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Old 29-12-2013, 12:15   #31
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Re: Reefer Design

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Originally Posted by Noreastern View Post
Mark, I like this setup. Thanks for sharing.

I would like to down size it for about 2cf freezer and 2cf reefer. If I am reading this correctly you have a fan moving cold air from freezer to the reefer that is separated by 1 inch and that both boxes are insulated with 6 inches?

Brian
Yes, there is an insulated 1" divider between the freezer and the reefer sides of the box. Near the top of each end of the divider are 1.5" holes. One hole has a thermostatically controlled fan on it (common small computer fan) and the other is a passive return. When the reefer needs cold air, the thermostat causes the fan to blow air off the top of the reefer compartment into the freezer compartment and exchanges cold air from freezer to reefer through the passive hole. It really doesn't matter which way the air flows, but having the fan draw from the warmer reefer air instead of the colder freezer air keeps it from seizing due to frozen moisture.

It is only a single box with that insulated divider being the difference between "reefer" and "freezer" sides. The box has 6" of poured polyurethane foam around all sides. The box is made of 1/2" Nidacore, except the front of the box, which is 1.5" Nidacore (I forgot that the front of the box is the back of the main beam on our catamaran). The Nidacore probably adds R2-3 to the insulation.

Since you are building from scratch, you may consider having a bit better insulated divider - maybe 2" instead of 1". Also consider designing it so that when the fan blows, the air gets tumbled through the reefer and gently distributed through the freezer. On ours, the fan blows reefer air onto the back of the freezer evaporator plate, which makes it gently distribute around the box in the small standoff space between the box wall and the evaporator plate. The cold air entering the reefer enters behind a basket, which forces it downward and around the box.

Having the freezer box completely surrounded by evaporator plate is very efficient in obtaining low temps. Custom sized and bent plates are available from many manufacturers for little to no extra cost. I never understand why they do not advertise this more (or better), because most people do not know it and settle for small bin evaporators instead.

Mark
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Old 29-12-2013, 12:23   #32
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Re: Reefer Design

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Originally Posted by SV THIRD DAY View Post
Mark,
The more photos of I see of your boat and the well laid out systems, the more envious I become, so I can't wait to see the length extensions you are planning!

That is a dream box set-up in terms of insulation, location, and daily Amp hour usage. I know many cruisers that have a much smaller total box volume but with no exaggeration use 150AH for their refrigeration and are cryin the blues trying to keep up with the daily power usage.

It goes to show a real life example of just what Insulation along with a good box design can do for you! Thanks for sharing.
Without a doubt, the Manta catamaran has the best-designed, built, implemented and accessible systems ever on a boat this size. Wiring, plumbing, fuel, electrical, chases, mountings, etc. I thank Manta every time I have to work on, or add to, one of their systems. And every time I step foot on a French catamaran.

Except for that guy at Manta with a 5200 fetish. I curse him.

Mark
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Old 29-12-2013, 12:29   #33
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I don't have any data on the drawer types, but I have installed one and can make an informed comment. Since the drawers are relatively closed (not water tight), a small a...
What make/model of fridge is that?
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Old 29-12-2013, 12:50   #34
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Re: Reefer Design

Vitrifrigo, model DTX180. Top drawer is the freezer, bottom is the reefer.
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Old 29-12-2013, 14:07   #35
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Re: Reefer Design

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A question for the reefer gurus here. If you were planning a new install of fridge and freezer (separate or spill over) on a custom new build to be set up for 2-6 people for long distance cruising in tropical waters, what would be your choice of system? You would have easy access during the build, lots of space and could build the system you want (albeit whilst trying to save money of course).
You are in Australia correct?

If so contact Malcolm at ICEER, he is in Brisbane see ICEER. His fridges and or freezers have been on hundreds of Seawinds, and the owners, myself included will all tell you it is one of the best things on the boat. Aside from that he is a very nice chap and a thorough gentleman to deal with.
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Old 29-12-2013, 18:52   #36
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Re: Reefer Design

Does anyone have any input on the Rparts vacuum panels? They have quite a deal on a few select sizes.
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Old 29-12-2013, 19:31   #37
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Re: Reefer Design

Just make sure they commit to a delivery time....there have been reports of people waiting for months for orders to fill from Rparts (for box hatch opening).


At the price shown....WOW...those are blow out prices.
RPARTS.COM - Vacuum Insulation Panels - www.rparts.com

The only thing "worrying" with Vac pannel insulation is that if the panels ever get damaged....ka paw...you have Zero insulation now from that panel. And now your box is designed and built for 1" of insulation...so how are you going to re-do it for 4-6" of old school foam?
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Old 29-12-2013, 19:45   #38
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Re: Reefer Design

Well you'd still have 1" of whatever is in the vacuum I assume at least r5 and then most people put an inch or so of foam on each side so you'd have still a good bit of insulation.

I've never been that big on them myself, but I really have a space crunch if I want to put the system in the hull and not on the bridgedeck.
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Old 29-12-2013, 19:59   #39
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Re: reefer design

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Originally Posted by Richard Kollmann View Post
Doe818, You must make several decisions before selection size and type refrigeration unit for a box conversion to refrigeration/freezer.

Cruising area temperatures? Tropics.

Number of people onboard? 2 to 6

Desirable amount of insulation R30, approximant planned R value of insulation? __________.

Where will energy come from to support refrigeration? _________.

What is the desired size of refrigerator area you need after box is completed? _________.

What is desired size of Freezer area you need? _________________.

A 4 cubic ft (133 Liter) combination box in a tropical climate with 2 people will need about 10 amp-hrs per cu ft refrigerated space per day and 20 amp-hrs per cu ft of freezer space per hour per day. These amp-hrs will be again increased by at least 2 amp-hrs per cu ft by addition person above 2 on board per day do to cold liquid consumed and ice per day.
Actual energy consumed will depend on the temperatures you desire in the two separate refrigerator freezer areas. The above 4 cu ft box example would be at constant mid to high 30s F refrigerator temperatures and +10 to +15 degree F freezer temps.

It is difficult to design a spillover system that provides stable controlled temperatures.

I suggest you do the math on my web site slide show for the concept you come up with, then select a compressor with capacity needed and its largest evaporator for your special design. Also for more info on spillover click on FANS for spillover systems.
A couple I know did a redesign of their old refer space with a spill over, complete with much better insulation and a larger compressor and cold plate. They said the problem with the spill over was "The dimensions and location of the drain and spill-over air holes in the divider had always been a bit of an educated guess......not very scientific....and they'd never been verified." They added a fan but weren't happy with the results in their system. "We tried the fan in several different locations but quickly discovered that rather than helping things, the fan was actually aggravating the problem by disrupting the natural convection cycle." What made the difference for them was changing the analog thermostat to digital. "The new thermostat immediately made the difference between night and day. The Carel controller operates instantaneously at the programmed on/off set points and the the system temperature is very stable. The compressor cycle frequency has dropped significantly, it only runs for 30 minutes three or four times a day, and that has helped with power management when we are away from the dock. Bottom line is that the conversion was a very worthwhile upgrade."
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Old 29-12-2013, 20:21   #40
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Re: Reefer Design

You might consider using Aerogel insulation instead of any of the foams. Has twice the R value per inch. Expensive but if I were starting from scratch I would use the best insulation I could get.
Industrial Insulation, Insulation Fabricators ? Pacor, Inc.
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Old 29-12-2013, 20:40   #41
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Re: Reefer Design

I forgot to mention that our freezer and reefer both use digital thermostats.

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