Which new refrigerator system?

[mestrezat]

I'm the guy that started this post.

I finally went with a Cool Blue system from Technautics. Promises to use only 2 amps. I'm in the final stages of installation but during the initial cool down last night, it was using only about 3 amps and it kept going down over the night.

We installed the divider this afternoon to separate the box into dedicated freezer and refrigerator sections. It went relatively easily.

I had few questions during the installation but in the calls I made to Technautics, Randy--president of the company--answered them. Great guy. I'd talked to him at the past few boat shows here in Seattle.

We'll be firing it up tonight and loading it up with food. I have two different thermometers I'll be putting in the unit to monitor the temperature in each side. I'll let you know how it does.

So far, so good.

[bobfnbw]

Mestrezat, thanks for the update, and let us know how its going. Thanks.

[James S]

CooooL.....
Looking forward to your report.

[Therapy]

Originally Posted by mestrezat

I'm the guy that started this post.

I finally went with a Cool Blue system from Technautics. Promises to use only 2 amps. I'm in the final stages of installation but during the initial cool down last night, it was using only about 3 amps and it kept going down over the night.

We installed the divider this afternoon to separate the box into dedicated freezer and refrigerator sections. It went relatively easily.

I had few questions during the installation but in the calls I made to Technautics, Randy--president of the company--answered them. Great guy. I'd talked to him at the past few boat shows here in Seattle.

We'll be firing it up tonight and loading it up with food. I have two different thermometers I'll be putting in the unit to monitor the temperature in each side. I'll let you know how it does.

So far, so good.

Thanks for the update.
Sounds great.
2 AMPS...........WOWZERS!!!!!!!

[mestrezat]

The freezer section was at 0 degrees this morning and the frig was at 33. Running at 2.7 amps. Not bad.
Installation all in all was painless. I'd recommend this unit to anyone.

[Therapy]

Originally Posted by mestrezat

The freezer section was at 0 degrees this morning and the frig was at 33. Running at 2.7 amps. Not bad.
Installation all in all was painless. I'd recommend this unit to anyone.

Fantastic!!

Thanks again.

[Richard Kollmann]

mestrezat, I am trying to collect performance information on the new compressor used on Technautics Cool Blue ice box conversion units. I assume your tests on the Cool Blue are done in Port Townsend WA. I have a good performance history on the Cool Blue with the Danfoss compressor but nothing on your compressor’s in-service performance. If you could answer a few questions it will help me with this new compressor performance study.

• That is size of interior of box in cubic feet or dimensions?
• Approximate amount of insulation and type if known?
• Approximate ambient air temperature in boat during test?
• Approximate seawater temperature outside boat?
• Starting with holding plate at ambient cabin air temperature how long does it take to lower box temperatures to the reported 0 freezer and 33 degrees in refrigerator?
• In what position were the two speed switches IN 1 and IN 2 in, during temperature pull dow? If both were in O (OFF) position compressor speed will remain at 1500 rpm.
• The real indicator of energy efficiency is daily amp-hours consumed. Do you have a way to record amp-hrs? If so how many amp-hrs are consumed in 24 hours?

[Roy M]

Richard Kollman: YES!!! Thank you! This is precisely what I wish to know, as well. Everything else is subjective interpretation. What you have asked allows others to compare apples to apples. Otherwise, this thread will go on forever with "expert knowledge" and personal recollection of unmeasured data and conditions. When we get the data that Richard has requested, on a variety of brands and options, anyone will be able to make a truly informed decision based on data that can be double checked. The scientific method rears it much-maligned head and begs the question, "Which unit gives me the biggest bang for the buck (and amp-hour)". Thank you again, Richard!

[Extemporaneous]

Originally Posted by Roy M

I'm about to build my new reefer/freezer, using materials I purchased from Bob Van Ness, AKA Captain Frost (http://captainfrost.com/). His direction has lead me to my present design which uses a Bitzer compressor, 12 volt direct drive motor, and standard cold plate technology, just like Glacier Bay's stuff, only cheaper priced. The box technology is supplied by Rparts (RParts: Refrigeration Parts Solution). Their website provides all info. Bob has demonstrated to me, and many others, the value of using a powerful motor and compressor to quickly chill down the cold plate. Over a 24 hour period, fewer than half the amp hours of battery capacity are spent on refrigeration than ANY competing brand. This, of course, implies that your box is well insulated using vacuum super-insulating panels, 1" thick equalling 6" of polyurethane foam. The systems are robust, serviceable, and quiet. They cost more than Adler Barbours, but use half the juice over a 24 hour day cycle. Check out the Rparts site and the Captain Frost units

A consequence or our current economy?

