Following is a summary of "Refrigeration" discussion as it appeared in Yahoo Groups...

Cervezas in Everglades City, FL








From Dennis on Sweet Dreams

I am still contemplating upgrading our refrigeration system on Sweet Dreams (Hull 63, 1975). I just emptied the boxes and measured the refrigerator and freezer and was amazed to learn the overall internal size is 16.4 cubic feet. The insulation under the freezer appears to be a course blown non-incapsulated insulation. My question is if anyone knows what is in the side insulation. The box is still in perfect condition and I'm loath to tear it apart to re-insulate. I'm thinking of adding more to the inside and encapsulate that rather than start from scratch. Before I decide, I would like to know what I have now. Doug, do you recall how the refrig/freezer was constructed on the earlier Whitbys? Your information on tankage, rigging, etc. has been invaluable.


From Derek & Darlene on Ocean Dove


One if the first jobs I did went we bought Ocean Dove #328 was to remove the old Grunert refrigerant system and cold plates. I spoke with Marvin Nye at E-Z Kold about replacing the old Grunert system, he suggested that I install two systems, one single cold plate unit (EK-12CPAW) for the refrigerator and a second double cold plate unit (EK-12CPAW-2) for the freezer. Each unit has it’s own air/water condenser/compressor, water pump and controls. I liked this ideal as the two systems use the same compressor and parts and with two separate systems there is always a backup if one fails.

I could refit the refrigeration system in two stages. I am at present half way through the upgrade. This spring I installed the single cold plate in the refrigerator and it has kept my beer cold all summer, it draws about 6.1 amps went running. I will buy the second unit this winter to be installed next spring.

I have not upgraded the insulation but did replace the door seal.

Good luck on your refrigeration.


From Russ & Jane on Luna  

We cut out our ref/freezer box and rebuilt entirely new boxes. It is not a job I recommend. We posted photos of the inside foam at The insulation you see underneath is what you will find on all sides. It is pretty spotty in some places. If you can give up the space I would recommend adding insulation inside, mostly in the bottom. I believe several folks have done this. If you have any other questions feel free to contact us.


From Derek & Darlene on Ocean Dove


The EZ Kool refrigeration system is air or/and water cooled and is designed for the warm waters of the Caribbean. They have an air cooled condenser with fan and a water cooled condenser with a small pump. The pump can be switched off so the unit is just air cooled. They use Danfoss compessors and are designed for EZ installation by the owner. The system is pre-charged with R134 refrigerant and have quick connectors on the gas lines. The cold plates are made of Stainless Steel. The compressor units have a small foot print and two units will fit in the same spaces as the old Grunert. 


The 2008 price in Canadian $ was








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From Tom on Lone Star


Regarding your refrigeration and in response to some of the other suggestions:  I removed our old Grunert after many years of hassles & many dollars spent.  I added foam board insulation to the bottom of the freezer, reducing it's volume, then sealed it with a new formica type bottom & some good caulk.  Initially, I installed an EZ KOLD two plate system (water cooled) in the freezer and moved cold air to the fridge via a thermostatically controlled small (computer type) fan.  After a year or so, I added a second compressor & plate dedicated to the fridge area.  Marvyn  from EZ Kold will make custom sized plates if you ask, but make sure you can fit them in the box.  The one thing I did not do, and wish I had, was to make the fridge system water cooled.  It is only air cooled, and  I had a big plate made, so it takes a while to run through a cycle, but all is good.  

A few observations, the Danfoss BD 50compressor is EXTREMELY sensitive to it's freon charge.  If your unit seems to be pulling more amps than you think it should, let some gas out.  A gauge helps.  Also, many times, when my unit failed to cool, it was simply not enough voltage in the battery bank. I now have four 4D's for a bank.  Even with that many batteries, on a night crossing, with the auto pilot & radar working;  the voltage will drop for just a few second, while the auto pilot is working, and the compressor shuts down automatically.  This is not a problem once you realize what is happening.  It restarts once voltage is good, but you may have to turn something else off to maintain proper voltage. 

In St Martin, Frost Refrigeration was utilizing a Danfoss BD 50 with a large fan / evaporator plate  combo that cools very efficiently.  With that system, you may only need one compressor. 



From Dennis on Sweet Dreams


Fortunately, our Grunert 120 volt AC unit has never given us a problem since we bought Sweet Dreams in 2002.  The only issue is running the genset twice a day for 2-3 hours.  This precludes leaving the boat at anchor or on a mooring while traveling.  It also means extensive maintenance on our 34 year old Onan genset. 


I hate to remove something that is working, but I think I will add insulation and a Danfoss DB50 unit and see how things work.  My holding plates are huge (23" x 13" x 2" each), but the air/water cooled compressor unit is only 1/4 hp which seems way undersized for the size of the frig, especially in the tropics.  Once I add the DC refrigeration I will also need to upgrade my battery amp hours and install extensive solar panels.  Now we're talking real money!   I am currently leaning toward the Fridgoboat unit because of their keel cooling unit.  This sounds like the best of both worlds with water cooling and no pump. 


