Which new refrigerator system?

[Palarran]

I wouldn't use anything but copper. You'll have a bigger problem with leaks using stainless or aluminum. Copper immersed in fresh water, whether it's raunchy or not, is going to last a long time. 12 feet there and then back is a lot of tubing considering you'd have to immerse a whole lot in the water. When we do geothermal pond loop installations we take 300' coils of plastic pipe and seperate the coils horizontally about one inch per row in order to allow water to flow around it. If I was experimenting with this I'd probably take a 50' roll of either 3/8 or 1/4" tubing and seperate the rows with a spacer, cut a hole in the top of the tank and drop it in. Braze the lines in place and see what happens to the head pressure. Of course, someone with engineering skills and time could figure this out better. All I know is it's better to have more subcooled refrigerant then have saturated liquid at the metering device.

[Palarran]

I should really think about this more before I post a response. The easiest way to do this is if you have a current air cooled condenser, just cut it out, run the same size lines to the tank as are already connected to it, and just drop the existing condenser in the tank. I'd think you'd need at least 50 gallons of water to have a big enough heat sink.

[Christian Van H]

Does anyone have info on using freshwater to cool a SuperColdmachine via the normal water cooling conections? Diagrams? Articles? Experts?

[s/v Jedi]

The max. distance for a Frigoboat keelcooler is 5' so 10' round-trip. Why not use the Frigoboat and mount the keelcooler into the tank? That's how metal boats do it (with hull part of the special tank filled with coolant). Just have to find a spot for the very small compressor unit (no air-cooling so small) within 5'.

cheers,
Nick.

[George Elliott]

The installation I did uses 25' of 1/4" for the hot gas discharge which I sweated into 5/16" for the liquid return line, it's about 20' long. Losing the pump was a blessing not to mention not having to clean the sea water strainer or clean barnacles out of the hoses. if there's a downside I've yet to encounter it. Cheers George

[Celestialsailor]

Originally Posted by George Elliott

The installation I did uses 25' of 1/4" for the hot gas discharge which I sweated into 5/16" for the liquid return line, it's about 20' long. Losing the pump was a blessing not to mention not having to clean the sea water strainer or clean barnacles out of the hoses. if there's a downside I've yet to encounter it. Cheers George

George...How long have you been using it and what is the ambient temperature where you are? See where I'm going with this?..

[Richard Kollmann]

Water cooling a small refrigeration system condenser will not produce the reliability and consistent performance of fan cooled units do to variables involved with water temperatures and refrigerant pressure control. I have modified three Danfoss condensing units in the past by putting tubing in fresh water tanks to act as a condenser and found two required changes to the length of tubing in tank to achieve correct head pressure. One of these boats spent winters in Bahamas and summers in the north. Each year I would add refrigerant when he went north an remove refrigerant when he came south. After five years the third boat’s water tank that was part of the aluminum hull had developed electrolysis pitting in water tank hull plate. The only water cooled condensing unit with a BD compressor I know of that has not experienced failures from electrolysis is Adler Barbour’s SCM units.

I believe it is difficult to improve on a Danfoss BD compressor fan cooled condensing unit, when this unit that is well designed, properly installed and set up correctly.

[Celestialsailor]

Well...thats good enough for me. I guess if it works, don't fix it saying applies here.
Richard...on the air cooled Danfoss units...Would a fan with more cfm's help any?

[hellosailor]

Richard, two questions.
"do to variables involved with water temperatures "

So, is Frigoboat a fraud? Or do they do something to accomodate this with their keel coolers?


And if the variation in water temperature causes problems, then wouldn't the larger variation in air temperatures cause a similar or great problem with air cooled systems? Or is it enough that the fan is thermostat controlled?


What's missing from this picture?

[Richard Kollmann]

Hellosailor, I do not recommend any type of water cooling on compressors smaller than 1/6 HP. I have no information that would question the Btu performance of Frigoboats VECO keel cooler. For more information on my opinions see FAQ 33 on my web site.

Information received on VECO's cooler would indicate that BTU performance is good with seawater temps up to 89 degrees F using BD35 compressors. I do believe that Frigoboat has a quality control problem with VECO and a serious problem with debris plugging capillary tubes. If you want more information on this see article Keel Cooler and Boat Owner’s Nightmare on page 2 dated 31 May 2008 on my forum.
http://kollmann-marine.com/phpBB/viewtopic.php?t=2062

[Christian Van H]

Richard, Am I then to understand that, although the Adler-Barbour SuperColdmachine offers both air and water cooling, you WOULD NOT ever use the water cooling feature? I know that although we have only spoken about refrigeration efficiency, adding an electric saltwater cooling pump draws additional amps as well...

[Celestialsailor]

Originally Posted by Christian Van H

Richard, Am I then to understand that, although the Adler-Barbour SuperColdmachine offers both air and water cooling, you WOULD NOT ever use the water cooling feature? I know that although we have only spoken about refrigeration efficiency, adding an electric saltwater cooling pump draws additional amps as well...

From the way I'm understanding this...the issue is electrologist. But as mentioned earlier...if you plumbed it to a 20+ gallon water tank, wouldn't this work?

[hellosailor]

There's a lot to read there, Richard, thanks!

By the way, where DO you get nitrogen for working on refrigerant/ac systems? My local compressed gas guys have it--but have no idea what kind of fittings or adapters would be involved, in my case to get it down to a R12 system using conventional fittings for R12.

[Richard Kollmann]

Van, Adler Barbour’s SCM was a well designed system and was top of the line because of their continued product improvements. Today small boat refrigeration is experimental and units are sold as expendable items when it fails by another. The Super Cold Machine is an air cooled system with a very small supplemental water condenser. High pressure gas first interiors air cooled condenser then passes through a small water cooled condenser. When cabin air is much warmer than seawater then seawater cooling can temper still warm refrigerant. When water and air temperatures are right this system is efficient. There is a controlled test of the SCM’s performance on page 5 of my 12/24 volt refrigeration manual. With seawater temp at 80 degrees and cabin ambient air temp at 78 degrees, 18.3 amp-hrs is consumed in this test for one test cycle with both fan and water pump running. One identical cycle with fan cooling only 10.9 amp-hrs. Water cooling and no fan 23.9 amp-hrs test stoped at one third cycle time of others.. The added power to drive the pump offsets any real benefit in warm seawater, this is why most boaters keep pump turned off south of latitude 30N.

Celestialsailer, There are a number of reasons I would not run a refrigerant copper tube in a fresh water tank such as poor refrigerant control., possible poor oil return, not having the correct length of tubing to maintain correct pressure differential. Ounce heat is deposited in water how can it be disposed of before additional heat is added. How can condenser tubing in a tank in motion be supported to prevent tubing fractures from work hardened copper involved in water turbulence. In a glass or wood boat electrolysis in a fresh water tank is not something to worry about I would be concerned about bastardizing my refrigeration unit.
Your efforts are best directed to improving the installation of present air cooled unit.

[George Elliott]

Sure I see where you're going. The sea water temp is about 83 and the cabin is often 90 in the day, the tank is 25 gal and if you read all the posts you'll see that the 12v system is part of the freezer system which also has a mechanical compressor. So the danfoss doen't cycle full time, maybe 2/3 time. But I don't seem to be seeing hot temps in the tank even with a small tank. Al in all i think it works a treat. George