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uri go
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Hello everyone,

I am not sure if I am posting in the right place.

I am in the process of building an off the grid tiny cabin. I am sizing my solar system and found out that my mini fridge will so much power that I could get a system a quarter the size if I went without it.

Now, I am trying to find out if I can maybe make an "ice box" or faux fridge myself. Anyone read or know anything about doing something like that?

This cabin will be used every other weekend and we can bring ice packs/ ice bottles with us for the weekend. I thought about making a super insulated box or cabinet that I will then place the cold pack into.

Any help will be greatly appreciated.

PS - I read about the chest fridge thing but I am not sure I want to take that route also I learned that that method with the external thermostat has issues.

Thanks!
 
Adam Poddepie
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Making a no-electricity refrigerator sounds a little tricky. What's the humidity like in the area?

You could also consider digging a root cellar, but I don't know the conditions in your area. A permanent ice box would probably work fine with enough insulation.
 
R Scott
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Location: Kansas Zone 6a
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It is EASY to build a super-insulated box these days--a bunch of blue or pink foam and a can of spray foam to seal the joints. You can find any number of examples on youtube or the internet.

the answer I like budget-wise is to get one of these: http://www.amazon.com/gp/product/B000N6302Q/ref=as_li_ss_il?ie=UTF8&camp=1789&creative=390957&creativeASIN=B000N6302Q&linkCode=as2&tag=knowledgepubc-20

The idea is you make ice on bright sunny afternoons when you have extra power.

You could go full Amish and make 50-100 lb ice blocks in the winter. Stored in a superinsulated ice shed, they will keep all summer.
 
Glenn Underhill
Posts: 95
Location: NW Montana
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I found this on http://www.instructables.com/id/Build-an-ultra-efficient-fridge/ instructables awhile ago. Its best for the winter time, but basically you take a fridge, cut some ducting holes in it, connect with some insulated ducting through a wall or window to the cold outside, and use a low powered fan to circulate the outside air through the fridge.

Also there are some really low energy refrigerators out there, I keep this site bookmarked.

EG: "Introducing the BFR105, a battery-free version of our 165 liter chest refrigerator with built-in thermal storage packs.

This refrigerator maintains cold temperatures for 4-5 days without the need for a battery! It contains a built-in ice bank that freezes when the sun shines. It acts like a battery, but will never wear out. It cannot be damaged by overcharging or undercharging like a normal lead acid battery. The higher initial cost replaces what you’d spend on your first battery and charge controller. After that, there is no scheduled maintenance for the life of the refrigerator other than normal cleaning." Of course that fridge costs $1450 so its just an idea.
 
Kathy Burns-Millyard
Posts: 75
Location: Arizona low desert
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For weekends why not just use a good quality cooler? We have a coleman that claims up to 5 days of cold that works well enough. If we fill it with ice blocks and frozen meat it keeps everything at least 3 days even in 80+ degree weather.

In the summer after the ice melts we use it for evaporative cooling. Just an inch or two of water in the bottom and leave the lid open. In 100 degree temps we can knock 30 degrees off drinks and such pretty easily. No power needed
 
Adam Poddepie
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Oh yeah, definitely +1 to Glenn. Chest fridges are going to retain better temperatures upon opening since the cold air will have nowhere to fall to. It may be a bit pricy, but that's definitely a nice option.

Scott, your idea is very interesting. How long would it take to make enough ice blocks for it to work?

Building your own fridge (cooler) is definitely the least costly option, and I'm sure it'd be a ton of fun.
 
Glenn Underhill
Posts: 95
Location: NW Montana
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I always try to think what they did 200 years ago. Dick Proenneke in Alaska basically dug a hole in the ground and covered it up in "alone in the wilderness'. But he had permafrost. The climate and ambient temperature makes a difference. But I think the root cellar is a good long term idea. When I do my thing next spring I'm going to have a small fridge and a big root cellar, accessible directly from the house. Its ridiculous that in the winter we use huge electricity to keep our food cold. I have Thomas J. Elpel's book "Living Homes" and he wrote about how he was going to have a pond north of the house. After winter came and froze it solid, he would bury it in straw. In bottom of the pond would be heat exchange pipes running in a loop to the refrigerator in the house. (Fridge on the north wall of the house for that reason and because its cooler there). He said if the pond was insulated enough in the summer it would stay mostly frozen all summer long. So the only energy expended is in piping the cool temperature to the fridge somehow. He never got around to building it but I wonder how it would have turned out.
 
Glenn Underhill
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Location: NW Montana
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By the way, the Amish (in this area anyway) use propane refrigerators noawadays, haha. But they seem to have a lot more money than we do!

But a small RV type fridge/freezer goes a long way on a little propane.
 
