Cold Plate Conversion

[hmason]

Our Grunert Cold Plate refrigeration system needs to be replaced. It consists of 2 refrigerator cold plates and one freezer cold plate, plus a new compressor/condenser system. Very expensive to do. I'm looking for alternatives to convert to something else that does not entail removing the existing "boxes" as the Grand Banks teak cabinetry is beautiful and also expensive. Thanks in advance for the input.

 

[hmason]

I can't get the picture straight. Sorry.

 

[ofer]

following closely...
I have a similar setup on my DeFever except its side by side. the marine solutions are way expensive. I was wondering if there is a non-marine 110V product that may work.

 

[sean9c]

Why is it being replaced? If the insulation and interiors are still good you could just update the components. I'd think that it'd be pretty straightforward to talk to someone like Sea Frost about compressors and plates and such

 

[SteveK]

This summer I converted my ice box into a freezer with this kit.
you could re & re yours
https://ca.binnacle.com/p5158/Nova-Kool-LT201-F-Ice-Box-Conversion-Kit-3-Plate/product_info.html

 

[DavidM]

I am not a big fan of cold plate marine fridges or freezers. As a reviewer once said and I paraphrase "Batteries are a better and cheaper way of storing energy than a cold plate". Cold plates may have their place when engine driven compressors run them on charter boats. But for your own boat, no.

So I would suggest ripping the whole system out and replacing it with a compressor/condenser and separate evaporator to replace the cold plate. Alder Barbour, Isotherm, Frigoboat, etc. make these packages for something north of $1,000.

I used to have a Frigoboat system which is unique as it has a bronze shoe that attaches to the hull and condenses the freon. Colder raw water is a more efficient condensing medium than air. Also you probably want the variable compressor speed module that senses how much time the compressor is running and slows it down or speeds it up for optimum efficiency.

I don't know of any 120V AC system and if there were it would probably be much less efficient than the 12V Danfoss compressor based systems.

David

 

[Giggitoni]

Our Grunert Cold Plate refrigeration system needs to be replaced. It consists of 2 refrigerator cold plates and one freezer cold plate, plus a new compressor/condenser system. Very expensive to do. I'm looking for alternatives to convert to something else that does not entail removing the existing "boxes" as the Grand Banks teak cabinetry is beautiful and also expensive. Thanks in advance for the input.

We replaced our Grunert system on our 1986 42’ Classic about two years ago with the 12-volt, water-cooled, Frigaboat system. We used the existing GB boxes. So far, we’re very pleased with the decision to make the switch.

 

[HTurner]

We replaced our Grunert system on our 1986 42’ Classic about two years ago with the 12-volt, water-cooled, Frigaboat system. We used the existing GB boxes. So far, we’re very pleased with the decision to make the switch.

You mean Frigoboat -- Frigaboat has a different connotation. I hear great things about their systems.

 

[gsholz]

When we bought our 52 GB Europa, the cold plate system (2 refrigerators, one freezer) was not operational (low charge). But all it required was 4 lb of R404A. Once working we liked the system. The cold plate system charged up much quicker than our batteries. It only took one hour of generator time to freeze the cold plates for the rest of the day. So, unless your compressor is broken I'd look into repairing the system.

 

[FF]

"As a reviewer once said and I paraphrase "Batteries are a better and cheaper way of storing energy than a cold plate".

While that is true there are no 40year old batts still working .

The huge advantage of cold plates is they can be frozen very rapidly , and are silent in operation.

The usual hassle today is marine service is nearly impossible as the current folks have never seen a eutetic system.

Cold plates must be driven 10 to 15deg below their melt temperature to function and most measure cut out temperature by suction, not a thermostat.

Best case would find a commercial store refrigeration guy, to see what , if anything, needs to be repaired, or just serviced.

 

[hmason]

I appreciate all the great input. Tomorrow I will contact the GB yard here in Stuart FL. I’m sure they’ve faced this issue before. I have decided to get the system fixed. I’ll keep you all advised of progress.

 

[DavidM]

FF makes a good point but I think he is talking about AC driven fridge compressors or maybe engine driven. A 12V Danfoss compressor won't freeze it very fast at all. In fact with a 12V Danfoss compressor you are wasting energy freezing the eutectic plate to near zero degrees or so when it would be much more efficient just to cool the fridge to 35 or so.

