Make a Dehydrator From a Dorm Fridge




How to make a food/fruit dryer from a dorm fridge using recycled materials.
Material list:
-dorm/bar fridge
-base from slow cooker/crock pot (found at dump)
-110V fan (though a 12V should work as well but then you'd need a power supply as well)
-thermostat assembly from an electric stove (found at dump) (save all the screws you take out to get the back of the stove and use them to mount the shelves etc.)
-neon indicator lights from same stove
-racks/shelves from old stove/fridge
-piece of aluminum angle cut into +/- 1" pieces for rack hangers
-on/off switch (a regular house light switch would work as well, but not as cool..)
-misc. wire, crimp terminals and wire nuts and misc. fasteners
-Mylar sheet/aluminum foil
-aluminum tape, duct tape
-screen material to cover vents and lay on racks
-And of course, some fruit to dry

Tool list
-wire strippers/crimpers
-drill, bits, holesaw
-utility knife
-And most important, basic common sense and the humility to ask for advice when needed.

Step 1: Remove Freezer and Controls

Remove the freezer compartment and controls from the inside and the compressor etc. from the back. Keep the fridge power cord for the new set-up.
Cut around the door shelf to remove it and using a fishing wire leader or piano wire or a guitar string slipped in through the cut at the top, saw downward and cut the foam and remove door shelves.

Step 2: Install On/off Switch and Indicator Light

I used a DPST (double pole single throw) switch so I could turn 2 things on at the same time. I have the indicator light come on with both devices (fan & heater) but I think I'll rewire it to come on with the heater as I can hear the fan, but am not sure when the heater goes on and off.
I cut the inner plastic skin of the fridge with a knife, cut the foam with the hole saw then drilled the metal shell for the switch and the indicator light.
The switch is held in by a nut on it's shaft, the light clicks on to the inside of the indicator lens.
After mounting the switch etc. drilling through the foam from the back for the wires, I covered the switch back up and sealed the cut with some aluminum tape.
The wires run down to the base in back in a groove cut in the foam.
I covered the vent holes with some copper screen I had then duct taped the cover back on the foam on the back.

Step 3: Install Fan and Heating Element

Using the hole left behind from the freezer cooling tube, feed the wiring out to the back of the fridge. With the hole saw drill (2) vent holes in through the plastic skin of the interior and the foam insulation. I left the freezer hangers to mount the thermostat probe.

Step 4: Wiring in Fan and Heater

I used the enclosure from the fridge controls to mount the oven thermostat. The center terminal is power in, the side one/s are power out to the heater. Power from the main power cord goes up to the switch then comes back down and is plugged into the center terminal. There is another side terminal on the bottom (not visible) and I plan to wire the indicator light to that so that I know when the heater is on. It looks more complicated than it is.
The wiring goes like this:
-the white from the power cord is wire nutted to the white of the fan, one wire from the heater, and to the indicator light.
-the black from the cord is tied into the wire to the switch which comes back down and (1) wire goes to the center terminal of the thermostat, the other switched wire goes to the black on the fan.
-the green/ground wire is re-attached to the base of the fridge.
I drilled a hole in the edge of the cabinet and zip tied the wires to make it all neater.

Step 5: The Finished Product!

I cut some aluminum angle I had to make hangers for the additional shelves which were from the stove I got the thermostat from (cut smaller). I put washed fiberglass screen on the shelves for the fruit.
I covered the door with some sticky back Mylar sheet I had around (doesn't everyone?), though I suppose one could use tin foil. After the test run, the heat had unstuck the sheet, so I'm glad I'd cut it big enough to tuck under the door seal. At some point I'll have to tack it down with something: stainless, aluminum or plastic as it is quite humid in there!
My first load was guava and pineapple, the second was bananas and the third shown here was pineapple and bananas. YUM!
I need to do some more R & D. I may add a second fan to vent the moist air, though I'd hate to lose the heat as well....I may use PVC pipe and run it back down to the lower vent hole with a Tee so that the warm air is drawn back in but the moisture which has condensed will drip out (not on the wiring, tho' !)