R Scott
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Location: Kansas Zone 6a
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More a matter of how many molds you want to buy and deal with. The amish down the road have the kids deal with them every day when it is COLD, but maybe several days if it is not that cold. It is something you could fill up before you leave, let it freeze all week, then pull them out and put them in storage when you get there the next week. Adjust your number of molds for how much you want to make. They have a 10x10 walk-in "fridge" and spent $400 to buy iceblocks the first year. $400 a year for running a walk-in seems like a deal to me no matter how you do it. I have been debating doing the same thing and just putting the blocks in house as supplemental AC.

You want the blocks to be almost cubes--as thick as possible and just enough taper they will come out of the mold. I have done it using dishpans as molds for one or two, but they will not last. I haven found a cheap easy mold idea. The amish made theirs out of metal so they could bang them around and not worry about the mold breaking.
 
Glenn Underhill
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Location: NW Montana
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I like the idea. Simple is good. How much insulation do you think the shed would need? Straw bales could be used for this. If the shed was partially buried like a root cellar it would help. Just have to keep moisture out of the bales. Would one bale thick, buried with earth in a hill be enough? With bales stacked two thick against the door?
 
R Scott
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They built it with blueboard (with seams foamed and taped), then fiberglass, then another layer of foam, then 4" airgap, then galvanized tin. That was the sides. The top was about the same, but the tin was on a shallow pitch with the gables open to catch prevailing wind.

Theirs was built on stilts for airflow underneath for two reasons: 1) easier to make rodent resistant and 2)bedrock was just 3 foot down.

One of the keys is packing the ice in wood shavings: 1)to wick away any moisture from the blocks (dry blocks melt slower than wet ones, even just standing in air) and 2) to provide evap cooling for the whole structure. For that to work you need controlled ventilation and drainage. I didn't get good answers from him on how he did that.
 
Devon Olsen
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Location: SE Wyoming -zone 4
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glen thank you very much for that link, i clicked on it immediately before finishing your post and found the battery free model, got excited and was about to share it before irealised you already have:p
 
Rufus Laggren
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This problem on a small scale has been part of cruising boat life for a long time. Search "boat, refrigerator, (DIY OR homemade OR insulation OR build OR shell)" and you should find a lot of info and ideas. The basic concepts last I looked included lots of insulation, _very_ careful door seal design and build, top lid, and coldplate cooling system.

IIRC 4" foam insulation is the start of diminishing returns. The interior shell is the most important because it gets the most abuse (read spills, wear, regular moisture). A drain can be a great convenience but is really hard to design in a way that doesn't let heat in.

Rufus
 
Adam Poddepie
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Rufus, for a drain, couldn't you just have the fridge be a little bit off the ground and cut out a plug of foam? That way, when you want to drain it you just pop the plug, but it should still retain good insulative value while in place.
 
Rufus Laggren
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Adam

That sounds plausible. You need to seal the insides of the hole to be completely waterproof and design at the "plug" to seal completely at both the inner and outer surface (to maximize insulation); and also, of course, to always stay in when it's installed and then to come out easily when you want to remove it. Some method of contain spillage when your remove the plug would also be important - the plug might well be in a somewhat less accessible location.

I haven't looked at designing these things in over 10 years, so I'm not really the one to give advice. If I were going to make one I'd just spend a month or so plowing through boating how-to and project sites and following all the links. Because of their space and power usage constraints (on small sailing vessels) boat systems can be a tough design challenge. Having more space would make the whole thing easier and probably cheaper but the principles would be the same.

IIRC the hardest build issue for a high performance box is sealing the door/hatch. It requires multiple seals (at least two, one at the inner surface, another at the outer surface) which all must seal completely when the door/hatch is closed. That's how you maintain the highest effective insulating value and reduce the power requirement. Of course usage habits bear just as heavily, since filling the box and opening it only once or twice a day will greatly reduce your heat gain compared to grabbing beers every 15 minutes and browsing the left-over containers for 5 minutes at a time.


Rufus
 
Creighton Samuiels
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I know this is an old thread, but...

R Scott wrote:
You want the blocks to be almost cubes--as thick as possible and just enough taper they will come out of the mold. I have done it using dishpans as molds for one or two, but they will not last. I haven found a cheap easy mold idea. The amish made theirs out of metal so they could bang them around and not worry about the mold breaking.


If you're not Amish, then clean 2 liter soda bottles, filled with tap water or a salt water mixture and an inch of air at the top, work great.
 
Allen Herod
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it is old, and i didnt read all the replies... did anyone ever mention dry ice?
 
Creighton Samuiels
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Allen Herod wrote:it is old, and i didnt read all the replies... did anyone ever mention dry ice?


No, but dry ice is almost exclusively an industrial product. Hard to find it out in the woods. Around here, a lot of people talk about how useful dry ice is for keeping the regular AC refrig cold during power outages. Sure, if you're one of the people who bought some before the power failed. Because, 1) the cash registers will not work during a power outage, so the store is closed and 2) anyone with experience in such matters already bought all the dry ice that was available before you could get there.
 
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