I’ve now followed how the modified fridge works with just one temperature. So it is time to add the second temperature zone into it for creating a cheese cave and maturing the cheeses. This turned out to be really straight forward and easy.
The idea on creating a cheese cave
My plan was to put a Styrofoam box in the fridge and some small heater, that would maintain the box at 13C, while the outside is the crispy 4C. So the first thing was to find a suitable heater.
I had some extra 12V Halogen bulbs that I had changed into LEDs. So I wired a lamp and placed it into the box and started measuring the temperature. I wired the controller to the lamp at the same time to see how it would work. Heating the box at room temperature to 30C worked like a charm. So concept proven!
I was one step closer to creating a cheese cave.
The practice
So I attached the second controller to the mains of the first controller, and wired an extension cord as the load. I then placed a 12V power supply to the extension cord and installed both the temperature controller sensor wire and the 12V wire to the fridge through the hole I drilled earlier.
I placed the Styrofoam box into the fridge and placed the sensor and lamp inside the box. And that was it! Sure I taped the controllers on top of the fridge and hid some wires inside the old thermostat box.
Just to take advantage of the 12V lead inside the fridge, I also installed the old trustworthy computer case fan to increase the air circulation inside the fridge. I noted that the fridge’s own fan isn’t powerful enough to mitigate the sedimentation of clod air. The temperature probe is at the top of the fridge, and when it shows 4C, the bottom of the fridge is closer to 2C.
Conclusions
The setup works like a charm. The styrofoam box maintains a nice temperature between 11 and 13C, while the fridge is kept between 3,8 and 4,5C. The halogen bulb inside the white Styrofoam box creates an eerie feeling, when the lights are out. My kids thought the fridge was haunted, as the box started glowing and suddenly turned off
Even though I’m fairly certain that the setup will work, I’m a bit worried about energy consumption. It is fairly stupid to use energy to heat a space that is being refrigerated. My plan is to replace the halogen bulb with a thermoelectric cooling element (i.e. a peltier-element). That way, the heat inside the cheese cave will be drawn from the fridge itself. That way the energy used to heat the box is also used to cool the fridge. Whereas currently, I’m heating AND cooling the fridge at the same time.
So stay tuned!