For my incubator, I used a small fridge that I knew I no longer needed as a refrigerator. It had been sitting around for about three years, and so, I was ready to upcycle it into something fantastic...
Here is the eerily lit Tempehcubator in it's temporary home.
You can also use a cheap, easily purchased, styrofoam cooler! Lay it down on its side, with the opening facing you, then the lid can become the "door" just like the fridge. Cut a hole in the back just like you see here with the fridge, and proceed. Or, come up with your own design, or hunt around for various designs that are around on the internet.
Most fridges apparently already have a hole (to release condensate) through which you can thread your thermostat wire without hassel, but alas, mine did not. So, to reveal a hole in the back of the fridge, I needed to remove all the hardware from the refrigerator part of the refrigerator. My dad helped with this! We removed a TON of stuff, basically a plastic grocery bag full of screws, plates, wires, the fan, etc. etc. I never got a picture of that bag of stuff (it's in my basement, I think), but here it is, the hole in back finally unadorned!
We were a little giddy when we finally got to look through the hole :-)
So, then we tried to wire a baseboard thermostat directly to the existing wiring of the refrigerator. We had stripped wires, and were trying to decode the fridge vs. thermostat wiring situation, but were tired and didn't feel like being clever anymore. Do you see ALL THOSE LITTLE HOLES in the back of the fridge? Well, each one had something attached to it and something attached to that, and we had removed all that stuff already :-)
Yeah, so, we gave up on wiring the baseboard heater and I ordered a plug-in thermostat on amazon.
Then, the holidays came, we went away, came back, and then I ordered my starter and had to wait for it.
Once I got my Powdered Tempeh Starter, I set to work at finishing the assembly of the incubator, so, back to work!
So, the wire that runs from the thermostat must fit out some kind of hole in the fridge. The hole in the back of my fridge was a pretty big square, so I had to make some adjustments to re-close the hole.
I covered the rest of the hole up with a piece of a brown paper grocery bag. I just used scotch tape on the inside of the fridge to tape it in there. I also simply used scotch tape to secure the thermostat in it's place. Easy. I used a three prong converter with the thermostat so I could plug it into a regular two-prong extension cord. The temperature probe (attached to the thermostat, sticks up from the top) should be on the inside of the fridge with the rest of the thermostat unit.
Anyway, so, here's the inside of the Tempehcubator again:
So, tape the paper bag over half the hole, stick thermostat on the other side and tape it (don't tape over the flap-door because you need to open that to set the temp). Don't worry about those wires (yellow & blue) near the thermostat, those were to the fridge and I didn't cut them off, they aren't live. Also, the fridge dial set to "4" isn't live, obviously, it was the fridge's. So, set up your lamp kit, cover the base with a simple piece of tinfoil and smash the tinfoil into a lamp base :-). I wanted to do that because it just fit a little better that way. Don't lay down the light bulb on the floor of the fridge without aluminum foil under it, IT WILL MELT THE PLASTIC ON THE BOTTOM OF YOUR FRIDGE :-) If you do want it to lie down, put some aluminum foil under and around it so it doesn't melt the plastic of the fridge. Anyway, so, I wanted it to stand up, so, that's what I did. If you have a metal shelf, you can put it on that.
I made removable shelves with chopsticks :-) I just measured the length I needed them to reach across into the shelving tracks, and then glued them together with a hot glue gun. It took two chopsticks, overlapped by about two inches, to reach across. You can also cut dowels to fit, but I didn't have any and I didn't feel like going to Home Depot. I placed the removable shelves around the lamp, and I was done with the set up.
Now, it's time to see if it works. Plug the lamp into the thermostat, and make sure the thermostat is plugged into the wall. Turn on the thermostat (switch for this one is on the right side) and turn on your lamp with its switch. Set the thermostat dial to "heat" and the digital setting to 88 degrees (or anywhere between 85 and 90 that you like) just by using the up arrow. Then, press the "hold" button. This seems to override the default heat setting (which will go down to 62 degrees from 10 pm to 6am, I found that out the hard way!). You can also fiddle with the time, and setting that if to correspond with the temp if you want, but I think pressing the "hold" button after setting the temp works to keep the temp at 88 for as long as you have the thing on. If not, I'll learn again the hard way next round :-)
If the air temperature is lower than 88 degrees (your thermostat will give you the reading for air temperature in your unit right next to your set temperature) then your light bulb should turn on within a few seconds to heat things up for a while until the temp reaches 88 degrees. Then the thermostat will tell your light bulb to turn off, it's hot enough. When the temp starts to go back down again, the thermostat will tell your light bulb to turn back on, and so on and so on, as long as you have the system turned on (which will be 20-30 hours for tempeh). After the first 12 hours, crack the door to allow some more air flow and to reduce the temp just a tiny bit (your tempeh will be producing its own heat at this point). Check your tempeh pretty frequently to see if it is done, plus it's really fun to watch it develop! My batch was done in 20 hours.
A styrofoam cooler would work nicely, and many people have used them successfully as tempeh incubators. Turn it on it's side so the open side (which will be the "door") faces you, just like the fridge door, and it would be oriented the same way for set up. You could just cut/push a hole in the back/side of it for the thermostat, and probably use a baking rack from a toaster oven or a baker's cooling rack or something else for a tray. Heat source and thermometer could the the light bulb and thermostat set up (like here), or a heating pad, hot water bottle, or warm room, space heater even (?) aimed into the box, and you can use a plain old thermometer to check the temp. Poke some holes in it to allow for air flow, or keep one side open, etc. Styrofoam is a great insulator, it's cheap, and it's easy to cut through/malleable, so perfect for the requirements of an incubator! There are other designs out there on the internet for styrofoam incubators, just google "styrofoam tempeh incubator." Some just use a hot water bottle on the bottom of the box as the heat source, with a thermometer inside, and leave the lid cracked, etc.
Happy Tempeh Making!
Happy Tempeh Making!