Per Drieaz - The Dri-Eaz PHD 200 Dehumidifier features 2 operating modes: humidistat and continuous operation. Humidistat mode maximizes moisture removal efficiency by maintaining a preset humidity level in your workspace. Once you set your desired humidity level, the dehumidifier's compressor cycles on and off to maintain that level while the fan continues running for more accurate humidity measurement. Use continuous mode when you need to reduce the humidity in your space fast with no downtime. Your space's temperature and relative humidity is displayed on the control panel in real time for convenient tracking.