Many of the web sites I have visited suggest an evaporator in the freezer and a holding plate in the refrigerator.  It would be great if I could put my existing holding plate(s) in the frig. and put a DC evaporator in the freezer.  The problems with that is the holding plates are freezer plates designed to freeze at zero F versus refrigerator plates that freeze at around 28F.  Additionally, the system is R12 based and I'm not sure how hard it would be to find someone able to reroute the lines in an R12 system or convert the R12 to something else more environmentally friendly.  Also, the plates do have plugs in them which leads me to believe the eclectic solution could maybe be changed to a refrigerator solution.  All that seems like a lot of work for a 34 year old system.  My guess is that left as it is, it will continue to run, but fool with it and that will be the beginning of the end.  So, maybe I'll just add an evaporator to the freezer and see how things work. 


Anyone out there have any experience converting a Grunert 120 volt AC system?



From Goran on Pepa 2


I am using single water air EZ Kool engine, 2 plates in freezer and spill over fridge on Pepa 2 (317) for 5 years, mostly in Bahamas.

Usually it works OK, but it has difficulties coping when the engine is running. It uses between 120 and 150 AH/ day. The reason for that high consumption is the state of insulation.


I am sure that your work on rebuilding the ice box will pay off big and that once cruising, you will be very happy to have done it.


As I intend to re insulate, I would appreciate your input if it is possible to save and reuse existing inside Fiberglas moulding.


From Richard on Magic Moment


I have 2 Grunert systems aboard Magic Moment, Brewer 44   #304. 

One is 120 volt AC with water cooling pump and also Air cooling when on the hard.  I also have an engine drive pump with 12 volt DC clutch.  I recently had the engine drive pump replaced with a new one.  Come to find out the Grunert pump is made by a truck compressor company and can be purchased at about 1/3 the price.  I also had the 120 volt system serviced.  When all this was done we converted from R12 to R135A.  The new gas is a blend, and much more environmentally friendly I'm told.  The 135A is also easy to find in the USA.  It has all been working very well now for about 4 years.



From Tom on Lone Star


I had the "Versimatic" system, which was powered by a 90v DC Leeson motor (yes 90 v).  There was a 90 volt alternator mounted on the port side of the engine to run the motor.  There was also a rectifier to convert AC input to the 90 volts to run the motor.  The alternator never really achieved 90 volts, so we always ran the genset to drive the plates down.  I eventually replaced the 90 volt motor with a 12 volt motor...You may find that you could do that.  You will have to research motor speeds & (get someone to help) calculate pully size to spin the compressor at the proper speed.  This "sorta" worked for me, but I was always having a problem with the seals on the compressor, so eventually canned the entire system.  Fridgoboat makes a very good system, that is what Frostline in St Marteen carries. 

You are right on track with thinking "ships systems" regarding your reefer change-over...If only it was as simple as changing out the unit!



From Dennis on Sweet Dreams


After listening to all of the advice and comments, I'm leaning towards two Frigoboat units.  The people in the tropics who seem to be happiest with their systems have separate units for the frig/freezer.  Pretty soon its going to be time to stop the research and start the work.  Too bad, this is fun.  I started out not knowing a thing about refrigeration except the principles and now I feel pretty knowledgeable.  I'm sure that will change when I join the real world and start the installation.  I'll just have to remember the Cerveza with ice crystals.



From Bryan on Uhane


Our Cool Blue refrigeration is still working great.  I like having the compressor in the engine room and not having to put another hole in the hull for a water cooled system.  Our big problem with refrigeration is the box itself. Our number one job whenever we get to Cartagena is having it rebuilt.  More (and effective insulation) and maybe making it a little smaller to accept more insulation.  Our holding plate will develop 3/4 inch frost in about a week and a half.  Not good.



From Jens on Indigo

We have hull #192 (Canada-1982).  We replaced the Grunert R12 system in 1993 before leaving the US with a R134a system from Glacier Bay.  We kept the original Grunert plates that were in the freezer and added a new plate to the fridge.  Converting to R134a was pretty simple.  Since the oils used for R134a and R12 are incompatible you must get all the old R12 oil out.  We did this using a bucket, a small submersible bilge pump, tri-sodium phosphate (from a paint store), and some hoses.  We just recirculated the tri-sodium phosphate solution through the plates from the bucket until there was no longer any oil sheen on top of the water in the bucket.  Obviously we changed the water a few times.  Pretty simple.  So converting components that are made of pipe is pretty simple.  I don't think for instance that flushing and converting a compressor would work well.  So the Grunert freezer plates are still going strong with R134a in them.

