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DIY Frdge freezer

 
Posts: 484
Location: Englehart, Ontario, Canada
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Living way the heck up north it is winter, as in below freezing, from 5-6 months a year. I'd like to tap into that. I'd like to convert some corner cupboards on an outside wall to a built in fridge freezer that can use either normal refrigeration technology or when cold enough a fan and outside air. I figure between superinsulating and using the exterior air temperature I could reduce energy use to about 25% of current levels. Anyone know refrigeration well enough to comment on the technical aspects?
 
                    
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Location: AR ~ozark mountain range~zone7a
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I was lucky enough to spend a week in a motel at Wisconsin one February, the deep set window ledge was nearly a foot deep, and nicely covered with a very heavy drapery. The window was the type that slides open to the side, by merely leaving the window slightly open, and the drapery clothes pinned together, the window ledge provide a nice well ventilated cold spot for food & beverage, not a true 'freezer' but adequate fridge.

Also you can put frozen ice bottles in your fridge or freezer, replace daily if necessary...that saves a few bucks, if you take time to do it.

It might be possible to cut a hole in your fridge (NOT the freezer part, but the fridge part), attach a metal duct pipe or clothes dryer vent pipe to the hole, route it to the outside, put a small fan (that won't blow the fridge door seals open) & ON-OFF switch with a indicator light...to indicate when the thing is ON. It might help circulation inside the box, if there is a smaller 1" plastic pipe within or nearby the metal duct pipe, have the 1" pipe extend into the box to pickup stale air in the box and route it outside.

There are various insulation/reflective readily available materials, plastic wrap (to easily bind fiberglass wrap), fiberglass, used stryofoam cups, styrofoam board, aluminum foil, aluminum-ized paper, cardboards, bubblewrap, automotive carpet padding, polyester blanket.

Outside air will probably give you much more moisture inside the box, than your presently accumulating, the bad thing about that is that most refrigerators use heating elements beside the evaporator coils, and often around the door seals there is another heating element, they are setup to drive off moisture with a heating element, which uses alot of electricity. If you can do it safely you might look for some kind of product that 'absorbs moisture', but there should never be poisonous substances IN THE FOOD BOX!

james beam

 
steward
Posts: 2524
Location: FL
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Growing up in Bangor ME, I can tell you from experience that using the great outdoors for a freezer works just fine. When those turkeys go on sale after the holidays, grab a couple up, keep them on the porch.
There are some problems to watch out for.

-Animals
Outdoor food storage absolutely must be kept in an animal proof container. Dogs, bear, racoons, skunks, animals large and small, brutes and dextrous.

-Thaw
Towards spring, days get warmer. When the daytime temps get above freezing, your food can thaw out just a bit. When it freezes again at night, ice crystals will form in the thawed areas. The result is freezer burn and destroyed food. If the foods will handle repeated freeze/thaw cycles you'll be fine, but the selection is somewhat limited to tomato sauce and berries.

I did the math on producing ice for an ice house. With the brutal cold winters, ice can be produced in massive volume. Enough to operate an ice house all year. There is labor involved, it's not as convenient as plugging in a fridge. Options for production are cutting it from surface water or filling molds in the back yard. If cutting from a lake or pond, there are safety issues and the ice must be transported back to the ice house. Molds can be as simple as 5 gallon buckets. Set these in a tub of warm water to release the ice. This will run up your water bill if using your plumbing for a water source, but you can repeat the process daily, put up a huge amount of ice.

 
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Rather than just using bottles of frozen water you will find a mix of 15% sawdust and water stays frozen longer. The material is called pykrete and is more akin to concrete.
 
Posts: 59
Location: Southern MN
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Nice to hear others want to reduce freezer/refrig energy. It has been one of the biggest obstacles in our sustainable home n farm design.

I agree that popping a hutch or old refrig/freezer unit through a north wall would cut electrical on it at least a good part of the year.

Then, add to the system-
Get some broken freezers. 2 should do it for an average home needs up north and more if you are more southern. Maybe add some extra insulation for good measure. Then fill the freezer with old milk jugs full of water and then freezer those over winter by leaving the top open on the coldest nights and close up day time to keep it as cold as possible.

