CoolBlue - is it worth the extra $$$

[Richard Kollmann]

What I am trying to say is normalized desirable box temperatures result from a simple understanding of heat transfer. If you like the equipment you have and are satisfied with your box temperatures as they are that is all that counts. Another point, ignore comments on spillover divider material if it does not provide a non conductive heat value of at least R 20. There must also be a means of adjusting divider heat transfer as ambient temperatures change.

Mechanically tumbling air with a small fan in my tests produced a 6 degree F box temperature reduction throughout box.

Most all technical books especially on boat refrigeration are out of date technically after four years. For my books updated revisions go to my free web site and forum. For revisions to refrigerator performance enhancements with fans see section on FANS.

[exMaggieDrum]

My experiences pretty much agree with what Richard K has stated in the above two (and previous) posts. And with Rich B too. My old Whitby 42 had an enormous fridge. I took everything apart and put in an additional 2 inches of pink insulation material (the best I could get at the time that I thought would be durable and relatively inexpensive). Since the box was already so big I could spare the reduction in size. I took out the drain, improved the door seals, etc. etc.

And then I put in my Cool Blue holding plate system and junked the troublesome, high maintenance, old DC and engine driven systems that were on the boat when I bought it. It would keep steaks and ice cream frozen across the South Pacific for months at a time. The only loss we had was from the food inspection nazis at some countries we checked in to. The only problem I had was from me not properly tightening one of the connectors.

The holding plate was big enough that it went from the bottom to the top of the freezer so that some plate was always exposed. It was also stood off from the back so that there was at least some air flow on the back. There was a small DC fan to help and it had two openings on the spillover plate. I fine-tuned the spillover with 2" pieces of styrofoam to close or open the top plate as required. The items in the refrigerator side were on shelves and in baskets with holes in all sides.

The freezer was pretty much just packed with stuff without much airflow but it still kept everything cold (to about 0 to -5 degrees F). The Cool Blue system worked flawlessly and I would buy a newer version (from what I know today) in a heart beat. I don't have a lot of experience with my current setup so I may replace it with a Cool Blue too. But first I already know it is not insulated well enough.

The single best thing IMHO is to improve the refrigerator/freezer box first and then put in the system of your choice. If your box isn't up to snuff you will not be happy with whichever system you go with (or you will be using far more electrons than needed which you may or may not be able to afford).

[SV THIRD DAY]

Originally Posted by missourisailor

Rich,
Let for now assume that we have determined that a second holding plate would be of help.

Would there be any advantage to installing them as "shelves" as opposed to mounting them on the wall/s?

My thought is that it would help because all six sides would be able to absorb heat in the shelf configuration. On a wall mount only 5 sides would be exposed. With one of the larger square surfaces smack up against the wall and only able to soak up heat from the wall.

I would think that even if you mount it/them on stand-offs away from the wall, it would be better than right up against it (as mine is now)

What are your thoughts?

Absolutely there would be an advantage. The reality is that the "air gap" between the holding plate (or thin rolled evaporator) and the wall becomes filled with frost and ice since you really can't access it regularly to scrape it off with a spatula like you can the front and sides of the plate. Unlike a thin rolled evaporator, you simply are not going to punch a hole in the SS holding plate, so we recommend aggressive frost scraping frequently with a SS spatula to keep your frost from building up to over 1/4 thick and then eventually turning to ice.

So if you are able to mount your holding plate in a way that essentially makes the two large sizes available for more frequent de-icings and make that surface area available to more efficient heat transfer...bingo...you win.

But What do you win?
You will get lower box temps from the increased heat transfer, so that is a good thing of course.

Now for the money question that you seem to be after:
Will you get a lower compressor cycle on times OR a total decrease in daily power usage?
No.
So then why go through the hassle of mounting the holding plate (all 25lbs of it) suspended in the box as a shelf if getting a lower daily power usage and better compressor cycling is what you are after?

We seem to be dancing around the issue here so lets hit it head on:
If you already have the most energy efficient refrigeration system, but are still using more power and have more compressor "on time" than you are happy with, how do you address that?

1.
Let's make sure that the system you have is tuned correctly (Charge, TXV, and compressor Health).
2. Add insulation to improve the R-value and shrink the box volume.

You can't beat the laws of Physics and if your Box volume and insulation R-value is letting in an amount of heat into the Box that requires the compressor (from any manufacturer or brand) to run continually to pull it out. Then the unit is simply undersized for that box and fine tune tweaking around the corners isn't going to fix that.

