An apparatus for indirectly determining the dew point of compressed air at a particulate operating pressure including a capacitive sensor for measuring a relative humidity, a heating element for both heating and cooling a fraction of the compressed air, a controller for controlling the heating element based on a measured relative humidity, a temperature sensor for determining the temperature of the fraction. The controller is further configured to control the heating element such that the fraction is maintained at a predetermined constant relative humidity such that the dew point can be determined based on the temperature of the fraction.

An apparatus for indirectly determining the dew point of compressed air at a particulate operating pressure including a capacitive sensor for measuring a relative humidity, a heating element for both heating and cooling a fraction of the compressed air, a controller for controlling the heating element based on a measured relative humidity, a temperature sensor for determining the temperature of the fraction. The controller is further configured to control the heating element such that the fraction is maintained at a predetermined constant relative humidity such that the dew point can be determined based on the temperature of the fraction.