We used swageloc and flare fittings to assemble the new system.  These are not the best connectors for refrigerant gases but have the advantage of being low tech and make self service of the system possible - at least for me.  I do carry a guage set, vacuum pump, compressor oil, a leak detector and a 20lb cylinder of R134a.  Keep an eye on ebay for great deals on used gear.  While I have had plenty of leaks in the system, none have been from these connections.  Usually it is compressor seals or isolation valve packing or component corrosion.

Assuming that the Grunert plates actually have a eutectic solution in them - I have never been able to verify that - it would be highly corrosive and not a pleasure to deal with. 

Also it is the absence of air which prevents the eutectic solution from corroding through the internal pipes.  So the plates are normally filled, leaving a small air space for expansion, and then evacuated before the plug is installed.  Once the plug is removed, air enters, the vacuum is lost and corrosion of the internal pipes leading to eutectic solution mixing with the refrigerant gas - i.e. a mess - follows shortly thereafter.  This happened to us with Glacier Bay holding plate we bought whose plug was not properly installed leading to failure of the plate and then the compressor.

Do you have reference for a web site suggesting an evaporator in the freezer?


From Bryan on Uhane

We used the new one supplied with the unit.  Their tech guy said mount it vertically on the hull side wall -- it has to sit at an angle because it's too large to sit flush against the wall.  We did that for a while and it was a pain to defrost because there was such a mass of frost built up behind it and hard ice would build up on the top side.  We remounted it horizontally on the engine room side of the freezer and have been much happier with that.


I am not pleased with the spill over system.  We're in the fridge 25 times a day, letting in all of this soggy Panama air that migrates to the freezer and turns into ice on the holding plate.  I'm seriously considering a second unit for the fridge when we rebuild.



From Dennis on Sweet Dreams


Cerveza with ice crystals!  Now that is something I can stay motivated about.  You mention that you insulated enough to cut the size in half.  I haven't yet done the calculations on how much reduction in volume 2, 4 or 6" of insulation will cause so I'm curious about how thick your new insulation is.



From Debi  on Serenity


Another option:
Serenity (hull 110) uses the "Coolblue" system by Technautics (
I added insulation to the inside of the existing boxes to reduce their volume by about half. The compressor is air cooled and installed in the engine room. There is one cold plate in the freezer box and ventilation holes between the two boxes to maintain chill in the fridge box.

The entire system was user installed and has been exceptionally easy to maintain.
For the past 5 years, I have been in very warm locations (Sea of Cortez and Central America). The system uses max 5 amps, typically runs 50% of the time for an average daily usage of less than 90 amps.

I make ice cubes, can keep ice cream frozen and yesterday I pulled out a cerveza and it had ice crystals in it. 




From Bill & Judy on Janus


I replaced my Grunert Versimatic system a few years ago with 2 Danfoss BD50f compressors with water cooling, evaporator coils for the freezer (a plate which wraps around 3 sides) and the refrigerator (a small cooling box which freezes ice cubes), plumbing, and simple electronics. The water pump is a Flowjet Quiet Quad 24 volt model 4405-343 which we run at 5 volts, drawing .4 amps. We only have 1 water pump to control both compressors. The output from the water pump was plumbed to flow into the aft sink drain (rather than going overboard like the old Grunert system). There is a schematic of the electronics and a picture of the system on the new Whitby web site under Photo Gallery/Individual Galleries/Janus Gallery/Refrigeration.

Judy got tired of diving into the freezer. Both the refrigerator and freezer bottoms have been filled in with blue foam boards from Home Depot and a fiberglass shower panel (defective and cheap...from Home Depot).

From Debi on Serenity 

I used 1 inch rigid foam insulation. Comes in a big sheet which you then cut to size. I remember there being several layers (particularly on the bottom of the freezer box on the inboard side because I filled in the incline to get a level bottom overall.)

I glued in the sheets of insulation with 5200 quick dry. Then lined the boxes with white plastic sheets purchased at Tapp plastics and again glued in with 5200. Caulk at all the corners sealed everything in place.

The overall box dimensions (in inches) are something like:

 Horizontal: 12 x 26
 Vertical: 23

 Horizontal: 13.5 x 22.5
 Veertical: 21


From Dennis on Sweet Dreams

It sounds like you have the refrigeration issue licked.  As you probably know from prior postings, the only issue with using the aft sink drain is if the through hull is closed or clogged the sink will over flow into the boat.  This happened to us several times when the bottom needed cleaning and the opening was partially blocked.  We eventually rerouted the drain over the side.  This also allows us the monitor the water flow.



