food dehydrator

okay, every year i tell myself i'm going to make a food dehydrator.

I liked the bullock's set-up, pic below. But the darn thing doesn't work so well on cloudy days. And Orcas gets more sun then I do.

In lieu of that I think I can rig together something with an incandescent light-bulb, a small fan, and a big cardboard box. Before I begin this crazy expedition are there other ideas?

I'd love to be able to tap the heat of a propane fridge, like Sam and Yuriko Bullock do. But no propane here. hmmmmm....

Believe it or not, I've done the cardboard box food dehydrator before. Worked out beautifully! When I first started, I was using a 60 watt bulb, and it just wasn't enough heat for the size of the box, so make sure you up your wattage. And since the key is heat, don't bother using a CFL or LED - just go for the incandescent. Use an oven thermometer to figure out how hot it is in the box.

Another tip is to figure out how to insulate the box. It breaths a bit too much, so you'll need to line it with something. Some foam-core would probably be best. I've seen it done with aluminum foil, but I worry about all of that heat conducting into the cardboard directly. Might be a bit of a fire hazard. If it gets hotter in the box than you'd like, prop the top open and poke a few holes in the box. WIth 100W bulb, I usually saw temperatures around 200F, 180ish with the top open.

It is a lot of energy used to dry food though. It would definitely be great if you could find another more-passive heat source. It's too bad it's so cloudy around here this time of year...

holy crap! that's so cool you've done it before, because i was wondering if i was crazy for even considering it. ha!

that's great you even have info on bulb wattage and heat. i'd thought about incandescent, but not much further beyond that.

for insulation, do you think i could just throw a blanket over the box? or if that's too much then a couple sheets?

what's your instinct say about the fire hazard from all this?

(i was thinking if the housemates aren't too keen on it i could always do it outside, but that becomes Way too much electricity!) I also found a source today that said even a fan with no heat could do it. I assume the batch would take longer to dry though.

Yeah, I would be pretty careful. The cardboard can definitely catch fire if it gets too hot in the box. In the early stages, we had one box get a hot spot that smoldered a bit (turned black and generated some smoke). It was because the way we had rigged the light bulb slipped and the hot light fell against the side of the box. Could have burned out entire place down, but luckily I was home at the time.

My tips to lower fire risk:
1. make sure the light isn't touching ANYTHING!
2. line the insides of your box with material that is fire-resistant and non-conductive.
3. monitor your temperature. this is the key. you need to make sure it doesn't spike in any place in the box. if it's consistent, you should be okay.
4. do it outside. it's a good idea.

I don't know about throwing a blanket on the box. That sounds to me like an accident waiting to happen...

Fan might not be a bad idea. It would take longer, but would definitely work. It would also take more energy. Typical fan runs at about 60W, so if it took a week, it's using about 6x the energy your incandescent would over 18 hours. Still, completely eliminates the fire hazard.

Another safer option might be to just use your oven. Turn it to its lowest temperature, crack the lid, and let your fruits and veggies stew for a day. I've done this too, and the results weren't significantly different.

Good luck! And be careful!!!

just an update:
with only nettles to dehydrate thus far in the season, MJ is right, really no need to construct a dehydrator (yet). I've been happy with either oven cracked on low (170 degrees) taking about 3 hours. Or cheesecloth/fabric 'shelves' in dark room taking a couple days to dry the nettles.

So, not much exciting to report for now. When it comes around time for plums or something, that's when the real dehydration fun will begin because I won't be so happy with these two options. More later....

What about drying stuff on or near a woodstove?

What's the best way to dry foodstuffs to preserve the most nutrients?

The woodstove idea: I'd do it if I had one going.

The bullocks' had a set-up in their old cookhouse (now torn down) with a dehydrator cabinet on the wall near the woodstove, probably some flashing on the side so wouldn't get too hot, but maybe also flashing that led the heat from the woodstove to the 'bottom' of the cabinet, which was just wire mesh.

The heat would be guided by the flashing up and through the cabinet.

The downside was that it's so seasonal, and at least in that place, inconsistent. (The woodstove was only lit at night).

This year at Doug and Maria's house they hung a couple old spoked bike rims from the ceiling near the wood stove and hung small buncles of nettles from them. They looked like nettle mobiles and worked like a charm.

I just hung a line across my cabin near the wood stove and managed to dry mine in a few days. The only caution I'd have is not to get overzealous with the size of each bundle of nettles because the centers could have trouble drying.

Dave

It's a little late for the PNW, but....

In the summer time, what is the hottest thing you climb into?

A closed-up car facing the sun, right?

A guy in Oregon in the 80s (think 'lumber industry crash') had an old car sitting in his yard (no engine or tranny), and he started to look at it in a whole new way.

He turned it around by dragging it with his riding lawn mower so the windshield faced the sun (south).  He removed the seats and steering wheel.  He set some of those two-hole concrete bricks on end on the floor and laid boards across them.

Then he laid some of his fruits and veggies on cookie sheets and scavenged cafeteria trays and set them on the boards.  He closed all the doors and just rolled down the windows about a half-inch each for moisture to escape.

It worked great, he didn't have to panic if it suddenly rained, no animals could get into it, and it required no electricity.

I thought it was brilliant.  But my only old car is the one I'm still driving... 

Sue