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      27 Discussions


      5 years ago on Step 4

      what can i use as a heating element instead of the crock pot element?
      can you please suggest other heating devices please
      (not necessary recycled ones)

      3 replies

      Reply 1 year ago

      A 100 watt light bulb mounted in a ceramic light bulb socket will get you to 110 degrees.


      Reply 5 years ago on Step 4

      Aloha~ I have built a second unit using the heater/ blower assembly out of a dishwasher. This combines the two functions and I still have them on separate switches with the heater on a thermostat.

      You could use a small hot plate food cooker but would still need to wire it into the thermostat so it would shut off the heat periodically but not the fan.

      Hope this helps. Until later, be well. Jamil


      Reply 4 years ago on Introduction

      Since you should be running this so the temp is no more than 115 F/45C you can use just about any heating element.


      5 years ago

      Great help to domestic Food preservation and benefiting


      6 years ago on Introduction

      Cool. But it would be interesting to make one that uses the power of the sun. There must be a way and would safe money on elecricity. Something similar to a solar oven. Maybe painting the refrigerator in black


      Just what I was looking for. I've got an old intergrated fridge that's a bit tired and unwanted.
      I intend to remove all the electrics, compressor etc. and install a 12v system comprising two 12v automotive lamps, a fan and a thermostat. I can then hopefully use this as a drying Jerky/Biltongbox.
      I'm also considering adding an inlet pipe to connect an external smoke box to make this also useful as a cold smoker.


      10 years ago on Introduction

      Good work, good idea. I have in the garage a fridge of approx. 60-70 years age. But it still functions...

      4 replies

      Reply 10 years ago on Introduction

      That's the great thing about older machinery, lower build tolerances and design for use in rougher environments than they design for today mean the machines had to be servicable and tough enough to stand up to punishment. If you kept them in good shape though they could run for a super long time.


      Reply 10 years ago on Introduction

      Here in Argentina, Christmas is full summer, and then that old fridge shows what is worth. We fill it with bottles of soda because the main fridge is busy with other meals. I think that it can last other 20 or 30 years, taking care of it a little. Nevertheless, it is easy to obtain old fridges that do not function. In fact, many people takes advantage of them to do carts, applying them a motorcycle wheels pair.


      Reply 7 years ago on Introduction

      Good idea, old frig for parts. My uncle had a refrigerator door mounted on his basement wall with parts filling it.


      Reply 10 years ago on Introduction

      I'm a big fan of re-purposing old things. I wish my own countrymen were as quick and creative to reuse something as they often can be to just go buy a new whatever they need. My home's fridge is much younger (only a little younger than I am) but in it's 18-19 years it's had minor repairs and maintenance that would have many people I've met simply give up on it and toss it out for a newer model. It seems they have to do this faster and faster each time as build quality goes down and people's willingness to treat things as disposable goes up. Very sad. Here's to hoping both of our fridges keep kicking for years to come.


      7 years ago on Step 5

      Most dehys have a vent of some sort to let the moisture out, the importance of the fan is to circulate the warm air - if it's cooling off the food, it's too powerful, it's just to keep the air circulating.

      The moist air is actually bad for the process too - even 'finished' foods from this set up might grow mold if not eaten quickly after processed, due to the moisture.

      A good way to do meats is to marinade/dehy at 140/155 F for several hours (dependent on the meat) then put into a preheated oven (275F) for 10 minutes, and then let cool to room temp. This dries your meats (jerky, etc) and then makes sure the internal temperature reaches 160F to kill any bacteria that could harm you later - as well as "finishes off" any lingering moisture.


      Reply 10 years ago on Introduction

      I don't think so, because since it takes 24 hours to dry some pieces of pineapple, beef jerky would take ages, therefore rotting. I may be wrong though...


      Reply 9 years ago on Introduction

      I make my own beef jerky using a box fan and an air conditioner filter. Works amazing