Who provides the best 12 volt refrigeration systems?

[john61ct]

The only reason I could see for not going TXV, would be if it was not the standard choice of my my preferred vendor.

Support trumps overrides technology.

Both ColdEh and Rich's CoolBlue use them.

[a64pilot]

That would be in my opinion an excellent reason

[daletournier]

Originally Posted by newhaul

that is correct .
My only decision would be cap tube or txv. For my holding plate system

It dosent matter ,they both work well. I think we get bogged down here on technicalities. Whether you purchase an ozefridge or one of Rich's systems you'll be happy, they both have thousands of happy customers.

I like Ozefridge (although i currently dont have one ) because Pete and team provided great service, a good price and the unit looks good giving me more placement options BUT im sure Richs Cool Blue would work for me just as well.

40,000+nm's and 9 years my experience is, a fridge from a reputable supplier once installed just keeps going , giving you cold stuff everyday and rarely any problems ever.

[skenn_ie]

Originally Posted by john61ct

I would not know where to start figuring out how to implement that. Suggest any 101 howto's, sourcing links, books to read?

These are pretty bulletproof ​ https://www.bluesea.com/products/762..._-_12V_DC_500A

A few years ago, I was asked lo look at such a system in a fancy 15-month old "toy" boat. Having spent nearly an hour getting access to the engines, I found that one of the relays had stuck closed, but with a high resistance. While in the engine compartment, I noticed that one of the Volvo Pentas had leaked most of it's oil into the pan. At that point, I walked away. IMO, Oil, water and seawater strainer should be checked before every trip. The owner had never checked anything, just called a mechanic if anything seemed wrong.

[longjonsilver]

So let me get this straight about eutectic holding plates. The trick is to get the phase change at the temperature that you desire the refer/freezer to be. Now i see that mixtures of ethylene glycol and water freeze at different temperatures.



And from this chart we see that 32.5% glycol gives us the standard freezer temperature of 0F -18C. Now if we want a warmer freezer - like Richard Kollmann describes on his website say 10F -12C, we can reduce the glycol to 25%, or 17% for an even warmer freezer of 20F -7C as he describes on his website. Anybody know if my figures are correct? Does this take into account hysteresis?

OK great for freezers, but how do we get a eutectic mixture that freezes at 3C 37F for refers? Anybody know?

i believe in self-reliance not only in cruising but in all matters of life. It is empowering to be able to repair and install stuff yourself, so i am trying to learn about this for my boat. i bot a Seafrost DC5000 compressor and a holding plate and need to understand if it is properly sized for my uses, so my research continues.

Richard Kollmann's website has a lot of good tools available for those of us who are DIYers.

jon

[rgleason]

Ours is a Domestic Water and air cooled condenser from Ozifridge. The exchanger has a water channel as well as air fins and fan. We turn the small h20 pump on when it is hot out and often run it when the engine is on to improve cooling and drawdown. When outdoor air is cooler than about 80, just using the air cooling fan is more efficient.

[rgleason]

For refridge, not freezers, we focused on -5 to -6c with shutoff at -7c. It is so long ago we made the solution, testing in the home refridge/freezer, but I think we were aiming a bit higher to -3 to -4c. Reason being it is needed for various btu losses.

[Richard Kollmann]

Originally Posted by longjonsilver

So let me get this straight about eutectic holding plates. The trick is to get the phase change at the temperature that you desire the refer/freezer to be. Now i see that mixtures of ethylene glycol and water freeze at different temperatures.



And from this chart we see that 32.5% glycol gives us the standard freezer temperature of 0F -18C. Now if we want a warmer freezer - like Richard Kollmann describes on his website say 10F -12C, we can reduce the glycol to 25%, or 17% for an even warmer freezer of 20F -7C as he describes on his website. Anybody know if my figures are correct? Does this take into account hysteresis?

OK great for freezers, but how do we get a eutectic mixture that freezes at 3C 37F for refers? Anybody know?

i believe in self-reliance not only in cruising but in all matters of life. It is empowering to be able to repair and install stuff yourself, so i am trying to learn about this for my boat. i bot a Seafrost DC5000 compressor and a holding plate and need to understand if it is properly sized for my uses, so my research continues.

Richard Kollmann's website has a lot of good tools available for those of us who are DIYers.

jon

I hope I never recommended Eythlene Gycol in eutectic plates as three ounces is death if injected. Everyone who manufacturers eutectic plates knows there will be a leakier sometime especially when plate is bolted together just ask SeaFrost.
Food Grade Propylene Glycol I recommended for these plates. I purchased it in 50 gallon drums but in my book I recommended potable water antifreeze sold at marine stores so the percentages are different than pure gycol.