But if you are going to run your generator or the propulsion engine anyway to freeze the eutectic plate, I agree it is a good choice. I used one in a charter sailboat many years ago. Running the propulsion engine for an hour in the morning and evening to freeze the eutectic plate kept the fridge nice and cold.

David

 

[SteveK]

A very informative read.
Is A Cold Plate System Right For You?

 

[hmason]

The refrigeration service guy told me that the condenser has a seawater leak into the Freon line. From my reading I know this is possible or even probable in a 25 year old unit. So I can see the need to replace the entire compressor condenser unit. It is R-22. What I question is his statement that I need to replace the cold plates as well. There must be a means of evacuating the lines to the plates and to install a dryer as well. Opinions please? Thanks to all.

 

[Choices]

Just did mine and it's posted on our blog, grandbankschoices.

Was about a grand per unit.

My frig can now easily freeze, and the freezer can go to -16 at half thermostat.

Lots of issues with the GB boxes. They are built from the inside out. Can cause you problems if unaware.

I used Vetrifrigo. Took longer to remove than install.

Send me a PM and we can talk on the phone.

One of best mods made to the boat.
Nothing like eating a rock hard fudgesickle while going down the ICW.

 

[Choices]

Also, unit can be ac/dc or both.
Water or air-cooled.
Both mine are where old unit was in lazarette.
So quiet you can't hear it even when next to it.
Ours are air-cooled.
I would not put in ER unless water cooled.
Works so much better than the cold plate system.
No comparison.
Every GB on my dock is changing over.
Went from 90 to 10 in about four hours.
A very easy project.

 

[BigTime]

The refrigeration service guy told me that the condenser has a seawater leak into the Freon line. From my reading I know this is possible or even probable in a 25 year old unit. So I can see the need to replace the entire compressor condenser unit. It is R-22. What I question is his statement that I need to replace the cold plates as well. There must be a means of evacuating the lines to the plates and to install a dryer as well. Opinions please? Thanks to all.

The worst part of our Grunert repairs was not wasting the $2600 patching a 25 year old system but the ruined Bahamas cruises 2 years in a row having a “BROKEN” refrigeration system. Finally installed 2 ) 12vdc/120vac ,air cooled Virtifrigo units for not much more than the “Wasted” repairs. That was 6 years ago and they are working out great !

 

[FF]

To my mind the big downside with a cold plate setup is the system is built into the boat.

That means the insulation selected is there "forever" , and there have been may advances since cork .

Engine drive is great IF the insulation is good.4 to 6 inches works best.

On our 90/90 we have 2 plates, one in the freezer , one in the fridge. Dockside we only operate the freezer and use a gadget that steals cold from the freezer for the fridge section.

Underway, offshore, both plates operate , and we have to remove soft , tomatoes etc to an Igloo to keep them from being frozen.
This choice was made as a big freezer box works well when the food stores are far apart.

In local cruising we get 4 days of frozen in the freezer , so every 3rd day we anchor in a new harbor. 5F deg nice hard ice cream!

Living aboard the 120v freezer circuit is enough to keep the fridge section cold and the boat needs no extra help for a weekend.
Having the 120V circuit allows the use of a cheap inverter to power the small compressor should the engine drive fail underway.

Mike Adler who patented the 2 circuit eutetic system found that the copper coils the refrigerant got ice covered while bringing the plate temperature down.

This slowed down the plate freezing , why it takes an hour .By creating a solid copper insert that had the refrigerant path pressed into the time to freeze was reduced to under 20 min.

Perhaps with more modern mfg techniques all plates could be as easy to freeze.

 

[jgtrucking]

I am not a big fan of cold plate marine fridges or freezers. As a reviewer once said and I paraphrase "Batteries are a better and cheaper way of storing energy than a cold plate". Cold plates may have their place when engine driven compressors run them on charter boats. But for your own boat, no.

So I would suggest ripping the whole system out and replacing it with a compressor/condenser and separate evaporator to replace the cold plate. Alder Barbour, Isotherm, Frigoboat, etc. make these packages for something north of $1,000.

I used to have a Frigoboat system which is unique as it has a bronze shoe that attaches to the hull and condenses the freon. Colder raw water is a more efficient condensing medium than air. Also you probably want the variable compressor speed module that senses how much time the compressor is running and slows it down or speeds it up for optimum efficiency.

I don't know of any 120V AC system and if there were it would probably be much less efficient than the 12V Danfoss compressor based systems.

David

Nothing personal, but I could not disagree more. However, it does depend on usage. In the off-season, I shut by holding plate system down. I still use the boat, but use my fridge/freezer on the dock. In the season when I go out, I use it. The holding plate system holds great overnight. It holds for up to 48 hrs actually. the inverter CAN operate the condensing unit, while underway. SO anywhere I anchor, if I don't need the heat pumps (heat or a/c) I don't need to run the genset. But this system depends on travel. If you are sitting at the dock, or at anchor for days and days at a time, the advantage is gone. If you travel, they are wonderful.


I did some repairs to my R12 version this spring. When the day comes I can't keep it operating, I will take the hit and rebuild with a new version taking modern refrigerant.

 

[dz1drwww]

I converted old Grunert cold plate fridge/freezer system in my GB42 to use CoolBlue compressors about 4 years ago and love it. The CoolBlue system runs off 12V DC, draws hardly any power, has been bullet proof and maintained the original beautiful teak GB doors. Did the work myself so I’d be happy to share my experience if you’d like, just PM me.

No tie to the company, just a very satisfied customer. Here’s their link: http://technauticsinc.com/

 

[gunho1]

I converted old Grunert cold plate fridge/freezer system in my GB42 to use CoolBlue compressors about 4 years ago and love it. The CoolBlue system runs off 12V DC, draws hardly any power, has been bullet proof and maintained the original beautiful teak GB doors. Did the work myself so I’d be happy to share my experience if you’d like, just PM me.

No tie to the company, just a very satisfied customer. Here’s their link: CoolBlue Technautics Marine Refrigeration

Another vote for Cool Blue. We had one on our old boat, ran constantly for 14 years for us and still going strong for the current owners. Rich Boren is great.

 

[dz1drwww]

And yes, Rich, the owner of the company, provides EXCELLENT support……. Watch a few of his YouTube videos and you’ll see what a great resource he is.

 

[ben2go]

Check out Cool Blue. Their systems are very good from what I've heard. Their unit is what I plan to use.

 

[FF]

"Power consumption in a7 cubic foot (200 liters), ,,,R-30 box"

Its that R -30 box insulation that is hard to come by.

Remember most foam kits require unlimited space for expansion , as soon as it is used to fill a compartment , you are lucky to get 1/2 or 1/3 of the advertised R value.

To check how good the insulation is in your box , purchase a block of ice and stick it inside. Do not open the box for 24 hours then weigh the ice, close the door and wait 24 or 48 hours.

Then weight whats left of the block of ice.

IF you melted less than 5 lbs per day electric refrigeration will work.

If you re great with math measure the outside surface area of the refrigerated area , and use the BTU required to melt a pound of ice per hour to figure how many BTU the compartment gains in an hour.

You can then decide how long per day the unit will need to run and how fast it will empty the house battery.

 

[contingensea]

Our Grunert Cold Plate refrigeration system needs to be replaced. It consists of 2 refrigerator cold plates and one freezer cold plate, plus a new compressor/condenser system. Very expensive to do. I'm looking for alternatives to convert to something else that does not entail removing the existing "boxes" as the Grand Banks teak cabinetry is beautiful and also expensive. Thanks in advance for the input.

Have a look at https://www.coastalclimatecontrol.com/
They resell several solutions.

Our 99 GB 42 Europa has Grunert as well. We only have a few months of cruising experience and are finding anything requiring 120 AC and water cooling to be inconvenient.
I’m only in the planning stages but my thinking is to replace the refrigerator with a two drawer unit and the Grunert freezer box, which only gets down to 9 degrees, with a bendable flat plate evaporator. Both will have air cooled dual voltage compressors.

 

[dz1drwww]

….the 120V & fresh water cooling requirements are exactly what drove me to CoolBlue.

