Intro: Make a Dehydrator From a Dorm Fridge
How to make a food/fruit dryer from a dorm fridge using recycled materials.
-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
-drill, bits, holesaw
-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' !)