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Press and hold the ADJUST and MIN/MAX buttons at the same time for 5 seconds again, and the

indoor humidity value will begin flashing. Press the CHANNEL/+ button to increase the humidity

and the MIN/MAX/- button to decrease the humidity reading in 1% increments. To rapidly increase

(or decrease) the humidity reading, press and hold the CHANNEL/+ or MIN/MAX/- button.

To return the humidity to the actual or uncalibrated measurement, press the ADJUST button.

Once the displayed temperature or humidity equals the calibrated source, press and hold the ADJUST

button for three seconds, or wait 15 seconds for timeout, and the indoor temperature or humidity value

will stop flashing.

4.8.2 Outdoor Temperature and Humidity Calibration

Prior to entering the calibration mode, press the CHANNEL/+ button to select the outdoor

temperature and humidity you wish to adjust.

Press and hold the ADJUST and CHANNEL/+ buttons at the same time for 5 seconds and the

outdoor temperature value will begin flashing. Press the CHANNEL/+ button to increase the

temperature and the MIN/MAX/- button to decrease the temperature reading in 0.1° increments. To

rapidly increase (or decrease) the temperature reading, press and hold the CHANNEL/+ or

MIN/MAX/- button.

To return the temperature to the actual or uncalibrated measurement, press the ADJUST button.

Press and hold the ADJUST and CHANNEL/+ buttons at the same time for 5 seconds again, and the

outdoor humidity value will begin flashing. Press the CHANNEL/+ button to increase the humidity

and the MIN/MAX/- button to decrease the humidity reading in 1% increments. To rapidly increase

(or decrease) the humidity reading, press and hold the CHANNEL/+ or MIN/MAX/- button.

To return the humidity to the actual or uncalibrated measurement, press the ADJUST button.

Once the displayed temperature or humidity equals the calibrated source, press and hold the ADJUST

button for three seconds, or wait 15 seconds for timeout, and the outdoor temperature or humidity

value will stop flashing.

Discussion: Humidity is a difficult parameter to measure electronically and drifts over time due to

contamination. In addition, location has an adverse affect on humidity readings (installation over dirt

vs. lawn for example).

Official stations recalibrate or replace humidity sensors on a yearly basis. Due to manufacturing

tolerances, the humidity is accurate to ± 5%. To improve this accuracy, the indoor and outdoor

humidity can be calibrated using an accurate source, such as a sling psychrometer:

http://www.ambientweather.com/mafaredspslp.html

or one step humidpak calibration kits (reference Section 8). You can also use common table salt,

water and a plastic bag:

http://ambientweather.wikispaces.com/ws23

Discussion: Temperature errors can occur when a sensor is placed too close to a heat source (such

as a building structure, the ground or trees).

Ambient Weather WS-23 User Manual

Questions and Answers: