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**bstreep** · 21-08-2019, 18:17

We have a Grunert Passagemaker 475. Water cooled. It was rebuilt about 8 years ago. We have 2 holding plates, one in the fridge, one in the freezer. We have a continuing slow leak that is either at one of the valves, in the heat exchanger loop, or both. We'd need to remove the unit to fix either of those, and I'm just not inclined to dump more money into a 29 year old unit.

So, we are looking for recommendations. NOTE: We have no solar, no wind. We have a boat that requires running the generator for 1/2-1 hour, twice a day. We are cool with that, and we have zero interest in putting 800 lbs of batteries on our boat. We want a 110v system. Water cooled. We are in Texas, and shoot we run the A/C most of the time anyway. It just works for us.

Pitchondesign · 22-08-2019, 07:18

We have three Grunert refigeration units. These are the most bullet proof refrigeration units you can find and the 475, we have two, are powerful. It wasn't clear whether you leak is cooling water or refrigerant. If the leak is in the heat exchanger coil, whether refrigerant or raw water, replace the 475 as there will be more leaks over time. If its valves, replace the valves. Its way easier and less expensive to replace the 475 with another 475 than fit a different system. Our units are 20 years old and running fine. It took time to get the txv and refreigerant levels correctly set, but once this was done, they have been trouble free.

Coolerking · 22-08-2019, 07:19

Our company builds entire refrigeration systems, refrigerators and freezers, cold plates, and complete air/water cooled condensing units.
Unfortunately we are in Southern California.
Have you had a reputable marine hvac tech come with an electronic leak detector?

I would absolutely pay for a one time service call to find exactly where it is leaking, then decide the next move.

Glacier Marine Refrigeration & Air Conditioning.

**bstreep** · 22-08-2019, 08:36

We have a refrigerant leak. Frankly, I avoid Dometic products if I can. I'd rather trash the whole thing than to use another Grunnert/Dometic product.

Coolerking, pretty funny, I found your information about 10 minutes before looking at your response. I'm pretty good with HVAC and refrigeration, I installed our 2 16K BTU split A/C systems, and I'm EPA licensed (yes, I know it's a BS license). I've run both soap (Big Blu) and electronic leak detectors over the entire system. Every joint, every fitting. The only leak I've found is at the high pressure valve, and it seated all of the way in. It is a very small leak. This makes me suspect the heat exchanger loop. It's only about 6-7 years old, and I should have replaced the entire unit back then. But it leaks down a lot in just a few weeks, and it's gotten worse.

I DO have a good friend who is a tech, and he highly recommends against putting another Grunnert system in. I'm toying with a complete replacement. The holding plates appear good, no leaks of fluid or refrigerant, but I am tired of dealing with it.

Richard Kollmann · 22-08-2019, 14:03

You have an exceptionally good ¾ HP AC refrigeration that is far more practical than a 12 volt unit so the smart decision is to stay with that type system. The question now is to repair, up grade or replace. It is unlikely any other manufacturers unit could better match the system design you presently have. If your Grunert has their Stainless Steel plates with the name GRUNERT embossed in raised letters 4 times on the face they may be the only true eutectic plates currently being manufactured. Based on your 3 hours refrigeration running time daily in a tropical climate any replacement unit will need to produce nearly 10,000 Btu in 3 hours running time to be a direct replacement.

To solve your boat refrigeration troubles there are few options available to you:
1. Remove and replace complete system including Eutectic Holding Plates, electronics and water pump at an estimated cost installed of $8,000.
2. Remove the complete system and install a less expensive unit ¾ to one HP AC unit from one of the three or four other manufactures like SeaFrost.
3. Unless the plan is to replace the entire system the refrigerant leak needs to be located before proceeding to another option. Grunert used standard off the shelf components and only line cast heavy brass line leak proof lifetime flare nuts. When it is reported that a water cooled refrigeration system has a refrigerant leak the first two questions asked are how fast does it leak? And did you test inside seawater condenser for a leak. Other questions relate to a possible refrigerant leak inside eutectic holding plates would be is original fill plug seal still secure? If the fill plug seal is good and there is a refrigerant leak inside plate its shape will be distorted. To test the seawater condenser for internal refrigerant leaks remove both water hoses and replace them with ordinary balloons. Make sure system has at least 50 psi of refrigerant pressure and let stand overnight to see if balloons start to inflate. Refrigerant leaks that take less than a week to affect performance can easily be located with an electronic leak detector or a mixture of soap and water. Very slow leaks of loss over the year can be found by a skilled tech. If all else fails Florissant dye and black light used by auto mechanics can be used but never use over ¼ once of dye in this size system.,
4. Once the leak area is located outside the refrigerated box a complete condensing unit can be purchased from Grunert and installed and serviced locally. After 29 years I would be concerned about electrolysis inside seawater condenser especially with an onboard generator running a high percentage of the time. Estamated cost to replace only the complete compressor condenser platform $3,500.
5. Find the leak and fix it. Remove seawater hoses from condenser and visually inspect ends of water tubes for evidence of loss of metal. It would be interesting to know what the upgrade was 8 years ago consisted of .

