My background as a farm girl and living where stored food was a necessity as well as my wish to find a way to dry my herbs led to both the invention of the Living Foods Dehydrator (the first electric food dehydrator) by my husband Bob, and the writing of "Dry It, You'll Like It" by me.
Along the way to inventing an electric dehydrator, we found many non-electric ways to dehydrate food. The basic principle of drying is the movement of warm air around the thing to be dried. Warm air rises naturally. (The heat-rising principle is Nature's most valuable contribution to the development of dehydrators.) Therefore, setting the food to be dried over a source of heat will do it. Be sure it is not too hot or the heat will cook the food instead of drying it, and destroy the enzymes. Temperatures between 80° and 120° F are the best. Also, make sure it is a gentle air flow not a huge wind.
In this article, we use the word "rack" to mean a framework on legs, and a "tray" as mesh screening stretched over a wooden frame.
I've put sheets over the furniture and dried herbs on them, just at room temperature.
I've taken herbs, and other leafy things, and tied them in clumps and hung them from the ceiling. Also, flowers can be dried this way. It's interesting to see flowers hanging upside down from the ceiling. The benefit of drying them this way is that the stems dry straight instead of flopped over as they would in a vase.
Some people put the herbs or flowers into mesh or cloth bags before hanging them from the ceiling. (Do not use plastic bags or any other type of bag that will block the air flow!)
In Medieval times, people dried apples by slicing them and then loosely stringing them on thread or cord.
The American Indians hung food from tree limbs to dry
It can't be repeated often enough: air flow is the basis of dehydration! So make sure the room you're using has good air flow.
My grandparents used a shed roof as a food dryer. My mother and her siblings took turns sitting on the roof with a huge fan to discourage flying insects.
Another source of the sun's warmth was my grandmother's attic. She had trays, racks and paper-covered floors to arrange the drying foods where they would dry the best. All this was very hard work but necessary for the long Kansas winters where trips to the grocery store were four months apart. Drying foods was an important way of life in those years preceding the 1900's.
One of our neighbors dried walnuts in the attic of her barn. So many attics have lots of heat but not much in the way of air flow. A fan helps, but a fan blowing air into an attic would blow dust onto the food, and also toughen it. A much better way is to have a fan pulling air out of the attic.
We found that dehydrator trays used in pairs will capture the sun's warmth. One tray is used as a screened lid with the food on the other tray. The two then are taped or clamped together. No bugs can have a free lunch and the foods dry safely. Bricks or stones can used to support the trays.
A friend in Oregon used a pile of rocks that were in full sun as a heat source. Her trays were window screens that she borrowed from their regular use and dutifully carried out and each morning to the rack she had built over her pile of rocks. She brought them in each night so that they would stay dry (dew falls at night) and so that the wild things wouldn't have a free meal.
A more modern use of the sun's heat is a sheet of black plastic about ten feet square spread out on the ground. The plastic becomes a solar collector for your dehydrator which stands in the middle of the plastic. For the best use of this method, be sure you have the type of dehydrator where the heat comes up from the bottom and goes out the top. Also, you need to turn the lid crossways so that air comes out of each corner.
In my teens, in the 1930's, we owned a farm of Filbert trees in Oregon, which is when I first saw things being dried. It is very important that nuts are dried if you want to keep them! The nuts were dried in a tumbler over heat. A tumbler could be turned by a hand crank and the heat provided by a wood fire.
American Indians dried food on a rock above a campfire. This is one of the ways they made pemmican.
One of our friends smoked meats to dry them in a smoke house.
We found that you need to use at least two ceiling hooks to hang your dehydrator over a wood stove. If hooks aren't possible, make or find a rack that will straddle the stove.
Drying food on a rack over a wood stove is a pioneer design. The National Geographic (June, 1917) has pictures showing food drying on racks over a wood stove. In this case, they don't have the dehydrator and the food is either directly on the racks, or on trays that are set on the racks. Another way we found to dry food is to pin them in bundles with clothes pins to a clothes line that is hung over the stove!
Or hang them from the ceiling here where it's warm! Garlic can be dried this way, or apple slices on strings or bundles of herbs.
My hot water heater was my first dryer. I took the insulation off the top of my hot water heater and put my drying tray over the top. This was a dependable heat source.
Coils of copper pipe or other flexible pipes can be built into a hot water heater for a dehydrator, much the same way as bottom-mounted heating unit is used. In one method, the hot water first goes through the hot water heater (which can be part of a wood stove), then under the dehydrator and then into the hot water tank.
One of my dryers was simply a tray on a rack over a propane heater. (Make sure that the propane heater is properly vented.)
Friends in Canada set their dryer over a steam radiator.
Setting a dryer over a heat register would work, too. You'll need a filter, such as an old towel or a piece of terry cloth, to keep the dust out of the dryer. Simply cover the register with the cloth and then wash the cloth frequently.
There are many, many ways to dry things without electricity. Look around, maybe you'll invent a new one! Just keep in mind that air movement is the secret of all drying for all items and you'll do well.