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Master Mariner
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Discussion Starter · #1 ·
So we've got one of those old fashioned refrigeration boxes from the 80's. It's very deep, oddly shaped with a shelf between the top and bottom. We only use the bottom when preparing for a crossing; the rest of the time it's wasted, cold space. We've tried cutting Styrofoam pieces to fill the space, pillows in plastic bags and a few other things, all with varying degrees of unsuccess.
Does anyone have any thoughts on what we could fill this space with, that would be removable, yet keep most of the cool in the top section? Keep in mind that any condensation on the plates must drain down through the bottom, so a sealed shelf wouldn't work.
Thanks.
 

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formerly 'BoatyardBoy'
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Make a sealed shelf with a drain in it with a hose going to the lower drain.

Or, put soon water bags in the bottom, once they get cool, they will hold the cold longer so your compressor isn't always running. A empty fridge is the best thing.

Sent from my HTC6500LVW using Tapatalk
 

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Owl
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Keeping the fridge full of thermal mass is the best strategy for sustained operation. "cold loss" is proportional to the surface area (and leaks, etc) of the box, not the amount of empty space in the box. "Keeping the cool in the upper section" probably indicates a misguided mental model. You can't do that effectively, the cool will seep down into the lower section anyway. What you want to do is minimize the temperature change inside the box when you open the door, for two reasons. First, to prevent temperature changes in your food, which will hasten their demise, and second, to prevent the compressor from cycling on and off. It consumes a disproportionate amount of power each time it starts.

However, for day sails, perhaps you don't want to run the compressor to cool off a bunch of warm thermal mass, and you just want to cool the relatively smaller mass of your lunch and two cans of pop. In this case, you can take one of two different approaches:

1. fill up the lower area with something with as little thermal mass as possible, so it won't take long to cool off. Air works, or better yet, vacuum, but that's trickier.
1a. To fill the lower space with only air, you could construct a shelf with holes through it for drainage, and adjustable feet so you can level it on the bottom. I'm guessing the bottom has one section that is a foot deeper than the rest, so I'd make short legs and long legs to fasten to the shelf. Trimming a fridge rack to shape might create a good shelf.
1b. To fill the lower space with vacuum, you'd need to construct a sealed volume and evacuate it. I'm running out of patience to write up how I would do that.
1c. As an intermediate solution, you could find a substance with less thermal mass than ambient air but more than vacuum, and fill the space under the 1a shelf with that. Here's an idea: mylar balloons filled with helium. The shelf would bear the weight, water would drain between the balloons, and helium is going to have quite a bit less thermal mass than N2+CO2+H2O+O2.

2. fill up the lower area with something with lots of thermal mass *that is already cold*. This substance would need to be firm enough to support the weight of your day's provisions, and ideally should be readily available. What most boaters use for this purpose is a rectangular block of ordinary H2O in solid phase. Coincidentally, this substance is usually sold at every waterfront grocer in one of two sizes, under the generic name "ice block". One "ice block" lasts for an entire day sail, maybe two, and your compressor will not cycle at all.
 

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Discussion Starter · #5 ·
Once again I see I posted a poorly written explanation of the situation.
There is already a plexi shelf there, which is in two pieces, side by side. It has numerous holes in it and it has everything on it that we have in the fridge, so accessing the bottom section is a pain, removing everything on half the shelf, putting the items on the counter, etc.
We have a 110v system, so there's no cycling, it is run twice a day for an hour or so.
This thing is so deep I cannot reach the bottom with my arm, but as it follows the hull shape, there is no flat bottom. The entry hole (in the top) into it is only about 1 square foot, so building anything like a sealed shelf would require a complete rebuild of the thing, from the top down, so that's not happening, right now. One day, finances willing, it will, when we switch to 12 volt.
So, this far it seems even the Styrofoam is of no value in taking up space down in that hole. I had thought to try and reduce the internal volume of space needing cooling with the Styrofoam or pillows, etc, but from the responses, I guess without a sealed separator or helium balloons, I'm wasting my time, and the few brain cells I have left.
No simple solution, I guess
 

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As I'm understanding your situation, you'd have to rebuild the box and make a smaller area. Barring that, the Styro blocks or other foam insulation would be the go but you'd have to take time and fit the blocks so they'd fit tightly and seal the area off.