**bstreep** · 22-08-2019, 17:27

Richard,

Thanks for the excellent response.

Work done about 8 years ago was compressor replacement, and the seawater condensing line (. Obviously, drier was replaced.

System will hold freon for 2-3 weeks max. Then I have to recharge. There is a sloooow leak at the high pressure valve, and to fix it, it would have to be replaced, which would require pulling the unit.

The holding plates are 29 years old, stainless. No signs of leaks or bulging. When we run it, the freezer is -10 to -15C and the fridge is -5 to 0. That's at the holding plates. When the system was installed, for whatever reason, the top end of the holding plates penetrates the top of the box. It's always been a battle to keep cold air in the boxes, and the fittings on the end of the plates freezes and melts continuously. We've covered it up and it works ok, but it's not right.

While I appreciate your opinions on this unit, we've lived with it for 12 years, and we hate it. It's been a constant maintenance item, the cold plate installation required us to fix rotted counters and wet foam insulation. AND it's an electricity hog. We put a timer on it, so it runs 2 x per day, for an hour, otherwise it just runs, especially when the holding plates are iced up. Over the years, we've spent probably $8-10K on it, and it's still not right. Since we've (and our insurance company) have spent about $250K on this boat in the last 2 years (Hurricane Harvey), frankly, I'm tired of it not working right. She wants cold beer, and I want to quit screwing with it. I hate it.

Thanks for the balloon tip. I'll try that this weekend. I checked with a friend in the business, and he says the replacement Grunnert unit is about $5K right now.

Richard Kollmann · 23-08-2019, 03:59

I have to admit the marine boat refrigeration products are not always up to the task we expect of them.

I do not know what size boxes you have but the energy require by your refrigeration at that latitude could be normal. An academic point about those holding plates they are true eutectic brine plates where other companies plates are less efficient using food grade Glycol antifreeze. The freeze eutectic point of your plates can be identified by the number of notches cut in mounting plate flange behind the line fittings.

I normally believe internal seawater condenser leak failures show up as a very small leak and and progress slowly over time. So if refrigerant is added at 6 months and latter 3 months condenser needs to be replaced before seawater mixes with refrigerant destroying compressor.

If this were my unit I would run it closing the king valve on receiver to store refrigerant in it and close both line valves on compressor condensing unit skid allowing you to remove the skid assembly. A refrigeration shop then can pressurize it with nitrogen and leak check and repaired.

Coolerking · 23-08-2019, 07:13

We build true eutectic plates.
From +25f to -15.

We also mfg custom stainless evaporative blowers for larger boats.

We also provide them to other companies that brand them as their own.
Our equipment is nearly bulletproof, has been installed in many vessels from 30 foot sailboats to 200 foot super yachts.

I have systems that I installed 15 years ago running like new all over the world.

In fact a great customer of mine just loaded my freezer with fresh Alaskan Halibut and Sockeye Salmon.
One of the best perks.

Richard Kollmann · 23-08-2019, 07:32

Quote:

Originally Posted by Coolerking

We build true eutectic plates.
From +25f to -15.

We also mfg custom stainless evaporative blowers for larger boats.

We also provide them to other companies that brand them as their own.
Our equipment is nearly bulletproof, has been installed in many vessels from 30 foot sailboats to 200 foot super yachts.

I have systems that I installed 15 years ago running like new all over the world.

In fact a great customer of mine just loaded my freezer with fresh Alaskan Halibut and Sockeye Salmon.
One of the best perks.

So you do not use Glycols or gels in your plates.