Case #1: Enclosure humidity is too low
This is the most typical case when aging cheese due to the high %RH requirements and cool temperatures. If the external air temperature is several degrees above target temperature the compressor will cycle, de-humidifying the air each time. In very warm environments, or even at room temperatures this constant de-humidification will make it more difficult to add enough water vapor to replace what has condensed.
A popular method of adding humidity is to put a pan of water or damp towel inside the fridge. This will raise humidity but you will still be at the mercy of external and internal influences that make control difficult.
Below is a comparison of (1a) no control, (2a) wet towel and (3a) the Humidity Control System (set in humidification mode).
(Click on charts to enlarge)
1a: No control method
With the external temperature higher than the enclosure the compressor cycles every couple of hours. During each cycle the %RH drops more, and since there is no means to replace the humidity it will continue to drop even more. In a cheese cave the exposed cheese surfaces will "buffer" this drop depending on how much cheese is in the cave.
1b: Wet towel on shelf
A wet towel (or large water pan) will replenish the humidity that is condensed on the coils when the compressor cycles more when external temperatures are warm. Maintaining target humidity, though, may still be difficult especially when external temperatures can vary.
1c: Humidity Control System (humidify mode)
Note: Tests are scheduled for third week of January 2014 and will be posted as soon as we get them.