When brewing a lager in an apartment, you will most probably use a small refrigerator for the lagering process. If the refrigerator does not allow you to choose the exact temperature, but instead you set it using a number of power levels (1,2,3 and so on), how do you achieve the small rising of the temperature for the diacetyl rest?
It should be fairly easy to determine the actual temperatures your fridge stays at.
- Fill a bucket with water & put a thermometer in it. It doesn't have to be five gallons, two or three will do. The more water, the longer you must wait during step 3.
- Turn the fridge to the warmest setting and put the bucket in it.
- Allow the temperature to stabilize – probably a few hours.
- Check the temperature; record it along with the fridge's setting. For more accurate results, do this every five minutes until you discover the temperature range of the current setting.
- Turn the dial a half notch cooler and return to step three.
Depending on the model your refrigerator may keep temperatures in a 2-5º band.
You can be more clever by affixing a larger wheel with an arrow to the dial. This will give you finer control over the thermostat. Write the temperatures along the outside of the dial.