Then, as needed, use a milk jug or 3 in the hutch outfitted refrig/freezer. I don't think it would ever get cold enough to freeze anything, but maybe one of the frozen recycled freezers would hold some ice cream, but I wouldn't tax the stored ice until you know it's capabilities.

Thanks for posting a good topic!
 
Max Kennedy
Posts: 484
Location: Englehart, Ontario, Canada
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Thanks for the feedback, the idea's are great and with my unheated sunroom already use most of them in some way. Temperatures during the day have been -13C (9F) and -25C (-13F) during the nights, not worried about thawing. However what I am really looking for is to make a home built super-insulated electric fridge that I can run pipes with fans to the outside so as to be able to use exterior temperatures for much of the year but still have regular refrigeration during the warm weather. I'm not looking to modify a store bought fridge though the compressor, cooling coils and controls can be scavenged from one. It's either the scavenging from a store bought fridge or what components I would have to buy that I am looking for help with.
 
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Why don't you just put things outside?
 
Max Kennedy
Posts: 484
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Dave Quinn wrote:Why don't you just put things outside?



Because many things are in the fridge, not the freezer and at -20C it would be very difficult to use the ketchup, mustard etc. Also I try not to feed the wildlife but myself.
 
Posts: 95
Location: NW Montana
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I want to do this too. Read this link for inspiration. Basically circulate outside air through your fridge, insulated box, or whatever. If you get fancy you can use a thermostat to control the fan. Edit: and you don't need to know about refrigeration, just how to hook up a fan.

 
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Location: victor idaho, the west side of the tetons
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i just keep my fridge in the shop for the winter to protect food from freezing and critters.

for the ice house discusion. i'm keeping my eye's out for old used, cheep, maybe free walkin cooler panels. if i assemble on the north side where all my snow sheds from the roof and direct it into the 4 panels. stomp on it and run water on it occasionally through the winter. make one big ice block with a fridge in the middle it could last until mid july. its ben 10below for a couple of weeks. ice block making weather.

for those in the cold north. if you take a radiator for a small car (soobie,honda, ect) connect 3/4 pex to it. insulate the lines and run a surpentine pattern in you fridge with a swamp cooler pump( super low watt), lines filled with 80/20 glycol water mix your fridge will stay cold. if you bury it about 4 ft down in the summer it will keep your fridge from cycling most of the time.

just some thoughts to keep you tinkering through the winter

cheers gordo
 
gardener
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Not far from where I live there are a few caves (lava tubes, actually) that are filled with ice year-round and it always makes me wonder: Could I make my own artificial ice cave?

Seems to me there's a couple of key features to caves that hold ice:

The surrounding stone is a decent insulator due to the many gas pockets trapped as the lava cooled.

The cave has to hold and collect water.

There has to be sufficient air flow.

With these things in mind I don't think that it would be too difficult to reproduce as long as you're in an area that gets cold enough in the winter. I'm imagining digging a deep trench, deep enough to walk in with 4-5 ft. of ice in the bottom, then lining the whole thing with good insulation. Make a solar chimney to help create a good draft with an air intake placed to maximize pulling cold air. Put some cellar doors on one end for easy access and a metal grate where you want the floor. I think one of the hardest part (or should I say most site specific) would be figuring out a way to channel runoff and melt-water into the bottom of the trench.

As mentioned above, you can add sawdust layers to the ice and it will last much longer.
 
pollinator
Posts: 3738
Location: Vermont, off grid for 24 years!
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Max Kennedy wrote:

Dave Quinn wrote:Why don't you just put things outside?



Because many things are in the fridge, not the freezer and at -20C it would be very difficult to use the ketchup, mustard etc. Also I try not to feed the wildlife but myself.



I put food in a cooler in my mudroom. Keeps the animals out and doesn't freeze. The mud room is on the north side of the house and for the last 2-3 months the temp in the cooler has stayed remarkably constant. Colder than my 12v fridge inside.

I used to have a link to a fridge where the guy made a (backless) fridge in front of a outside door and I think he cut a whole in the door (or made a temp door) and had a 12V computer type fan to draw in cold air/pull out warm air. The fan may have been activated by temperature. Sorry, can't find the link.
 
pollinator
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Location: Chicago/San Francisco
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The pleasure boating world has striven for 12 to 48 volt low-energy compact refrigeration for a long time. If you can find books by Nigel Calder at the library or elsewhere you'll have extensive and explicit explanations and design considerations, rules of thumb, etc, covering both the cooling units and the boxes. Probably many other good tech writers out there; he's the one I found most detailed while being understandable.

