What is the difference between in-bottle liquid temperature control and wall mounted air temperature control?
When the cooling unit is controlled (turned on and off) by a sensor located in the liquid of a bottle sitting on a shelf, the wine itself will be subjected to the full temperature swing of the instrument. In other words, if the sensor and controller are rated at +/- 2°F, the wine temperature will change by 4°F with each on/off cycle. This will stress the wine and cause pre-mature aging. However, by sensing the cellar air temperature, even a +/-2°F thermostat will cause only a fraction of a degree change in the wine temperature. This is because of the thermal mass inertia of the liquid essentially insulated inside the glass bottle. The air temperature changes much faster than the liquid temperature as it is lighter and more sensitive to load variations. A good thermostat with a range of +/- 1°F will keep the wine at basically a constant temperature.
