So I need a cabinet to raise bread and mature koji ferments...

So I designed one. I have not yet built it, because I have not yet bought the pans and tubs to go in it, so I don't know how big it needs to be. Since building something with one function is stupid, I have designed it to be able to ferment warm ferments, with or without humidity, and the holes top and bottom with flaps(I haven't drawn them) to regulate air flow and hardware cloth grates would convert this cabinet into a vegetable dehydrator. Oh, and if we park it outside, it can be used to smoke bacon and jerky.

What kind of temps are you hoping to maintain? How much deviation is tolerable? At 1,100 watts, I think it could heat too fast and overshoot the setpoint. Any idea how many watts it uses at very low setting? My seed dryer is only 60 watts, but easily maintains ~90° F. (Mind you: it's an old lab incubator with a muffin fan added on top. It's well insulated, and only has ~ a cubic foot of volume.)

Maybe you could mitigate (If it IS an issue.) by lowering to minimum wattage, and / or installing a mass between the heat and the rest of the space.

Where would you put the thermostat? Near the top would probably cycle on and off less often, but increase risk of overshooting the setpoint. Closer to the heat source would reduce the risk, but probably cycle often.

I wonder how putting the heat at the top with a fan would work? Looks like you were hoping for simple convection, with no fan, so maybe scratch that idea.

T Melville wrote:What kind of temps are you hoping to maintain? How much deviation is tolerable? At 1,100 watts, I think it could heat too fast and overshoot the setpoint. Any idea how many watts it uses at very low setting? My seed dryer is only 60 watts, but easily maintains ~90° F. (Mind you: it's an old lab incubator with a muffin fan added on top. It's well insulated, and only has ~ a cubic foot of volume.)

Maybe you could mitigate (If it IS an issue.) by lowering to minimum wattage, and / or installing a mass between the heat and the rest of the space.

Where would you put the thermostat? Near the top would probably cycle on and off less often, but increase risk of overshooting the setpoint. Closer to the heat source would reduce the risk, but probably cycle often.

I wonder how putting the heat at the top with a fan would work? Looks like you were hoping for simple convection, with no fan, so maybe scratch that idea.

Different temps for different applications. Supposedly the controller is accurate to within 5°F. But I also have an analog thermometer to check the temp so I can troubleshoot it. I just made a skp file with both an electric and charcoal model. I coild shoot it to your email if you wanna see it better.

Sorry, I get ahead of myself sometimes. I tried to put the troubleshooting ahead of the building and testing. The "problem" is only a potential problem. You don't have a problem to solve, at least not yet. I think your design looks pretty solid, pending a good match of volume to insulation to heating potential. Also note, a hotplate like yours is the heat source Alton Brown used to hot-smoke a salmon in a cardboard box. I think you have the right ideas, so long as you're careful with decisions about size and materials. Let us know how it turns out, I like ptojects like this one.

Sorry for the quality of this. Whoever uploaded it botched the resolution and didn't capture the whole screen.Only copy I could find.