 

[FF]

."the 120V & fresh water cooling requirements are exactly what drove me to" CoolBlue.

There would be no need to use water cooling if the compressor package was changed out to air cooled.
These are OTS commercial units , just be sure your inverter can start the compressor.
Or run it off the noisemaker, once a day.

 

[bnoft]

Might be late with this response, we replaced cold plates on our old GB with 2 Sea Frost units; one for frig and one for freezer. Used existing boxes and installed new units in ER where cold plate compressor was located. New system could be water cooled or air cooled, opted to try air cooled and ducted air to units from forward hanging locker. Ours was a Classic GB but I think you could do same. Email me for details. We were very satisfied with Sea Frost, freezer would make ice (in trays) and keep ice cream frozen solid. Could also turn temp control up and use freezer as frig if needed. These performed well in the middle of the summer on the Chesapeake.

 

[Cigatoo]

I converted old Grunert cold plate fridge/freezer system in my GB42 to use CoolBlue compressors about 4 years ago and love it. The CoolBlue system runs off 12V DC, draws hardly any power, has been bullet proof and maintained the original beautiful teak GB doors. Did the work myself so I’d be happy to share my experience if you’d like, just PM me.

No tie to the company, just a very satisfied customer. Here’s their link: CoolBlue Technautics Marine Refrigeration

Interested in hearing your experience. Why not give us all the 5 mile overview on the forum?

 

[dz1drwww]

Sure, I’d be happy to share my work, but I’ll need to explain a little about my specific GB configuration for it to make sense…. In my GB I have the freezer aft the port door and the fridge forward (the port door). I do not have an L configuration on my galley cabinetry. I also wanted to maintain the teak wood doors with the temp gauges that were delivered with the boat when it was new. Essential I wanted the salon to look “stock”.

My fridge/freezer system was completely operable when I started this modification. The main reason I undertook this project was my 3000w true sine wave inverter did not have the surge capacity to “start” the Grunert compressor, therefore, the only way I could “refreeze” or “recover” the cold plates would be on generator or shore power. My system would take more than a few hours of generator run time before the fridge/freezer temps to stay cool enough for me. After running longer voyages the heat from the engine room would cause me to run the generator for longer periods of time than I wanted to run to allow the fridge/freezer temps to recover. Plugging into shore power after voyages wasn’t an issue, but not every voyage of mine ends up in a marina.

I’m going to make the assumption that if you’re about to undertake a conversion you have a knowledge on how the Grunert system is configured with a single compressor and the solenoid valves/tubing to jointly run the system. Converting to a CoolBlue system required two compressors to make the system function. Specifically, one CoolBlue unit for the fridge and one CoolBlue unit for the freezer. In the completed form of my upgrade, the freezer and fridge both run independently now.

CoolBlue sells their systems as a set, meaning the cold plates, the copper line sets and the compressor, all recharged and ready to install, plug and play. Had I had access to all the required areas to install the CoolBlue systems, the two sets of CoolBlue systems would have been an easy install. In my GB’s configuration, cold plate mounting in the fridge is easy, replacing the Grunert compressor with the two CoolBlue compressors is easy, but the supply/return tubing, that’s different. Access to the bottom of the fridge, in the engine room, is not a problem for the tubing runs. However, the freezer is directly above the port fuel tank and there’s only about an inch of space rendering it completely inaccessible.

My solution was to cut the existing tubing below the refrigerator and splice in the new CoolBlue units into each tubing pairs (one pair for the fridge and one pair for the freezer) and leaving everything on the cold box side of both of those splices as original from GB. I didn’t touch anything after the splice, meaning the inaccessible freezer tubing, each temperature controls, each TXV valve, each cold plate…. All I had to do is run new 12V DC wiring from my house bank with the associated breakers, install the two CoolBlue compressors and splice the tubing together (re the sketch). I did have to vacuum down each of the systems after the the configuration was complete, and bring the 134 charge to proper levels.

I did not purchase CoolBlue’s cold plates or copper line sets (I did need to buy an adapter to attach the vacuum pump). I did not remove the cold plates at all.

I really like this system, and it has reduced my boating issues significantly while maintaining that gorgeous stock look.

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