Refrigeration: 12vdc Holding Plate vs Evaporator

[Richard Kollmann]

Seawater temperature determines degree of condenser heat removal by controlling refrigerant liquid sub cooling pressures. When liquid pressure is too high or too low evaporator superheat will affect system performance. Super Cold Machines all ready do have a switch to stop water pump when seawater is too warm or too cold. Most boaters who have these water pumps do not use them because: filtering water is a problem, Water pump reliability, and units destroy energy efficiency of the newer variable speed Danfoss BD compressors.
All Adler Barbour units now use the BD50 compressor but if you watched my slide show and found the BD35 compressor speeds more energy efficient there are other conversion unit manufactures that use the smaller compressor.

[Cheechako]

I've had both 12v holding plate and evaporator...a couple of times at least for each. I lean toward the holding plate, bu t wouldnt rule out either. It seemed to me that the holding plate unit would handle cooling things down better when you put a fresh load of food in. my friends had a frigoboat keel cooler model and sailed the pacific with it. They liked it alot. The unit that comes on with a rise in voltage is intriguing, but more to go wrong I suppose. That is a huge cold box youve got. You should consider freezing 4 or 5 gallon jugs and putting them in the bottom before you start a vacation!

[onestepcsy37]

you might want to rethink the size of the box; we started out with a 6 cf but i've since 'reduced' it to 3 cf by putting removable insulation blocks in the bottom. just doing the east coast u.s. and the bahamas we find that sufficient. uses a lot less amps too. one 135 watt solar panel keeps it running, and the fridge is the most power hungry device we have on the boat.

we went with an adler barbour air cooled unit. it has the capability of adding a water pump but i haven't found it necessary and richard kollman convinced me it probably wouldn't do much anyway. the evaporator box serves as the freezer and seems adequate for our needs. we live in florida.

the only down side is the defrosting part....

[skipmac]

OK. Bought the book, read the website. Looked at performance data and the Practical Sailor tests, spoke to boat owners that liveaboard/cruise in the Caribbean and all point to air cooled Danfoss system as a better option than holding plates.

Am planning a system for upgrading my old box but to avoid a charge of hijacking will post on a new thread.

[deckofficer]

I've used these for off the grid homes. How does 12 cubic feet (6 for fridge, 6 for freezer) and daily 24 hour consumption at 90 degrees ambient for all of 0.47 Kw/h (39 a/h @ 12 VDC) sound? I don't think it can be beaten other than home brew. If you were on the grid and cost was 0.10 Kw/h, your monthly cost would be $1.43 to give you some idea how good these units are. Even in poor solar conditions (2) 80 watt panels would always give more than enough with a good battery buffer, and that is based on 90* ambient, much better for cooler climates.

Sun Frost Refrigerator specifications

[malbert73]

Originally Posted by onestepcsy37

you might want to rethink the size of the box; we started out with a 6 cf but i've since 'reduced' it to 3 cf by putting removable insulation blocks in the bottom. just doing the east coast u.s. and the bahamas we find that sufficient. uses a lot less amps too. one 135 watt solar panel keeps it running, and the fridge is the most power hungry device we have on the boat.

we went with an adler barbour air cooled unit. it has the capability of adding a water pump but i haven't found it necessary and richard kollman convinced me it probably wouldn't do much anyway. the evaporator box serves as the freezer and seems adequate for our needs. we live in florida.

the only down side is the defrosting part....

Agreed. My current box is designed to be 1/2 full of ice as it is greater than 8 cu feet. I will add tons on insulation to the inside of current 3-4 inch insulated box to make it smaller and more efficient, and until it "looks the right size"
I also intend to mold a block of foam as a filler for most of the time when we don't need full capacity, which can be removed for when we do.

[aland3800]

Listen to Mr. Kollmann, buy his book, you will thank him. My AB runs great because of him and the wealth of information.

[Reality Check]

I would strongly recommend you spend the $$$ you are considering for the water cooling effort and spend them on a reasonable Solar system... you will be much happier particularly if you do cruise in the warmer Waters.

I only know of a few cruisers down here that still attempt to use water coolers to help save energy.... cost too much and when water temps reach in the 80's they are useless and take more power to operate than they give in benefit. Go solar with a good MMP regulator and you will probably not have to use your engine to generate power to operate the frig/ Frez... I also use an AB and it has worked well with 2 85 watt panels for probably 90% of the days I've been out... which is a couple of years.

[Cheechako]

Originally Posted by malbert73

Agreed. My current box is designed to be 1/2 full of ice as it is greater than 8 cu feet. I will add tons on insulation to the inside of current 3-4 inch insulated box to make it smaller and more efficient, and until it "looks the right size"
I also intend to mold a block of foam as a filler for most of the time when we don't need full capacity, which can be removed for when we do.

Just noticed you have a Luders 33. My buddy-boat friends in Mexico had one of those . Sweet boat.

[malbert73]

Originally Posted by Cheechako

Just noticed you have a Luders 33. My buddy-boat friends in Mexico had one of those . Sweet boat.

Thanks! I agree. Everyone loves their boat, but this one really sails sweetly. Some boats just seem to have a "soul"

[centralyachts]

Richard is absolutely smack on the money. Having owned an Isotherm 12v system with 'holding plate' I learned quickly that this was a daft idea. The surface area of the plate is not big enough to quickly pull down the box. The only advantage of a eutectic holding plate system is to store 'coolth' (energy, or lack of it). In a 12v system this energy should be stored in the batteries, not the plate.
Buy a Frigoboat system with keel cooler and large flat plate evaporator - that's the best outcome...

[Cheechako]

Originally Posted by deckofficer

I've used these for off the grid homes. How does 12 cubic feet (6 for fridge, 6 for freezer) and daily 24 hour consumption at 90 degrees ambient for all of 0.47 Kw/h (39 a/h @ 12 VDC) sound? I don't think it can be beaten other than home brew. If you were on the grid and cost was 0.10 Kw/h, your monthly cost would be $1.43 to give you some idea how good these units are. Even in poor solar conditions (2) 80 watt panels would always give more than enough with a good battery buffer, and that is based on 90* ambient, much better for cooler climates.

Sun Frost Refrigerator specifications

Interesting. Do you know what compressor they use? Apparantly they are 120v/12v. Are they really any different than others? Are those actual usage or their advertised numbers?

[engele]

We fill up the extra space in our box with the mylar bags that you can get from Starbucks full of coffe for company parties. They are like boxed wine bladders, but they have a screw lid and are smaller. One cool advantage is that you can fill them with water and freeze them if you like, or blow them up with air to fill up the extra space on top of your box. Probably not as good as foam insulation, but it does appear to help.