Data sheet
testo 425

Thermal anemometertesto 425 – Digital hot wire
anemometer with App connection

Simple, fast and precise flow and temperature measurement
plus volume flow calculation in the ventilation ductm/s

More flexibility for duct measurements with the cableconnected telescopic probe (maximum length 820 mm)

m3/h

Fast in-app (duct) configuration, graph history, second screen
and measurement data memory in the testo Smart App°C

Timed and point mean value calculation
Durability through compact design with robust housing

Bluetooth 5.0+ App
testo Smart Appfor free download

Optimally adjusted air conditioning and ventilation

to work overhead or in large diameter ducts. All relevant

systems are a decisive factor for modern buildings.

calculations, such as volume flow or time and point

Accordingly, it is important to use the appropriate

averages, are performed automatically by the particularly

measurement technology to ensure that the flow,robust and compact measuring instrument.

temperature and volume flow in the ventilation duct arecorrect.

Incidentally: Configuration of the measuring instrument,
display and storage of measured values as well as

The testo 425 thermal anemometer is your fast, easy

documentation are all particularly convenient with the testo

and precise companion. The cable-connected telescopic

Smart App. This also turns your smartphone into a second

probe can be extended up to 820 mm, making it easierdisplay.

www.testo.com

testo 425

Ordering data / technical data / accessories

Sensor types

testo 425, thermal hot wire anemometer with App
connection and fixed telescope (max. 820 mm),incl. carrying bag, calibration protocol and3 X AA batteries

Hot wire
Measuring range0.01 to 30 m/s

Accuracy ±1 digit±(0.03 m/s + 4% of m.v.) (0.01 to 20 m/s)±(0.5 m/s + 5% of m.v.) (20.01 to 30 m/s)

Resolution

0.01 m/s

NTC
Order no. 0563 0425

Measuring range-20 to +70 °C

Accuracy ±1 digit±0.5 °C (1 to 30 m/s)

Resolution

0.1 °C

1981 2244/oa/07.2023

testo 425

Operatingtemperature

Measuring instrument: -20 to +50 °C
Probe: -20 to +70 °C

Storage temperature-20 to +50 °C

Battery type3 x AA

Battery life

35 hDimensions

Measuring instrument: 135 x 60 x 28 mm
Probe: Length 180 mm, Ø 7.5 mm
Cable length 1.5 m

Weight268 g

Protection class

Measuring instrument: IP 40
Probe: IP20

Housing material

ABS + PC / TPE

Accessories

Order no.

• Simple and fast: Measurement menus fornumerous applications provide optimum support inconfiguring and carrying out the measurement

testo Bluetooth® printer, incl. 1 roll ofthermal paper, rech. battery and mains
unit0554 0621• Clear graphical presentation of readings, e.g. as atable, for quick interpretation of results

Spare thermal paper for printer (6 rolls),
measurement data documentation can beread for up to 10 years

0554 0568

ISO calibration certificate for flow, hotwire/vane anemometer, Pitot tube;
calibration points 1; 2; 5; 10 m/s

0520 0004

ISO calibration certificate for flow, hotwire/vane anemometer, Pitot tube;
calibration points 5; 10; 15; 20 m/s

0520 0034

ISO flow calibration certificate, hot wire,
vane anemometer, Pitot tube, calibration
points 0.3; 0.5; 0.8; 1.5 m/s

0520 0024

The testo Smart App• Create digital measurement reports including
photos as PDF/CSV files on site and send via
e-mailFree download

for Android and iOS

www.testo.com

Subject to change, including technical modifications.

General technical data