I worry about cold going out the top. So I have a pillow made of Styro beads, and then over that a 'blanket' of aluminized Mylar (windshield sunscreen) sewn to a vinyl backing. These things help, as do making sure that your drain is plugged when the unit is in use.

See The Boat Galley dot com for refrigeration efficiency suggestions - maybe she'll have something to help you
 

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I'm wasting my time, and the few brain cells I have left.
No simple solution, I guess
Well I like the idea of beer, but I guess that will do in those remaining braid cells!

On a serious note. I have read that you should "fill" up as much space as possible with stuff to reduce the air space. I am not sure if it is better for it to have it have mass, like beer or just plain water jugs, or for it to be like Styrofoam with no mass to cool. What has been the issue with Styrofoam? Seems like if you could get a block of it, and carve it to fit, perhaps in a few pieces it would fill the area. Mass though it seems would help keep the temperature swings down so I don't know. Again you can never have too much spare beer.
 

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formerly 'BoatyardBoy'
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Styrofoam will just reduce the volume of empty space. Like a vacuum off area. Jugs or flexible water jug bags at the bottom under your plexiglass would probably be your best bet. Once they are frozen from running on the 110v they will hold the cold much longer than Styrofoam would. It would be like in the old days when fridges were called ice boxes because they actually had a giant block of ice in it that you had to buy. Just my opinion, we use frozen gallon Jugs of water in ice chests because the stay frozen longer than bag ice you buy.

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Capta -
if you already have a shelf halfway down, the probable most efficient way to contain the 'cold' is to insulate the bottom face of the shelf and then seal it against air leaks into the empty bottom section.
You will still need a drain for the shelf but that drain MUST be with an 'air-trap', similar to a standard S shaped sink trap - to trap the cold air from 'draining' into the lower section. You must routinely fill the S-bend with water to keep the 'air seal' intact --- we typically refill the 'air-trap' every time we de-frost.
An air trap on all boat refrig/freezer systems will prevent the drainage of cold air. Without such an 'air trap' the colder air will continually sink to the bottom and drain out into the bilge. The lack of an 'air-trap' ranks among the chief culprits for refrig. performance efficiency.

Secondarily, Id additionally fill the empty bottom section with 'bubble wrap' to increase the R-value of the whole space. Cheap, Easy to install, disposable, and will lessen heat value differences due to convection. Bubble size doesnt matter.

:)
 

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Capta is cruising in the tropics as I am, so the advice for day sailors isnt applicable.

I have this vexing problem in spades... I have two huge fridges and one small fridge freezer and can only use the small fridge freezer in fridge mode due to power consumption and cycling on together at night trips the compressor off of the big one. The two big ones are now never used!

I have been using a variety of foam type ideas, including a cool box with the lid taped closed on it. In the small fridge freezer I have some cut bits of closed cell foam to decrease the volume and put the stuff to be coldest against the cold plate. But its not very good.

Having water or beer in there sounds like a great idea however it takes a lot of electricity to keep it cold compared to lesser volume. Remember in the tropics the 24 hour per day ambient temp is about 30 C!

If capta drifts past st martin and goes to Kooyman Hardawre there as variety of foam sealers designed to insulate cracks by squirting the can into the gap which turns to foam. I have been toying with the idea of squirting it into a mould so I can have control of the exact shape. Each can cost about $10-$15
In the bottom of the fridge of capta's it may work to squirt the foam into a plastic bag and then gently stuff it into the space. Once it has cured you would have a removable block of foam fitting exactly that space.
However, I havent tried it so I dont know if it will work.

I would certainly be pleased with a better solution!

