Airflow is one of the most critical measurements for proper air conditioning performance. The correct measurement of AirFlow is also important in air leakage testing and weatherization work. The compact testo 425 is an easy to use thermal (hot-wire) anemometer attached to a telescoping shaft. Just enter the duct area measurements directly into the testo 425 and volume flow measurements (CFM) are clearly shown on the backlit display. Timed and multi-point mean flow calculations allow quick, easy and accurate airflow measurement. Min-Max values are one button simple, while the "Hold" function freezes the current readings in the display for easy data recording. Bright back light for dark areas
The primary advantages of hotwire anemometers are sensitivity, pin point accuracy, and ease of use. The telescoping probe allows for a full duct traverse with an automatic calculation of the CFM in the duct if the dimensions are input into the instrument before the measurement is taken. If done carefully the measurement error will be less than 3% and often as little as 1% total error.