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Old 11-10-2011, 20:55   #1
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New Refrigeration System Plan

Read all the books, articles and tests and this is what I have come up with.

1. System design

Total box 7.5-8 cu ft, spillover system with
1.5 freezer
6 - 6.5 refrigerator
Top loading
min 4" Dow blue board insulation, 6" around the freezer
Frigoboat Capri 35F compressor
200F evaporator
Guardian thermostat and compressor speed control

2. System usage profile

Full time liveaboard.
Worst case scenario, 4 on board, spring or fall in the tropics.
Power: wind gen, solar panels, Honda 2000 gennie, 100 amp alternator with smart regulator, 600 amp hours of battery.

Estimate 6000 - 6500 BTU/day

So, the questions.

1. Does the capacity of the system as planned seem adequate for the planned use?

2. Would the Frigoboat keel cooler be recommended in addition to or instead of the air cooled system. Frigoboat tells me the keel cooler and air cooled units can be installed in series and the fan turned for higher efficiency.

3. Anything new in insulation better than the Dow polystyrene?

4. I have read that after 4" of insulation you start reaching diminishing returns. Would you agree or should I go for 5" or 6"

5. Any recommendations on the thermostat?
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Old 11-10-2011, 21:21   #2
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Re: New refrigeration system plan

Aerogel for insulation.
We're going to use Cryogel pretty soon.

Cryogel™ : Pacor Inc., Insulation Specialists
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Old 12-10-2011, 07:38   #3
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Re: New refrigeration system plan

Quote:
Originally Posted by senormechanico View Post
Aerogel for insulation.
We're going to use Cryogel pretty soon.

Cryogel™ : Pacor Inc., Insulation Specialists
Have seen this mentioned before but seems pretty expensive compared to other options. Before investing a lot of money in a relatively new product would want to know more about it but have been unable to find much on the website other than pricing. I see one comment that Cryogel is hydrophobic but no data, tests or numbers to back up the claim.

Would be very interested in your experience with the material or can point me towards additional information.

Thanks
Skip
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Old 12-10-2011, 07:58   #4
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Re: New refrigeration system plan

You should always build 6" of insulation around the entire Ice Box and put 4" in the lid. However, your box is way too big. You could do with half that and be better pleased. Remember that a box works better when totally full of food, empty space is a bad thing. Good luck
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Old 12-10-2011, 08:09   #5
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Re: New refrigeration system plan

Quote:
Originally Posted by sailorman14 View Post
However, your box is way too big. You could do with half that and be better pleased.
I choose the volume of the box based on several criteria.

1. available space in the boat.

2. My personal usage based on several years liveaboard.

3. Personal preference in diet, ie fresh fruits, vegetables, salads, etc that require a lot of space in the box and die pretty quickly without refrigeration.




Quote:
Originally Posted by sailorman14 View Post
Remember that a box works better when totally full of food, empty space is a bad thing. Good luck
Sailorman14
Thanks. Am already aware of the issues with empty space.


Quote:
Originally Posted by sailorman14 View Post
You should always build 6" of insulation around the entire Ice Box and put 4" in the lid.
Thanks for this as well. What type of insulation are you using to recommend 6"? Can you refer me to any test results showing the difference in power comparing a 4" vs 6" box? How much additional savings in amp hours per day could I expect.

I agree that 6" is better than 4". My question is how much better.

Skip
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Old 12-10-2011, 08:15   #6
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Re: New refrigeration system plan

Quote:
Originally Posted by sailorman14 View Post
You should always build 6" of insulation around the entire Ice Box and put 4" in the lid.
That would be nice but not always practyical

Quote:
However, your box is way too big.
Have you a reason why apart from possibly the insulation as you mentioned before?
Not a big enough refrigeration unit perhaps?

Quote:
You could do with half that and be better pleased.
Cut the 220 litres down to 110 and be well pleased?
I would be mightily pi$$ed off if I had to settle for that
My last boat had more refrigeration and it was no where near enough,

Quote:
Remember that a box works better when totally full of food, empty space is a bad thing.
I know people who filled space with 2 litre square plastic milk bottles full of water and others that filled the voids with empty but inflated wine bladders, all saying they had good results.
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Old 12-10-2011, 08:19   #7
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Re: New refrigeration system plan

Quote:
Originally Posted by senormechanico View Post
Aerogel for insulation.
We're going to use Cryogel pretty soon.

Cryogel™ : Pacor Inc., Insulation Specialists
While it appears expensive it seems that you get a lot of it for your $600
Quote:
Thickness: 5mm
Part Number: CG 5201-45
Nom Width (in): 57.5
Length (ft): 45
And is it really only 5mm thick and how do you use it?
Just build a liner and fix this to it with contact cement perhaps?
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Old 12-10-2011, 08:33   #8
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Re: New refrigeration system plan

My thinking is that if I were cruising and my mechanicals went out for any reason, couldn't fix it, how much insulation would I like to have? I'm sure there is a financial break even (which is pretty slim I would think) but that would not be an issue with me, how much in the what ifs would carry more weight.

Next, is that the unit would not kick on as much if it were better insulated. I would think too there would be many micro considerations such as placement of the unit, will the sun ever hit it, will it be close to a heating source and so on. Again, the more there is seems it would perform better.