Refirgeration and freezers on the cruising boat is the biggest bloody headache. I would love to have a sneaky supply of ice-cream and a few frozen steaks but a better system to allow it can really cost several thousand dollars! I am looking at a much bigger house bank... And more solar to keep it charged... Which needs a bigger solar regulator... And maybe a wind generator to give some into the batts at night ... And a regulator for that... ... ... ...

I need a cold beer just thinking about it! :eek:

Mark
 

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Capta is cruising in the tropics as I am, so the advice for day sailors isnt applicable.

I have this vexing problem in spades... I have two huge fridges and one small fridge freezer and can only use the small fridge freezer in fridge mode due to power consumption and cycling on together at night trips the compressor off of the big one. The two big ones are now never used!

I have been using a variety of foam type ideas, including a cool box with the lid taped closed on it. In the small fridge freezer I have some cut bits of closed cel foam to decrease the volume and put the stuff to be coldest against the cold plate. But its not very good.

Having water or beer in there sounds like a great idea however it take sa lot of electricity to keep it cold compared to lesser volume.

If capta drifts past st martin and goes to Kooyman Hardawre there as variety of foam sealers designed to insulate cracks by squirting the can into the gap which turns to foam. I have been toying with the idea of squirting it into a mould so I can have control of the exact shape. Each can cost about $10-$15
In the bottom of the fridge of capta's it may work to squirt the foam into a plastic bag and then gently stuff it into the space. Once it has cured you would have a removable block of foam fitting exactly that space.
However, I havent tried it so I dont know if it will work.

I would certainly be pleased with a better solution!

Refirgeration and freezers on the cruising boat is the biggest bloody headache. I would love to have a sneaky supply of ice-cream and a few frozen steaks but a better system to allow it can really cost several thousand dollars! I am looking at a much bigger house bank... And more solar to keep it charged... Which needs a bigger solar regulator... And maybe a wind generator to give some into the batts at night ... And a regulator for that... ... ... ...

I need a cold beer just thinking about it! :eek:

Mark
Well my thought was that perhaps once cooled the beer or water would help keep the box cool as there would be more mass to have to heat up. Yes the initial cooling would certainly take more power to cool down but perhaps take less to maintain it once cool. Though I think the 110 volt may complicate that as it only runs twice a day so it may get too warm and need to be cooled back down.

The idea of the expanding foam could work well. We use it at work, but use a two part chemical that is mixed in a gun and sprayed in place. We make molds for electronic equipment. (Cash register systems) You can just put the bag in the bottom box, and spray it into the bag and let it fill up in the box, it will form to the shape of the box. The one thing I will say is that excess can be trimmed with a knife or saw blade, but the edge of the trimmed foam is quite open celled and will absorb moisture like a sponge. Not sure how you could keep it dry. If it is not trimmed it has a quite water resistant skin on it. I have had luck trimming it with a serrated knife or a hack saw blade taken out of it's frame. The only issue I see is that he would have to allow for moisture to drain to the drain in the bottom. Perhaps put in a bit of hose before spraying the foam.
 

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Really. Check out The Boat Galley. She has tips that fit your bill exactly. I've found her reefer suggestions to be of great help.

One of which is to keep drinks and things frequently 'grabbed' for OUTSIDE the fridge, in a chest on deck. So you're not constantly letting the cold out/heat in by opening the fridge all the time
 

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I've found her reefer suggestions to be of great help.
I did not know you lived in CO or WA?!?!?!? :laugher:laugher

reefer madness.....

I do like her web site, very helpful, and not just for a boat galley I have used some of her ideas in other small kitchens.
 

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Owl
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Once the fridge has reached operating temperature, it requires precisely the same amount of energy to maintain operating temperature no matter whether it is full or empty. The difference is in how much energy it takes to reach operating temp in the first place - obviously that will be much greater for a fridge full of warm beer than a fridge full of warm air, or warm air and helium balloons ;)

The equation is simply "BTUs heat infiltration == BTUs heat extracted by cooling unit". It matters not how much beer is in the fridge.

