Fridge Option Question?

[Madehn]

i am working on the refrigeration options in my Gulfstar 51 Sailboat-- the current setup has two seperate boxes for fridge and freezer- each has two holding plates approx 16 inches x 14 inches and 3 inches thick. The system is an older crosby unit which is 110 volt water cooled- it still works fine but we are planning on going cruising next year in the Carribean and think we would prefer 12 volt as we have d400 wind genny and almost a kilowatt of solar power to charge batteries. Dimensions of the two boxes are as follows
fridge- 46" lenght x 22" width and 28 inches deep (one holding plate on each end (22" walls)
Freezer- 21" length x 15" width and 21" deep (one holding plate on each side)

both have a seperate thermostat- there is also a seperate icemaker installed but i am not overly concerned with it. I believe it is a seperate system with its own internal compressor etc.
In your opinion what is the best option?
1)leave the old system in place and add in a technautics system on the blank walls of each of the boxes
2) tear out the old system completely and replace?
3) tie into the existing system by adding a 12 volt component ( not sure this is feasible)?
4) take out everything but the holding plates and reuse them?
5) something else that makes more sense to someone with more expertise than i have
Thanks in advance for informed opinions!

[Typhoon]

Good morning Madehn.

This is the exact project we do and why I got into the business.
First of all are your boxes side by side , and do they share a common wall .

Next thing your Gulfstar is over 30 years old and unless the insulation has been redone you can be sure that it is not performing , ie , water soaked , or falling apart . If you have any hope at all of running your refrigeration system in the tropics with hope of using solar only this will need to be addressed .

We help our customers through this process with support at every step of the way .

With good insulation you have got the heavy pulling done and refrigeration nirvana is close at hand .

Regards John
www.coldeh.com

[Richard Kollmann]

Madehn, Before answering your question it is important to understand what the energy consumption of the system is presently. Do you know the size of compressor you have? What is the amperage draw of the system? In a Texas summer how many hours a day does compressor run now?
With the above question answered and the information already given you should be able to get some good guidance.

[Madehn]

i will check that out this weekend and get you some numbers-- no the boxes do not share a common wall. when we brought the boat from Fla to Tx in the summer the boxes held ice extremely well but we were careful about keeping lids shut etc.

[OzePete]

For your refrigeration project may I suggest..

1) As John indicates the first thing is to check your cabinet’s insulation. There is no bullet proof way to do this but a good indication is this... Run both cabinets down as cold as possible and hold at this low temp for a few hours. Then check the outsides and under the cabinet where possible both visually and by feel to see if there is any abnormal external coldness or cold patches. (Sweating or extra cold feeling) If there is then the insulation needs replacing as a priority.

2) If the cabinet is fine, discard all existing refrigeration equipment and install new correctly engineered component packages, matched to each cabinet’s requirements. (We don't recommend re-using existing eutectic plates as the evaporator tubing in them is most likely 1/2" and, unless re-piped, will cause oil retention thus starving the compressor. And adding 12VDC systems to existing equipment may work but usually not for long!)

3) Freezer: As Richard suggested, establish each cabinet’s heat load so that capable equipment can be selected. (Pic 1.)
I have applied both of your cabinet details to our estimator and the freezer is easy being 103 Litres and can be serviced via a Secop BD50 (2.5cc) or BD80 (3.00) compressor system or as in the estimate below, with the larger capacity Ozefridge BE90 (3.5cc) and best air / water cooled for the tropics.

4) Fridge: Establish the fridge cabinet heat load so that capable equipment can be selected. (Pic 2) I have applied this cabinet's details also and note that at 442 litres a Secop BD80 (3.00) system will do the job but struggle therefore suggest the larger capacity Ozefridge BE90 (3.5cc) and essential with air / water cooled for the tropics.

5) Next select suitable equipment and install.

Click on image to expand...




Please note that while I was able to convert your cabinet dimensions to mm, I had to estimate you insulation thickness as 100mm (4”) Estimates are for extreme conditions.