If the box insulation is expensive, adding cheaper insulation beyound that can't hurt. So I think I'd fill the space outside the box to the point that it doesn't begin to steal usable space in any cabinet or interior.

You might need to turn it into an ice chest some time, so I'd go with all the insulation I could get. IMHO
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Old 12-10-2011, 08:37   #9
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Re: New refrigeration system plan

Quote:
Originally Posted by cat man do View Post
While it appears expensive it seems that you get a lot of it for your $600


And is it really only 5mm thick and how do you use it?
Just build a liner and fix this to it with contact cement perhaps?
Dow blue board, about $25 for 4' x 8' x 2" (50 mm) thick. A fraction of the cost of the aerogel and a lot less work installing 4-6" in a box.

Max thickness I saw for the Aerogel was 10 mm ( less than 1/2").

So Aerogel for the same quantity of insulation will be 50-80 times more expensive than Dow polystyrene but totally would depend on how much Aerogel one would use to match the same R-value of Dow foam.

So far I can find nowhere on the Aerogel website a spec on the R-value. The only statement I see is a claim of 2-8 times the thermal performance of the "competition" with no information on what they consider the competition.

I also would like some information on the long term resistance to moisture absorption. If the stuff gets wet after a few years then it has pretty much lost its insulation value.

Generally I get very suspicious when a producer doesn't publish specs or data on their product.
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Old 12-10-2011, 08:42   #10
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Re: New refrigeration system plan

Quote:
Originally Posted by cat man do View Post
While it appears expensive it seems that you get a lot of it for your $600


And is it really only 5mm thick and how do you use it?
Just build a liner and fix this to it with contact cement perhaps?

http://www.aerogel.com/products/pdf/Cryogel_Z_DS.pdf

You can laminate it layer upon layer using adhesive or epoxy. It also comes in a 10mm thickness which is more suitable. I just did my reefer with 5 layers of the 10mm (2 spaceloft sandwiched between 3 cryogel) on the sides and top and 7 layers on the bottom.

I can't test it until spring as my boat is on the hard with the batteries removed, and it's chilly at night here in Michigan anyway. I used it because I have limited space (Wauquiez Pretorien) and ended up with a 4.5 cu. ft. refrigerator which should work just fine with my Cold Machine.
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Old 12-10-2011, 08:43   #11
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Re: New refrigeration system plan

Quote:
Originally Posted by Wavewacker View Post
My thinking is that if I were cruising and my mechanicals went out for any reason, couldn't fix it, how much insulation would I like to have? I'm sure there is a financial break even (which is pretty slim I would think) but that would not be an issue with me, how much in the what ifs would carry more weight.

Next, is that the unit would not kick on as much if it were better insulated. I would think too there would be many micro considerations such as placement of the unit, will the sun ever hit it, will it be close to a heating source and so on. Again, the more there is seems it would perform better.

If the box insulation is expensive, adding cheaper insulation beyond that can't hurt. So I think I'd fill the space outside the box to the point that it doesn't begin to steal usable space in any cabinet or interior.

You might need to turn it into an ice chest some time, so I'd go with all the insulation I could get. IMHO
In general this is all exactly right and no disagreement but I'm trying to get some specifics. At some point in the process the benefits of additional insulation do not justify the cost, hassle and lost storage.

Where is that point?

For example, I think it would give almost no benefit to go from 10" to 11" of insulation. But what about from 9" to 10" or 6" to 7" or , more realistically from 4" to 5" or 6". Where is the break where the additional inch does not give a reasonable improvement in the energy loss?
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Old 12-10-2011, 08:53   #12
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Re: New refrigeration system plan

Quote:
Originally Posted by skipmac View Post
Have seen this mentioned before but seems pretty expensive compared to other options. Before investing a lot of money in a relatively new product would want to know more about it but have been unable to find much on the website other than pricing. I see one comment that Cryogel is hydrophobic but no data, tests or numbers to back up the claim.

Would be very interested in your experience with the material or can point me towards additional information.

Thanks
Skip
We are going to use a mixture of Aerogel and Cryogel because we need every cubic inch of box space that we can get.

Steve
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Old 12-10-2011, 08:57   #13
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Re: New refrigeration system plan

Quote:
Originally Posted by senormechanico View Post
We are going to use Cryogel because we need every cubic inch of box space that we can get.

Steve

In your research have you been able to learn the claimed R-value for Cryogel? I can't seem to locate it anywhere on their web site.
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Old 12-10-2011, 09:00   #14
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Re: New refrigeration system plan

Quote:
Originally Posted by cat man do View Post
While it appears expensive it seems that you get a lot of it for your $600


And is it really only 5mm thick and how do you use it?
Just build a liner and fix this to it with contact cement perhaps?
We're going to build an interior liner, attach two layers with contact cement and cover it with foil for a radiant barrier.
We'll slide it in place having built out from the cabinetry (where space available) with a bit of foam, especially from the hull side.

Steve
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Old 12-10-2011, 09:13   #15
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Re: New refrigeration system plan

Quote:
Originally Posted by skipmac View Post
In your research have you been able to learn the claimed R-value for Cryogel? I can't seem to locate it anywhere on their web site.
I am not sure, but I seem to remember that R value is the inverse of thermal conductivity.
There's a chart here:

http://www.aerogel.com/products/pdf/Cryogel_Z_DS.pdf

Steve
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