What you have to ask is "how does the heat get into my fridge?" Well, it comes through the walls, and through the door. If there are any cracks in the insulation around the box, it comes through those, and through leaky gaskets around the door.

The great thing about the 80s cold boxes is that they open from the top. This keeps most of the cold air inside the box, versus a front-opening fridge.

So you want to insulate the entire surface area of your cold box. It's probably impossible to insulate the outside of it, so I would try taking that styrofoam and building yet another insulated box *inside* your cold box, with a small drain at the bottom. (Incidentally, your drain has a valve on it, right? An open tube will drain cold air away.) It will be tricky working through a 1ft^2 hole. You'll want to use some kind of sealant around the seams of your box to prevent any kind of air movement.
 

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Capta,

A space filler does not have to be an inert lump.

How is your fridge box situated in the boat? Is there a "front wall" that is accessible?

The reason for the question is that the fridge on my boat faces onto the space in the galley and has a "front wall". Our fridge was exactly as you describe yours, too deep to really reach the bottom, shelves that have to be removed to get to the bottom half, almost impossible to clean. A general PITA.

So I cut a hole into the lower half of the front wall and through into the fridge cavity. I designed and built a stainless steel drawer unit that plugs into the hole and slides out into the galley space. It is properly insulated and fills the whole of the bottom half of the cavity. And it works brilliantly well.

I don't have pictures of it fitted to the boat but this is the rendered drawing off my CAD package, This the drawer closed:

This is the drawer open:

The channel frame around the body of the drawer is sized to the aperture size and also the thickness of the fridge wall. The front fascia is backed by 70mm of foam.

Nett result: a fridge that I can load up from the top and never have to move stuff to get to the bottom because the bottom half is full of drawer.

If this would work for you and you're interested, PM me and I can send you the design drawings and DXF files (profiling shop will need those to cut the components). You will also need some TIG skills or know someone who does. But the installation is simple and as said works brilliantly well.
 
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Cold air is denser than warm, so it goes down. Unless you seal the bottom of the box off totally air-tight, you will lose cold air no matter what you stuff in there. Probably out the drain in bottom, too.

I'd suggest filling the bottom with a good insulator, low density foam or low density expanding foam "spray" that you can spray into a contractor grade plastic bag, so it doesn't bond to the box. Install a false bottom right on top of that, and make sure it is 100% sealed around the edges using real metal duct tape or gutter tape. Sealed, 100% airtight.

That's all you can do, and the best you can do, to isolate the bottom of the box. Of course that leaves you with no provision for the drain, you might want to add a hose for that before you seal things off.

It is very possible that you are losing heat [sic] through the sides of the box. If they are poorly insulated, as typical, sealing off the bottom won't matter much as the cold continues to get lost through the sides. You may want to try accessing around the outside of the box, and fill that space with new low-density expanding foam, or a similar good insulation.

Then you throw a thermal blanket on top of the food, because no doubt the lid is also not up to snuff.
 

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I'd suggest filling the bottom with a good insulator, low density foam or low density expanding foam "spray" that you can spray into a contractor grade plastic bag, so it doesn't bond to the box. Install a false bottom right on top of that, and make sure it is 100% sealed around the edges using real metal duct tape or gutter tape. Sealed, 100% airtight.
Yes, but the original poster said . . . . .

Does anyone have any thoughts on what we could fill this space with, that would be removable, yet keep most of the cool in the top section? Keep in mind that any condensation on the plates must drain down through the bottom, so a sealed shelf wouldn't work.
. . . . and a block cast into a plastic bag in the bottom of the fridge will only be removable with considerable effort and some sharp tools.

Fact is, if you're planning to fill the bottom (which just in case nobody noticed reduces volume by half), more than one block of polystyrene foam tightly assembled in the bottom will give you the best insulation of all the readily available affordable foams and putting a two-piece solid deck on top and sealing the edges is a walk in the park. Making it airtight is moot because the integrity of the original box is not being breached. Later removal of the deck will reveal easily removable blocks of foam so the original size of the box is preserved.