[skenn_ie]

Originally Posted by longjonsilver

i believe in self-reliance not only in cruising

jon

Self reliance is good, especially in long distance cruising. I would like to have a decent(small) lathe and milling machine, as well as being to weld COMPETENTLY. Not many have the space for all that though. I can join 2 bits of steel, but wouldn't like to rely on the joint ! I like to understand the principles, as well as the conventional way of doing things. Convention is just a guide though ;-)

[longjonsilver]

Originally Posted by Richard Kollmann

I hope I never recommended Eythlene Gycol in eutectic plates as three ounces is death if injected. Everyone who manufacturers eutectic plates knows there will be a leakier sometime especially when plate is bolted together just ask SeaFrost.
Food Grade Propylene Glycol I recommended for these plates. I purchased it in 50 gallon drums but in my book I recommended potable water antifreeze sold at marine stores so the percentages are different than pure gycol.

No, Richard, i didn't get it from your website, i forgot where i read about ethylene glycol as opposed to propylene glycol, but here is the ratios for freezing of propylene glycol mixtures.



jon

[john61ct]

How about the potable water antifreeze?

Source links?

And if converting say a freezer box to a fridge, whose holding plates allow the user to swap out the solution themselves?

Should the phase change point really be right at the desired setpoint, center of the hysteresis range, or at the top, or just below?

[longjonsilver]

Originally Posted by john61ct

And if converting say a freezer box to a fridge, whose holding plates allow the user to swap out the solution themselves?

Should the phase change point really be right at the desired setpoint, center of the hysteresis range, or at the top, or just below?

i don't know if this is what you were asking or not:

https://www.amazon.com/Propylene-Gly...opylene+glycol

That's why i researched this - DIY changing the setpoint of the phase change in the holding plates, and i have exactly the same questions as you - where should the setpoint be "set" in the range? It seems to me that this whole subject should be far more straightforward than it is often made out to be, and can be accomplished by the skilled DIYer. The insulation of the box is the greatest unknown, and possibly the most important.

Maybe some others will chime in here to enlighten us.

jon

[newhaul]

Originally Posted by longjonsilver

i don't know if this is what you were asking or not:

https://www.amazon.com/Propylene-Gly...opylene+glycol

That's why i researched this - DIY changing the setpoint of the phase change in the holding plates, and i have exactly the same questions as you - where should the setpoint be "set" in the range? It seems to me that this whole subject should be far more straightforward than it is often made out to be, and can be accomplished by the skilled DIYer. The insulation of the box is the greatest unknown, and possibly the most important.

Maybe some others will chime in here to enlighten us.

jon

if iirc the mix is set for about 10 degrees below the desired stepping of the box.
I am waiting for the exact answer sent a pm.

[Singularity]

Originally Posted by daletournier

40,000+nm's and 9 years my experience is, a fridge from a reputable supplier once installed just keeps going , giving you cold stuff everyday and rarely any problems ever.

A question, for the sake of discussion.

Assuming 40,000nm ago you needed a refrigeration system installed. Assume you had a cold box, but it probably at minimum needed a little insulation, or maybe a complete rebuild (seriously, only a day or two project that will take a week for box work). Also 40,000nm ago assume that you had a 400ah 12 lead or AGM battery bank, maybe a cheap pure sine inverter on board, maybe not.

So, if 40,000nm miles ago instead of having a 12v marine refrigeration system installed (which you did), the question I have is: If you could have had a 400ah LFP bank installed with a commercial off the shelf (COTS) 110-240v AC refer for the same price as the 12v marine refer, would you still have kept your lead/AGM batteries, still gone with the 12v marine refer system? You would have been happy to forego the utility that the LFP could provide in favor of the DC refer reliability given the other options?

In fact I planned on a 12v system, but after I got the LFP, it just doesn't make sense to plop down $1500-$3000+ for a DC system when I can use $200-$400 terrestrial COTS 110-240v refer units. If worried about reliability, I can buy 2-3 extra AC voltage refers for <$1,000, stuff them with boat spares, then seal and stack them in the lazarette until the unit(s) in the cabin fail after 2weeks or 9 years, whichever comes first.

Just my thinking.

[SV THIRD DAY]

Originally Posted by newhaul

if iirc the mix is set for about 10 degrees below the desired stepping of the box.
I am waiting for the exact answer sent a pm.

Correct....
Just like the evaporator temp is always colder than the Box temp....the Holding plate temp is always colder than the Box temp. How much colder...well friends that really depends on your box. But over the last 50 years of Technautics building holding plate systems we learned over the years that a good average number is 10 Degs. That is why our Freezer plate Eutectic mixture Freezes at 0-degs F and our refrigerator freezes at 25-degs F. Notice I'm not quoting % strengths of the Eutectic solutions...why...because different ones have different freezing point t0 % concentration rations and people tend to get a % concentration stuck in their head which is Meaningless if you don't know the specific Eutectic solution being talked about and it's freezing point. That's how BS Dock Rumors and Myths are created with 1/2 the story.

If you have better than average insulation OR if you have a better than average ratio between plate surface area and box volume then you will have less of a delta between box temp and plate temp.