Heat source for lacto-fermentation

I'm looking for a small and efficient heat source so that I can use a camping cooler for making yogurt and other lacto-fermented stuff. In my last apartment I had a gas oven that maintained 105°F all by itself, because of the pilot light. But I just moved, and the appliances here are electric.

For now I am using a cooler with a light bulb inside, but of course that is not cost effective. Can anyone recommend some kind of cheap device that I could put in the cooler to keep it around 105°F? Thanks for your help.


Byron

compost heap?

For lacto-fermentated vegetables (cucumbers, green tomatoes, red tomatoand pepper and onion relishes I ferment on an open shelf in my kitchen in lidded quart glass jars (using whey, following recipes from "Nourishing Traitions"). The temperature varies from seventies to eighties depending on the outside temperature, but I have consistant success. I also cover the jars with a dark cloth to keep out the light.
I haven't made yogurt for years but we did not have electricity then and it seems like I remember heating water on the woodstove to put in insulated box, we didn't make much yogurt just drank a lot of goats milk.
I incubate tempeh in my oven with the forty watt oven light on and sometimes add a kettle or two (in the winter) of hot water to reach a steady 85 to 95 degree temperature.

This person makes yogurt in a haybox cooker: http://www.meadows.pair.com/hayboxcooker.html

Do you have forced air heating? I used an old cabinet with no bottom and space around the shelves inside, placing it over a heater vent. I covered my jars with two very think heavy towels as they sat on a middle shelf in the cabinet. All my ferments turned out great.

In my next house I won't have central heating and so I'm considering using a timer on the base of my dehydrator and putting that under the shelves. This won't be second use, so I'm still thinking about it. I wish there was a tail-pipe for the heat coming from my refrigerator I'd run that in there. I still really like the shelves in an inclosed cabinet as a fermenting locker. I suppose using a light bulb inside is another opinion. Or building a fermenting box on the side of a stove/oven with the area against the stove having no cover.

A lot of the battle in keeping a steady temp is by stopping drafts and such, so enclosing and covering is a big part of it.

Interesting idea, but unfortunately I just have space heaters here in southern California. I've thought about the refrigerator too, and also the possibility of putting warm electronics in the cooler, since there is enough space at the lid handle for wires to get out. But so far nothing is quite working, either because the heat output is not consistent, or because it's too difficult to route the warm air.

A fish tank warmer would be perfect except that they only go to about 90°. The light bulb works, but of course they burn out after a while, and it's not the most efficient way to generate heat. Maybe a countertop "5th burner" would work, but I'm thinking it might not have a low enough setting. Well, I'll be interested to know what you come up with for your new place.

I've heard people have had success with aquarium heaters.

Neal, do you by chance know if the aquarium heaters work for fermenting at 100°+? I'm also wondering if it's necessary to put the heater in water. I suppose it would be easy enough, though simpler not to.

Byron

What about a solar oven? Course it may get too hot unless you keep it aerated some. How long a period do you need?

Well, solar might work if I had some kind of material that would absorb heat during the day and release it at night. For "sour juice" I usually ferment 30 days, so it does need to be fairly stable. Seems like there must be materials that would work, but I have no idea how to find out about them.

Byron, when I make yogurt, I put water that is at the right temperature in a camping cooler. The water will stay at the correct temperature long enough for the yogurt to incubate properly.

Have a look at this page, the author describes in details his method, which involves a cooler and water.

Thanks Adrien, though I make a different kind of yogurt that takes 48 hours in the box. It's more like a smooth cheese. So I will need a steady heat source of some kind.

I'm wondering how warm the cooler will be if it contains a large jar of water that is kept at 95° by an electric heater. Maybe someone on a science forum will know how the heat transfer will balance out...

Over time it will tend to go to 95 F.