My approach was to use the bottom half, not lose the bottom half. Of course as I said in my earlier post, the fridge box location must be conducive else reducing the space by half is the only solution.

In truth, I am intending to do exactly what I describe above with my freezer because it is in any case much too large and it's in the corner with no accessible walls.
 

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Discussion Starter · #18 ·
I want to thank you all for your suggestions. We do have a 1/2 insulator on top because I know the hatches are not well sealed. As to the insulation around the box, I'm sure it was the best available in 1981, but hardly of the efficiency of today's products, I'd guess. At any rate, I can not access any of the area surrounding the box, so who knows what's there?
One thing I did fail to mention; the plate for the fridge is up top under the counter, not along a wall.
The biggest problem is the temperature swings when you do not run the compressor 24/7, only twice a day, so I thought temporarily reducing the volume might help.
12 volt refrigeration would certainly help, but with a 110 volt stove, we have to run the gene anyway, so it becomes a pretty expensive, "do it all right" situation. A propane stove would lead to a total rebuild of the refrigeration system, including new boxes with modern insulation. That would then require more batteries and a windgen, in addition to our present solar array.
From the pic, I'm sure you can see that just the cabinetry alone would be a pretty penny.
So I am looking to an easier and at this point, a cheaper, alternative. If you are my age, you have to balance the huge expenditure of the whole galley renovation versus the gene fuel and the real possibility that that money won't be recouped upon sale of the vessel.
Thank you Omatako, Andre'. I shall contact you as I have considered a door there but the loss of cool upon opening was something I couldn't solve for myself.
On the other hand, should one of you extremely handy folks wish to exchange sailing the Antilles with us for help rebuilding the boxes and the cabinetry work, please PM us.
Thanks again, all.
 

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Omatako, how easily removeable a block cast inside a non-stick liner will be, depends on the shape of the box. But the point is, it will be easily removeable even if that means cutting the block and pulling it out in pieces when someone does want to remove it. Not for daily use--but "easily" removeable when the time comes.

You miss entirely the point that one block, firmly pushing against all sides, will not have any air spaces that may be leaking cold air down. If the box is filled with anything besides one monolithic block, then whatever it is filled with will need to be taped, sealed, joined, blocked, in order to ensure there is no passage for cold air to get through it.

Thus, one block, cast in place, with a non-stick (poly) liner around it so it is easily removed. As opposed to needing to be chiseled free and torn off the box walls.

Airtight is not moot, since we have no idea how much cold air is being wasted out the drain hole, or out the sides and bottom of the original poorly insulated box.

And while you may be using the bottom half, the OP was quite specific about the box being too deep to reach into, and using the top half specifically to correct that problem.

Capta-
Good point about the woodwork. I would guess that the way to sidestep that problem, would be to remove the formica top, and do all your new work from the top, leaving all the sides intact. Or, perhaps to carefully cut 1" in from the sides, and remove almost all of the top--leaving just a one inch margin in place. That would allow you pretty good access, leave all the woodwork intact, and be easy enough to cover with either an inset top, or again recovering the entire top. Very much like dropping a new sink into a kitchen countertop, without disrupting the countertop or cabinets. And probably worth paying a cabinetmaker or finish carpenter if you're not up on the fine points of that stuff. Odds are there's something like a 2" wide board running under all the edges, supporting that countertop and joining it to the sides. You could probably "implode" the icebox and then poke around underneath to see what's in there, to attack it more precisely.
 

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This probably would work better if you were part-time cruising and had a home freezer, but maybe…

I've found these cooler packs called "Arctic Ice" Arctic Ice :: Reusable & Rugged Cooler Packs

In lieu of freezing a plastic bottle of water or some such.

In the OP case since he's offshore, it might work for him to keep a couple of these things living in the icebox bottom and they'd tend to retain the cold with some efficiency. Might work, anyway
 
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