 

[Leeward Rail]

All in favour of @Hayden Watson having his own sub forum for this topic, say Aye !

 

[Hayden Watson]

That is my current plan. A few of them come with LG compressors. Ripping one apart for a DIY icebox conversion is my current thinking.
Even as standalone they make real sense.

THis is what I plan to do if my 25-year-old Cold Machine ever totally dies. I have all of the equipment to make the connections with either compression fittings or silver solder and have the vac-pump, gauges and sniffer needed to get it all up and running. Over the years, my AB has quite on me at least 4-times and I have gotten pretty good and getting it up and running again. A dead compressor would be its death-knell at which point I would buy another freezer like the one I have and rip it apart for the guts.

 

[Leeward Rail]

I have all of the equipment to make the connections with either compression fittings or silver solder and have the vac-pump, gauges and sniffer needed to get it all up and running.

I have done automotive AC professionally and have all that gear. I haven't dealt with small refrigeration systems, but it shouldnt be a big deal once I read up on the components used. I assume gradually filling the system using a temp gauge to determine capacity would work.
What refrigerant are the small portable units using ? 404 ?
Here's hoping I can find one with valves installed so I can use a recovery system.

 

[Hayden Watson]

I have done automotive AC professionally and have all that gear. I haven't dealt with small refrigeration systems, but it shouldnt be a big deal once I read up on the components used. I assume gradually filling the system using a temp gauge to determine capacity would work.
What refrigerant are the small portable units using ? 404 ?
Here's hoping I can find one with valves installed so I can use a recovery system.

The one I got was 134a. You really do not need gauges except for the valves. These systems are so small, and most do not have a true expansion valve. They mostly are capillary tube expansion. Given that, the height of the frost line is the most critical indicator of proper charge. Recovery can be done but my AB system can be fully recharge from a vacuum two to three times on a single 12oz can.