New HUMICAP® humidity sensor (HUMICAP180R or HUMICAP180V) New filter (always recommended when replacing the sensor) Duct models only: medium size crosshead screwdriver (Pozidriv) Power down the transmitter. Duct models only: loosen the tightening screw on the fastening flange and pull the probe out of the duct. Remove the filter to access the sensors. 1 Vaisala HUMICAP® sensor. Handle by the plastic frame. 2 Temperature sensor. Do not touch or attempt to remove. 3 Sensor socket. 4 Transmitter probe. Pull out the old HUMICAP® sensor and insert the new one. Perform a two-point humidity calibration on the serial line using the FCRH command. Insert the new filter. Duct models only: push the probe back into the duct, to the same depth where it was before. Tighten the tightening screw on the fastening flange. Power up the transmitter. Related conceptsTwo-point humidity calibration and adjustment using computer and HMK15 Humidity Calibrator