In dry climates, proper wine cellar humidity is essential.
Low wine cellar humidity causes dryness of the corks resulting in loss of liquid in the bottles. High wine cellar humidity causes mold and degradation of the labels and glue.
Wine Guardian cooling units control both cooling and dehumidification. That is, they cool the cellar air down below its dew point, which causes moisture to condense out and drip into a drain pan. The water is then removed by an external drain line or re-evaporated by a heated coil in the external section of the unit. This combination of cooling and dehumidifying generally keeps the cellar at the proper temperature and humidity during the cooling season.
A cooling unit alone cannot add moisture or humidify the cellar air. It needs a humidifier to do so. The best option is where the wine cellar humidifier is integrated into the cooling unit so it operates and distributes the moisture evenly in the re-circulating air. A freestanding humidifier also can be used but should be one controlled by a quality wall-mounted humidistat. Again, the wine cellar humidifier should have a capacity rated at the temperature of a wine cellar and not at room temperature nor at furnace discharge temperature, as many are.