Estimate cost of complete system packages for both cabinets US$4800 total.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[Richard Kollmann]

Originally Posted by Madehn

i am working on the refrigeration options in my Gulfstar 51 Sailboat-- the current setup has two seperate boxes for fridge and freezer- each has two holding plates approx 16 inches x 14 inches and 3 inches thick. The system is an older crosby unit which is 110 volt water cooled- it still works fine but we are planning on going cruising next year in the Carribean and think we would prefer 12 volt as we have d400 wind genny and almost a kilowatt of solar power to charge batteries. Dimensions of the two boxes are as follows
fridge- 46" lenght x 22" width and 28 inches deep (one holding plate on each end (22" walls)
Freezer- 21" length x 15" width and 21" deep (one holding plate on each side)

both have a seperate thermostat- there is also a seperate icemaker installed but i am not overly concerned with it. I believe it is a seperate system with its own internal compressor etc.
In your opinion what is the best option?
1)leave the old system in place and add in a technautics system on the blank walls of each of the boxes
2) tear out the old system completely and replace?
3) tie into the existing system by adding a 12 volt component ( not sure this is feasible)?
4) take out everything but the holding plates and reuse them?
5) something else that makes more sense to someone with more expertise than i have
Thanks in advance for informed opinions!

Usually 46 foot and larger sailboats are equipped with onboard generators and industrial type refrigeration not 12 volt refrigeration. These large sailboats almost always have on board air conditioning to prevent mildew by dehumidifying interior air and to provide creature comfort in hot weather conditions. The Gulfstar 51 regardless of the model will be equipped much the same as other boats of this size. Because these boats have accommodations for eight or more people this is why refrigerator box is so large in this boat, 16.4 cubic feet. The freezer is 3.8 cu ft. The two refrigerator holding plates are sized for only a ten cu ft box which means compressor most run more than twice a day. The freezer plates are sized correctly for a box of five cu ft.

The main concern with refrigeration in boats especially older boats is the insulation’s resistance to conduct unwanted heat. Even closed cell insulation over time can outgas the insulating gas stored in each cell allowing moist air to inter these cells. There are ways to determine if insulation is still expectable for the cooling energy available.

This boat currently has an operating refrigeration system that can answer the open question about is there enough insulation or is more refrigeration capacity requires. By reporting present compressor current draw and hours of compressor running time in a 24 hour day and adjusted for any changes in planed cruising climate temperatures, many questions can be answered.

Additional questions asked by owner:

In your opinion what is the best option?
1)leave the old system in place and add in a technautics system on the blank walls of each of the boxes?
My answer-- Yes, your boat’s single refrigeration system does need redundancy for a year cruising in the Caribbean. An Cold Eh Marine designed system especially designed by John without wasting space of an additional eutectic plate is a good 12 volt solution for freezer. The 16 cu ft refrigerator box’s heat load in the tropics or even in Texas is too large for any of the small 12 volt refrigeration units. Grunert refrigeration has ½ HP 12 volt units that would solve your problem for the refrigerator cooling capacity. John at Cold Eh Marine also has a twin 12 volt Danfoss condensing unit that could supplement the old Crosby and also provide redundancy.

2) tear out the old system completely and replace?
My answer—When I do a worst case projection of Btu of cooling required in the tropics for both boxes you need 11,280 Btu of cooling per day. It would be difficult to remove present system and find a equal or better system that is presently designed for your application.

3) tie into the existing system by adding a 12 volt component ( not sure this is feasible)?
My answer— I would need to see a picture of existing holding plates. Crosby 30 years ago used Dole eutectic plates with duel evaporator coils inside. This design of a plate makes it possible to connect another condensing unit to all plates without disturbing present system.

4) take out everything but the holding plates and reuse them?
MY answer—Yes it is possible but I an not in favor of it unless plates are reconditions correctly and new condensing unit’s refrigerant flow corresponds to plates evaporator coil size insuring adequate oil return to compressor.