Adding the second holding plate if you have excess power available when the solar is pumping out amps or when motoring can help reduce the overall power usage by means of storing energy in the places. It will also give you lower box temps...but what it won't do is make up for either a Box too large for the compressor to handle or for poor insulation. I don't want to sell someone a $900 holding plate for them to plumb in series to the one they already have and them not be happy with it because they were expecting things it was not going to be able to accomplish.

[SV THIRD DAY]

Originally Posted by Quote

Ignore comments on spillover divider material if it does not provide a non conductive heat value of at least R 20. There must also be a means of adjusting divider heat transfer as ambient temperatures change.

I have to disagree with this comment simply due to having thousands of installed systems and two test boxes currently running at the office. We recommended and use in our test boxes a 1" rigid foam (polyiso) divider between the Freezer and Refrigerator box sections with a 2" hole 1" up from the bottom with an adjustable flapper valve. For the top, leaving a 1" gap works nice and easy.

A 1" piece of PolyIso has an R-value of 6.5 a long way from R20 and it works great. That has been our standard recommendation on literally thousands of spill over systems that are able to control and maintain the temperature differential between the Freezer and Refrigerator Boxes.

I've never seen a 3"-4" thermal divider between a refrigerator and freezer boxes in a spill-over set-up and that's what it would need to be to get close to an R20 with the standard rigid insulation boards. Maybe that was just a typo, but it's also how cruise rumors get started, so I just wanted to correct it.

[Richard Kollmann]

Rich you should check with randy more he will tell you to compare your ideas against the new standards within the refrigerator design industry. Randy's concept of the Coolblue machine was a leader when it was the only unit that truly took advantage of Danfoss BD 35 variable speed compressor's exceptional SCOP performance for small refrigerated boxes in very warm climates.

[missourisailor]

Originally Posted by Richard Kollmann

Rich you should check with randy more he will tell you to compare your ideas against the new standards within the refrigerator design industry. Randy's concept of the Coolblue machine was a leader when it was the only unit that truly took advantage of Danfoss BD 35 variable speed compressor's exceptional SCOP performance for small refrigerated boxes in very warm climates.

Richard K,

I'm a bit at a loss here.
Previously in this thread and others, you elude to your thoughts about holding plates not being efficient as thin plates. Then you made some comments that if Cool Blue still used Danfoss compressors, they would still be your top choice.
On your web site and fourm, you don't even mention thin plates and tout holding plates as king. Although it seems that they havn't been updated since July 2015.

Now with this last post, you are hinting that Randy is having different thoughts, and rethinking the whole holding theory.

So what is it?
Are you for or against holding plates on a typical weekender and/or cruiser?

[SV THIRD DAY]

Originally Posted by missourisailor

Now with this last post, you are hinting that Randy is having different thoughts, and rethinking the whole holding theory.

I sense you already knew the answer when you asked the question, but for the record, Randy hasn't rethought his theory and design on holding plates. I could be wrong of course, but I believe the comment was just a little gibe for the Patawan to go back for more training from the Jedi Master after I disagreed with Richard in the prior post about the needed thickness of the thermal divider.

[[For those that don't know, Randy Simpkins was the founder of Technautics back in 1968 and he took me in as a partner to continue the business. Randy trained me in how to build and service the CoolBlue units and still works with us when needed or when his wife wants him out of the house! With his graduate work and research at JPL in thermodynamics, there is no doubt that Randy plays the Jedi Master roll to mine, that's for sure.]]

[john61ct]

Originally Posted by newhaul

calculated it to use about 30 to 35 ah to maintain

Is that per 24 hours?

[newhaul]

Originally Posted by john61ct

Is that per 24 hours?

Yes that is per 24hour period. And with 75 to 80 f ambiant air temperature.

[exMaggieDrum]

Just me but I would always want a holding plate. They take up a lot of valuable real estate but do a better job in what I have seen with my boat and lots of others. And Randy is top notch. I bought my Cool Blue from him at a boat show and he was great. The customer support after was exceptional. I can't speak to the new owners but if Randy is involved it at least should be better than average. Our Cool Blue was a performer and no problems other than an installation (me) error that caused a small leak of refrigerant. After that it just worked and kept on working. We kept ice cream and steaks in the frozen section.

The single most important thing is insulation though. That beats, hands down, any other improvement you can make.

[Typhoon]

[QUOTE
The single most important thing is insulation though. That beats, hands down, any other improvement you can make.[/QUOTE]

Agreed , even the most efficient system in world can not cool the great outdoors on a hot day , the better you can keep the heat out of your box, the better the performance of whatever system you install will be . Then all you have to worry about is reliability and maintenance.

Regards John

[SV THIRD DAY]

A good rule of thumb is that if you Double your R-Value (or roughly thickness of the insulation) then you will Half your power usage.