The warmed probe is suitable for climates with high humidity. It is ideal for tropical, coastal, and marine installations. It helps the sensor stay dry reducing the chemical contamination and minimizing drift.
In changing temperatures with high humidity, the probe temperature can lag behind the temperature of the surrounding air causing a risk of condensation on the sensor. A wet probe cannot observe the actual humidity in the ambient air. If the condensed water is contaminated, the life span of the probe may shorten and the calibration change.
The temperature of a warmed probe is always higher than that of the environment. This prevents condensation on the probe. With the additional temperature probe it is possible to calculate the true RH based on the non-heated (ambient) temperature information. If you have selected warming but the additional temperature probe is not present, HMP155 only produces dew point and mixing ratio output.
The warmed probe function works with 12 VDC but the heating starts slower. For optimal heating with the warmed probe function, use 16 VDC.