From Jens on Indigo

I have used a holding plates in fridge and freezer cruising full time for 15 years.    I imagine that an evaporator in the freezer would provide a 'better' freezer than holding plates in terms of the user experience with frozen foods.  The primary difference I believe is the difference in the temperature that is controlled.  With an evaporator (I imagine, since I don't own one), the compressor will cycle based on the ambient temperature in the freezer so is a direct control of the actual temperature of the food in the box.  With a holding plate, the unit cycles based on the temperature of the cold plate - i.e. the compressor stops once the holding plate is frozen regardless of the actual temperature of the food.   Also the way the controls cycle on a holding plate is based on the eutectic temp. so if you a have a 10deg plate, you normally will wait until the temp of the plate starts rising a few if not 5-10 deg above the eutectic temp.  The compressor will then run and it will cycle off maybe 10 deg below the eutectic temp.  So even though the plate has a eutectic temp of 10deg the temp of plate and its surrounds may range from 0-20deg, which is quite a range.  At one end of the range ice cream will be well frozen and at the other end it will be soft.  A few days of cycling like this and the ice cream will be dreadful.  Ice, on the other hand will freeze and remain frozen, most foods will be fine as well and after six months pulling out a steak and putting on the bbq will be a wonderful user experience in some isolated tropical location, but it won't be the same steak that was kept in your home fridge for six months.  Freezing large pelagic fish - tuna, marlin etc - for consumption over the next month or so will work well. 

One of the problems with R-134a and holding plates is that the R-134a is much less efficient than R-12 at the low end of freezer ranges.  Since you have to get the gas temp very low - like eutectic temp -10 deg or so - to get enough temp difference to transfer heat out of the eutectic into the refrigerant, the compressor works harder and longer using R-134a than it would under identical conditions using R-12.  This was discussed when we put our system in back in the early 90's but there wasn't a whole of experience with R-134a then - cars were still using R-12.  Most refrigeration people at the time were saying that R-134a was a suitable R-12 replacement for air con and fridge but was totally unsuitable for freezer applications due to the low temps involved.  

Since an evaporator system cycles directly on box temperature, you can set the actual box temperature cold enough to keep ice cream and it will keep that temp +/- just a few degrees.  (It will use as many amps as it needs to do this as well).  When you don't have ice cream you can keep the box a little warmer - something you can't really do with a holding plate since the eutectic temperature is pretty well fixed.  The efficiency advantage of a holding plate system may be diminished for an R-134a based system.  Also 20 years ago the only way there could be enough energy on board to have a reasonable freezer was to burn diesel fuel and using a holding plate was a good match.  Today it is possible to at least consider using wind and solar for a freezer and a evaporator seems to be a better match for these sources.  These factors may have encouraged a migration away from holding plate based freezers to evaporator based ones over the last 20 years..


From Dennis on Sweet Dreams

After I forwarded the evaporator vs. holding plate references I was reading the Coastal Climate Control website which touts the Frigoboat system and they recommend an evaporator instead of holding plates as well.  They sell both evaporators and holding plates so I believe their recommendations should be unbiased.  

Nevertheless, I'm not sure why a holding plate wouldn't work as well as an evaporator and have the advantage of being able to ramp up the "cold storage" capacity by turning off the energy control systems when the engine or genset are running.


From Deb on Free N Clear

Free N Clear has gone through several refrigeration systems, from the original Grunert which was replaced with a Rich Beers' (Fort Lauderdale) designed system with 2 heavy duty SS holdover plates in the freezer.  Rich asked "Hard Ice Cream or Cold Beer?"  Lew answered "Hard Ice Cream", which translated at that time to a 110 volt system.  The spill over was done away with as well as the wall between the refrigerator and freezer and a SS plate was installed (decreased the need to defrost).  The cold from the freezer provided ambient temperature to the refrigerator, with a "computer fan" to keep the temp consistent throughout the refrigerator.  Hard ice cream/cold beer.  New compressor, and through hull water pump.  And generator dependent, twice a day for a minimum of 45 minutes each time.  The generator was the highest maintenance item on the boat, so a move was made...


The latest generation was to a 12 volt system.  We have a Nova Kool with evaporator plate in the refrigerator, and a Frigoboat with evaporator plate in the freezer.  Both are air cooled.  The wall is back between the frig/freezer and 2 layers of 3/4 inch thick foam insulation board with aluminum foil facing on both sides covering the walls and floors, with the fiberglass impregnated plastic shower panel covering it all to seal it up and for ease of cleaning.  Concept is that if one fails the other can be used as a freezer. They both use the same Danfoss compressor.  We are finding that the Nova Kool was cheaper, is more efficient and quieter, although picky about the temp setting.  If we dial the temp down it causes the quick coupler fittings to shrink ever so slightly, but enough to cause a pesky/hard to diagnose R134a leak.  Probably the same thing would happen with the Nova Kool.  The next thing would be to put more permanent connectors in.


The ice cream isn't quite as hard, but the solar panels are running it all!  And the beer is frosty!