Humidity and Temperature Sensor Operating Guide
Combined humidity and temperature sensors measure relative humidity and ambient temperature for HVAC control, environmental monitoring, and process applications. Proper operation ensures accurate climate data.
I. Operating Principles
Relative humidity sensors typically use capacitive sensing elements where the dielectric constant of a hygroscopic polymer changes with moisture absorption. Temperature is measured using RTD or thermistor elements. The combination provides comprehensive environmental data from a single device.
II. Installation
- Mount the sensor away from direct sunlight, heat sources, and air vents that create localized conditions different from the representative environment
- Install at the appropriate height for the application, typically at breathing zone height for occupied spaces
- Use a radiation shield for outdoor installations to minimize solar heating effects on temperature readings
- Ensure adequate airflow around the sensor. Stagnant air can cause slow response and inaccurate readings.
III. Configuration
- Set the output signal type and range (analog or digital communication)
- Apply any required calibration offsets if sensor accuracy verification shows systematic errors
- Configure data logging intervals and alarm thresholds if the sensor supports these functions
IV. Calibration and Maintenance
- Verify humidity readings quarterly using a calibrated reference humidity generator or saturated salt solutions that produce known relative humidity values
- Verify temperature readings against a certified reference thermometer
- Clean sensor housings to prevent dust accumulation that can affect readings
- Replace sensing elements when accuracy drifts beyond acceptable limits, typically every one to two years