[Richard Kollmann]

Roy, I normally would not post a response to someone who has already purchased a refrigeration system for his boat but to say “Half the juice over a 24 hour day cycle” will mislead others who may be considering buying refrigeration. The only way anyone could correctly justify this statement is to have compared the System Coefficient Of Performance (SCOP) of each system you are saying is 50% less efficient. My information on these shaft driven systems is they are less efficient and require frequent heavy maintenance. If someone has a large ice box to convert with a very large battery bank and runs an alternator more than one hour per day or keeps their boat North of latitude 35N the shaft driven compressor will perform well. Search back on boating forums and ask live aboard boaters questions about this type of a system will give a better look at their overall performance. Also ask why Glaser Bay was not be successful with this type unit. I believe Calder tried this system in one of his boats, see what he thinks about them now.

[bobfnbw]

All this is important Richard, but what I also would like to know is how well these units keep the temp at the set rate. What flucuation of temps do you see. How high does it get in the freezer and fridge?
If the freezer cycles between 0 and 30 deg F, for instance that system would be less attractive to me than one that stays at or around 0.
That is one issue I have with holding plates is that they seem to fluctuate in tems more than a condenser system does.
I would love to see real world numbers on this.
Bob

[Gashmore]

Statements like "it draws 2.7 amps" is like giving baseball scores "3 to 1, 5 to 3 and 7 to 0" without giving team names.

I still question the whole idea of pairing a low capacity compressor to a holding plate. The idea of a holding plate system is to use a large compressor to freeze down the plate rapidly when energy is cheap, i.e. the engine is running and the alternator is generating power. The plate then absorbs heat while energy is not available or more expensive. i.e sailing.

Even at maximum speed, when it is least efficient, a small compressor will take a long time to freeze the plate. At lower, more efficient speeds when it might use only 2 or so amps it may have to run almost as long as an evaporator system. In that case the holding plate is just a bulky evaporator taking up space in the box.

[Roy M]

I just started demolition for the future site of the freezer/reefer, and have positioned the compressor and motor and its accessories. One of these days I will complete the installation and pass the specific data along. If I'm wrong, I can remove the compressor and replace it with another. But that will be after running a number of 24 hour ampere consumption tests, which for me, beats all the other theoretical stuff for my purposes. If I am happy with the results, that will be reward enough. We'll see what happens.

[gbanker]

Agree with Richard Kollman (although we have friends who went the "Engle" route for a freezer and are quite happy so far). Forget engine run and/or holding plate systems (IMHO). We have a Frigoboat freezer and refrigerator and recommend that system.

[Richard Kollmann]

Holding Plates and Box temperatures

A good boat freezer needs an evaporator that surrounds the frozen food product in order to maintain food product taste for more than two week. Using 134a refrigerant and holding plates rarely results in a four month boat refrigeration freezer.

Maintaining a refrigerator’s box area temperature using a standard evaporator at a tolerance of plus or minus one degree is possible because compressor cycles ON and OFF by a thermostat controlling evaporator’s temperatures and not box temperature. Electrically driven compressors need a time differential between stopping and starting up to allow for refrigerant pressures to equalize reducing motor starting torque. Thermostats can have adjustable or fixed differential settings. Most icebox conversion refrigeration units have a differential setting of 10 to 18 degrees allowing a large evaporator temperature swing while box temperature swing is only a couple of degrees.

Eutectic holding plates are a different type of evaporator and serve only one purpose and that is to store surplus energy when it is available. The only evaporator more efficient than an aluminum thin plate would be a copper thin plate unit. Heat transfer in thin plates is faster because they are excellent conductors of heat. With a thin plate evaporator system for the refrigerator box’s heat to be absorbed by refrigerant it only needs to pass through a thin metal heat conductor. When using a eutectic holding plate heat must move through stainless steel plate, then through a liquid and or ice before it reaches the copper evaporator tube inside plate.

Major efficiency loss occurs in a holding plate during the formation of ice build up on evaporator coil. Because of the poorer heat conductive of holding plates more energy at lower temperatures is need to freeze eutectic solutions solid. Do to the random placement of coils in holding plates and different mixes of eutectic solutions actual performance will vary. Temperatures inside a typical zero degree F holding plate will resemble these figures just before compressor stops, if system is designed for 134a refrigerant. Refrigerant temperature inside plate coil -20 F., Exterior plate surface -10 degrees. Once a zero degree plate’s solution is frozen only ½ a Btu per degree per pound of solution is stored below the eutectic freeze point of zero degree F.. This means plate temperature will quickly rise to zero degrees F when compressor stops. If only water is frozen in a plate it will maintain 32.degrees as long as there is ice in water tank. Eutectic solutions even the so called true eutectic have a rising temperature glide. The rate of temperature increase of eutectics depends on frozen liquid solution quantity in plate. At standard day temperatures using a glycol based eutectic solution of one gallon of zero degree mixture per cubic foot of freezer box frozen to 15 degrees below zero, will produce a temperature increase over 24 hours from zero to +22 degrees. Box temperatures will vary depending on distance away from plate and height above box bottom.

Not only are the standard evaporators better in controlling box temperature more efficiently than eutectic holding plates but they can also provide lower box temperatures when using 134a refrigerant.