Grunert cold plate conversion question.

We are converting our power hog Grunert cold plate freezer over to a Frigoboat keel cooled system. We need to start with evacuating the refrigerant before we begin demo. We will have a pro do that part.

The boat is 2001 and as far as we know the compressor and lineset are original. The question they are asking is what is in the system for refrigerant.

Anyone able to help?

There is an engraved plate on the unit that says, or, at least, there should be.

I think those were designed as R12 units and then switched over to R409A, a lubricant-compatible plug-in replacement, with the change in the law.

Even if originally R12, if ever recharged, could be R409A now.

But, I'm just guessing...check the plate.

Plate was hidden, but found it 404A

Oh, wow. I was totally off. R404A was a replacement for R502. I guess that makes sense. Both are more commercial freezer refrigerants than R12 was.

Good find!

"We are converting our power hog Grunert cold plate freezer over to a Frigoboat keel cooled system."


The most common reason for poor refrigeration is poor insulation., not the method by which the heat is removed from the reefer.


With proper insulation , and correct sized plates many eutetic systems require 2 hours of engine running every 3 or 4 days.

FF said:

"We are converting our power hog Grunert cold plate freezer over to a Frigoboat keel cooled system."


The most common reason for poor refrigeration is poor insulation., not the method by which the heat is removed from the reefer.


With proper insulation , and correct sized plates many eutetic systems require 2 hours of engine running every 3 or 4 days.

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3-4 days depending upon how many times you venture into the box too.

Our Grunert system uses 404A as well. Why do you consider your system a power hog? We much prefer it over the constantly running refrigerator we had on our last boat.

When on the hook we run the generator a couple of hours in the morning and evening. That is more than enough to keep the holding plates frozen. Our boat is all electric, so the generator comes on anyway to prepare food.

Russ,

I seem to remember something on the Selene Owners forum regarding your renovation. We’ve had good luck with our system and I may be adding some more insulation to the inside of ours later this summer. Interested to see how your renovation turns out for future reference.

Cheers

The Grunert system works alright. Insulation seems to be adequate. The compressor is pretty big and placed in a manner that renders a portion of lazerette useless not to mention a 110v water pump and dedicated strainer that can go away.

Also our the freezer is not very large and the cold plates take up a good deal of space.

We are in the process of replacing all of our refrigeration and while we could leave the grunert in place, the conversion is relatively inexpensive, and will give us more freezer space due to much thinner evaporator with less stand off. Also a much smaller and more power efficient compressor that can be placed on top of the freezer freeing up laz space.

We have a planned haul coming up, so minimal cost for the keel cooler install.

Crusty Chief said:

Russ,

I seem to remember something on the Selene Owners forum regarding your renovation. We’ve had good luck with our system and I may be adding some more insulation to the inside of ours later this summer. Interested to see how your renovation turns out for future reference.

Cheers

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Thanks John,
Yes there is another Selene that did this conversion, Maerin I think, seems to be happy with it

Windows are nearly done finally! Lots of electrical projects this winter, just getting started on the refrigeration. Sound like your southern travels are going well!

The basic test to see if a box is insulated well enough for a 12v Danfoss unit can keep it cool is very simple.


Place a large (25lb+) block of ice in the box , let it sit for a day and weigh it .


Wait a day or two and weigh it again.If it looses (melts) under 5lbs per 24 hours , your in luck the insulation is fine. The extra space from the removed eutetic plates is great.


If the ice melt is over 5lb a day re-insulation , or a second unit for the freezer section works , buy you may need a bigger house batt bank.

Has anyone tried the new vacuum panel insulated boxes? Looking for some information.