- Temperature and flow measurement as well as volumetric flow calculation
- Permanently attached extendible telescopic probe – maximum length 820 mm, diameter 7.5 mm
- With single and multi-point averaging
- Hold function, display of min/max value, Auto-off function
In order to establish whether an air conditioning or ventilation system is functioning properly, among other things you need to check the flow speed or the volumetric flow in the ventilation duct. If the air flow velocity is too low, the room loads are not correctly discharged and optimum room air quality can no longer be guaranteed.
testo 425 thermal anemometer for quick, easy flow measurement
The testo 425 thermal anemometer enables quick spot measurements in ventilation ducts. It records the flow speed, calculates the volumetric flow and also measures the temperature. With a measuring range of 0 to +20 m/s, the anemometer is particularly well suited to low air flow velocity.
The thermal anemometer features a telescopic flow probe. The telescope can be extended to a length of up to 820 mm and has a probe head diameter of 7.5 mm.
As well as flow speed, would you also like to detect the volumetric flow on your air conditioning or ventilation system? This is no problem for the testo 425 thermal anemometer. When you input the duct surface area, it automatically calculates the volumetric flow during the flow measurement. Single and multi-point averaging provides an indicator of the average volumetric flow, flow speed and temperature reading.
You can read off the current readings and the min/max and calculated mean value at any time on the illuminated display. Using the Hold button, you can freeze the current reading in order to compare it with another value, for example. If you should ever forget to switch off the anemometer, the Auto-off function will take care of this for you. This conserves your batteries and ensures that your thermal anemometer is ready for use in the next measurement.
Equip yourself with accessories for the anemometer
To make sure that you are well-prepared for any circumstances, we recommend that when purchasing the anemometer, you also order our practical accessories: as an added option we offer a handy pocket, a transport case and also the TopSafe protective cover (to protect the anemometer from water, dirt and impacts).
testo 425 thermal anemometer with permanently attached flow probe including temperature measurement and telescope (max. 820 mm), calibration protocol and battery.
|Temperature - NTC|
|Measuring range||-20 to +70 °C|
±0.5 °C (0 to +60 °C)
±0.7 °C (Remaining Range)
|Velocity - Thermal anemometer|
|Measuring range||0 to +20 m/s|
|Accuracy||±(0.03 m/s + 5 % of mv)|
|General technical data|
|Dimensions||182 x 64 x 40 mm|
|Operating temperature||-20 to +50 °C|
|Battery type||9V block battery, 6F22|
|Battery life||20 h|
|Storage temperature||-40 to +85 °C|
Product brochure testo 425 (PDF, 292.3 kB)
Instruction manual testo 425 (PDF, 737 KB)