From what I've read, your basic idea to use outside cold to freeze and refrigerate is perfectly doable with a few electronic controls for small fans - while it's very cold out. When it rises above 0F then it gets funky because you want your freezer to stay about 0F and that means you must:

1) Start the "backup cooling" automatically when outside temps rise to a certain point; to maintain freezer and refrig temps it needs to incorporate all the standard controls and probably a few extra. This "backup cooling" can be what you run all summer.

2) This is the hard one: The "outdoor coolant" connection needs to be closed and totally insulated or it will be just a huge heat leak into your freezer (the refrig can be cooled by the freezer if they're part of the same construction). This applies even if the temps outside are 10 D below freezing (ie. 20F) because that's a heat wave relative to the temps you want inside the freezer. Unless the outside air passage is shut and insulated it's going to load up your system with heat when the temps rise above 0F. For this reason the idea above about using a heat exchanger (from a car part) instead of direct air cooling is likely the best way to go. It's way easier to insulate a few tubing penetrations, close a solenoid valve (to keep coolant from circulating due to thermal gradient) than to deal with an air passage which, if you can insulate it successfully, will almost certainly require timely manual intervention several times a year. But you end up with two separate mechanical systems which is more complexity and not ideal.

It may be more practical and effective to not try to actually cool the unit directly with outside temperatures but to just locate the box to use outside temps to passively reduce the heat load as much as possible. Design the box for true "super insulation" and then cool the thing using the most efficient compressor, fans and cold plate system your can assemble. The refrig section must be connected to but insulated from the freezer and cooled from it with a ducted fan. The mechanicals can be modified/repaired later relatively easily if the box is designed with that possibility in mind.

Of course, this uses electronic technology and almost certainly foam insulation along with best quality door seals. If that's not part of your philosophy than "ice house" technology may be more appropriate but it won't provide long term frozen storage. Once outside temps rise above 0F you're above ideal and once they get above 20F thaw is just around the corner. The large margins are because temperatures change quickly due to outside temps but also particularly to heat load when you access your freezer/refrig. Also because it's Not Good for frozen food to surface thaw and then refreeze you want it quite cold (0F) to begin with. Besides messing up the structure and taste of the food, surface thawing can cause spoilage that may not be readily detected and that's not healthy.

One reason ice _warehouses_ could keep things (ice) frozen so long was because the cold space was quite huge and the contents massed together. Home freezer/refrig usage requires that the access door/hatch be very large compared to the storage area and that the actual contents be accessed randomly (ie. you want to be able to get what you put on the back or bottom shelf, not just what's in front) and the contents are not shaped so as to pack together tightly and maintain their temp best. The heat load of home usage is very large per unit volume compared with that of an ice warehouse and this makes simple ice cooling problematic for keeping things frozen at all when the temperature at the access is above freezing.

Rufus

 
Cj Sloane
pollinator
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r john wrote:Rather than just using bottles of frozen water you will find a mix of 15% sawdust and water stays frozen longer. The material is called pykrete and is more akin to concrete.



More info Pykrete

Once the January thaw is over, maybe I can do some experiments!
 
Max Kennedy
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Thanks for that pointer Rufus. Will look into that.
 
Posts: 407
Location: Fairbanks, Alaska
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I framed off a corner of my dirt floor basement and insulated it from the rest of the house to use as a root cellar; it's vented to the outside and fitted with thermostats to regulate the temp by blowing cold air in during winter (or warm air from inside should it get too low during an extended cold snap). It's cold enough here that it could be a walk in freezer, but we can just stick stuff outside for that; since it's for root crops and sauerkraut crocks and such, we keep it around 34-35 degrees F. But it's great--basically a big walk in fridge. It solved our garden produce preservation issues, and is a real convenience and energy saver.
 
steward
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When I was in high school, many moons ago, my family lived 2 miles south of yellowstone park. We ran a campground and lived in a log cabin. Great times were those! I had an aquarium setting on a table next to a window and one night it got pretty cold. Next morning I noticed my aquarium was frozen solid, glass broken. So ya I bet a fridge would work !
 
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