DatasheetThe testo 425 Digital Hot Wire Anemometer delivers fast, precise air velocity, temperature, and volume flow measurements. With an extendable telescopic probe and App support for smart configuration and reporting, it’s a powerful tool for HVAC professionals.
At the heart of its performance is a cable-connected telescopic hot wire probe that extends up to 820 mm, allowing easy access to hard-to-reach or overhead ducts. The instrument is optimised for use in HVAC and ventilation systems, where precise readings and efficient data handling are essential.
With built-in automatic calculations, the device can generate time and multi-point averages and compute volume flow directly, saving time and eliminating manual errors. For even greater efficiency, the testo Smart App allows users to configure measurements, view real-time data on a smartphone (as a second screen), and manage results with graph visualisation, memory storage, and fast report generation.
Rugged, lightweight, and user-friendly, the testo 425 is the ideal choice for professionals looking for a smart, dependable solution to ventilation flow diagnostics.
Delivery Scope
- testo 425 – Thermal hot wire anemometer with App connection and fixed telescope (max. 820 mm)
- Transport bag
- Calibration protocol
- 3 x AA batteries
Technical data
Temperature – NTC
| Measuring range |
-20 to +70 °C
|
|---|---|
| Accuracy |
±0.5 °C
|
| Resolution |
0.1 °C
|
Velocity -Thermal anemometer
| Measuring range |
0.01 to 30 m/s
|
|---|---|
| Accuracy |
±(0.5 m/s + 5.0 % of mv) (20.01 to +30 m/s)
±(0.03 m/s + 4.0 % of mv) (0.01 to +20 m/s)
|
| Resolution |
0.01 m/s
|
General technical data
| Weight |
268 g
|
|---|---|
| Dimensions |
135 x 60 x 28 mm
|
| Operating temperature |
Probe: -20 to +70 °C
-20 to +50 °C
|
| Product-/housing material |
ABS + PC / TPE
|
| Cable length |
1.5 m
|
| Diameter probe shaft |
7.5 mm
|
| Protection class |
IP20
|
| Length probe |
180 mm
|
| Battery life |
35 h
|
| Battery type |
3x AA
|
| Storage temperature |
-20 to +50 °C
|
