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Freezer to fridge conversion?  RSS feed

 
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Has anyone built their own fridge out of an old chest freezer that was more efficient and  cheaper than a Sundanzer? (for example)

I'm thinking of doing the "old freezer to fridge conversion" I've seen online to be used in the tropics, but I'm thinking of taking it a couple steps further.
1. Cut the freezer in half horizontally.
    - the normal depth of a chest freezer isn't practical for daily use. I'm thinking if it were half as deep, it
      would require less electricity and provide easier access to what's inside.
    - so I would take a skill saw to it all around to cut it down to size then reattach the lid?
2. Increase or even double the insulation.
    - I always wondered why there aren't manufacturers out there who haven't done this?
    - I would remove the outer shell of the chest freezer and just double the thickness of the insulation (especially on the bottom and side walls) to increase the r value and again reduce energy consumption.

It would ultimately be used in the Philippines on a solar system.
Any thoughts? Has it been done before?
 
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Yes. The thermostat has an adjustment screw. I was lucky enough that I could turn it far enough to make it a fridge.
On this model cutting it in half would not (easily) work, as there are cooling pipes on the inside and heat radiating pipes (condenser) on the outside.

Instead a two boxes could be used. One for the less used things below and one for the common things above.
Energy use is not much of a problem. It uses 75W when running, but does not run often. (I have to measure it).
 
steward
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to reiterate Sebastian's point about the condenser: at least on the models I'm familiar with, adding more insulation would actually dramatically reduce efficiency. the condenser is placed under the outer skin of the freezer so the whole surface acts to radiate heat away. if you add insulation over that, the heat will not be radiated away and the compression cycle won't be able to cool the freezer.

for more insulation to work, it would have to be placed toward the inside of the freezer from the condenser tubes, which would not be a trivial undertaking, to put it mildly.
 
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Is there any reason why you can't add the insulation inside the freezer instead of cutting the unit down and then adding insulation to the outside? I'm thinking about the practice of storing gallons of frozen water in freezers as I say this.
 
tel jetson
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yeah, Casie. for the same reason it won't work on the outside, it won't work on the inside: instead of condenser tubes, there are evaporator tubes under the skin on the inside. insulation there would just keep energy from traveling out of the freezer box, which is how it's cooled. any additional insulation would have to go between the evaporator and condenser tubes, at which point you're probably better off starting from scratch.
 
Casie Becker
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So now I'm curious about whether the old technique with the water gallons even works. We've never had an empty enough freezer to try it ourselves.
 
tel jetson
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adding water isn't about insulation, it's about adding mass. you're making a sort of thermal flywheel so that the compressor doesn't cycle as frequently. it might run a little longer when it does cycle on, but it should work out to be a bit more efficient that way and last a little longer. the beginning of a compressor cycle is when the bulk of wear on the moving parts takes place, so if there are fewer cycles, there's less wear.
 
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New chest freezers are cheap,so cheap they rival used refrigerators on a cubic foot basis.
As far as hard to access space, filling the bottom with one gallon jars of lacto fermented foods seems ideal.
Buy a second freezer for more space, repeat with the gallon jars.
I would add a  tempature controller .
For about 20 bucks, it will hold the temp at 40.
It has a tempature probe and a place to plug in the appliance,no fancy wiring needed.

Now that I'm thinking about it, I should order one for my ancient huge basement upright freezer, and buy a 5 cubic foot chest freezer for upstairs.

Clearly chest freezers are more efficient, but an upright freezer converted to a fridge is probably more efficient than a standard refigerator.
I could fill it with ferments,out of the way of my family's everyday fridge use.

The same temp could controllers might be useful for sous vide and smoking.

 
Sebastian Köln
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About the water trick… Before converting it to a fridge, it was filled with water bottles which were then frozen (and some exploded…).
While freezing took 3 days, the result was ice/cool water for the the 7 days of travel under rather warm conditions.

If you can find someone who repairs fridges/freezers, you could build your own from spare parts. I don't like the idea of cutting into the coolant pipes…
 
tel jetson
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William Bronson wrote:Clearly chest freezers are more efficient, but an upright freezer converted to a fridge is probably more efficient than a standard refrigerator.



I'm not sure this is true. chest freezers are more efficient primarily because of the orientation of the door, not because they're freezers. the heat pump apparatus is optimized for freezer temperatures, not refrigerator temperatures. so I would guess that an upright freezer would be slightly less efficient than the same size upright refrigerator.

one advantage of most upright freezers and refrigerators is that the condenser tubes aren't usually in the skin, they're on the back or bottom. if that's the case, you could actually add insulation to the outside as long as you didn't restrict airflow past those tubes. my guess is that a chest freezer conversion would still come out ahead, but that might depend on how often you'll be opening the thing. the more it's opened, the better the chest option looks.
 
William Bronson
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You might be right, but the extra insulation alone might make the difference.
Here is one source that claims as much, though the method seems more involved:
Convert a Freezer into a High Efficiency Fridge
 
Dany Richard
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Thanks everyone for your time, the education and contributions to the discussion!
I now understand that the condenser tubes make my idea impossible.

Here's a follow up question. I can't find anyone online that has ever built there own chest type fridge (plywood shell, a ridiculously high R value walls, salvaged condenser tubes, etc) with components from an old freezer.
I'm not asking if it's worth the effort, but only if it's possible just to see how far we can take the energy efficiency?
 
tel jetson
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I do think it's possible. to get it right, you might need coils from two different freezers: a bigger one for the condenser coil and a smaller one for the evaporator so that you can have thicker walls and more insulation. the alternative would be to re-bend one set of coils to fit the new arrangement, which would also be difficult.

some things to consider:
  • most refrigerants are potent greenhouse gases. beyond that, I don't know much about them chemically. they may be horribly toxic, or they may be inert. but if you lose any, and you most likely would, you would very probably be creating more problems than you're solving, at least on any scales bigger than your immediate financial savings.
  • fitting coils together without leaks is not easy if you haven't done it before.
  • and the compressor that you get out of one of the old freezers may not be tuned as well to the new arrangement and you may, again, lose efficiency there. I don't know that you would, but you might.
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    Dany Richard wrote:Here's a follow up question. I can't find anyone online that has ever built there own chest type fridge (plywood shell, a ridiculously high R value walls, salvaged condenser tubes, etc) with components from an old freezer.
    I'm not asking if it's worth the effort, but only if it's possible just to see how far we can take the energy efficiency?



    I have a thought, but lack knowledge. That is to say: this may not be a good idea, but it is an idea. Maybe some good could come from the discussion of it. How about the home made shell you describe, with a coolbot and a small and efficient air conditioner?
     
    Sebastian Köln
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    It is possible to get affordable compressor for solar/DC usage (low starting current), where as DC/off-grid fridges are usually quite expensive. Building your own might save quite a bit. (And even allow to turn an entire cellar into a fridge/freezer!)
     
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