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 duct
fpmm/scfm

m3/h°F°C

More flexibility for duct measurements with the cableconnected telescopic probe (maximum length 32 in.)Fast in-app (duct) configuration, graph history, second screen
and measurement data memory in the testo Smart App
Timed and point mean value calculation
Durability through compact design with robust housing

Bluetooth
5.0 + Apptesto Smart App
for free download

Optimally adjusted air conditioning and ventilationsuch as volume flow or time and point averages, aresystems are a decisive factor for modern buildings.

performed automatically by the and compact measuring

Accordingly, it is important to use the appropriate

instrument.

measurement technology to ensure that the flow, temperatureand volume flow in the ventilation duct are correct.

Configuration of the measuring instrument, display andstorage of measured values as well as documentation are

The testo 425 thermal anemometer is your fast, easy andavailable with the testo Smart App. This also turns yourprecise companion. The cable-connected telescopic probe

smartphone into a second display to give you more flexibility

can be extended up to 32 in., making it easier to workon the job.

overhead or in large diameter ducts. All relevant calculations,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. 32 in.), incl.
carrying bag, calibration protocol and3 X AA batteries
Order no. 0563 0425

Vane
Measuring range

0 to 5,905 fpm

Accuracy ±1 digit±(5.91 fpm + 4% of m.v.) (0 to 3,937 fpm)±(98 fpm + 5% of m.v.) (3937.1 to 5,905 fpm)

Resolution

0.01 fpm

NTC
Measuring range-4° to 158 °F

Accuracy ±1 digit±0.9 °F

Resolution

0.1 °F

1981 2244/msp/09.2022

testo 425

The testo Smart App

Operating temperature

Measuring instrument: -4° to 122 °F
Probe: -4° to 158 °F

Storage temperature-4° to 122 °F

Battery type3 x AA

Battery life

35 hDimensions

Measuring instrument: 5.3 x 2.4 x 1.1 in
Probe: Length 7.1in, Ø 0.30 in
Cable length 5 ft.

Weight0.60 lbs.

Protection class

Measuring instrument: IP 40
Probe: IP20

Housing material

ABS + PC / TPE

Accessories

Order no.

testo Bluetooth printer, incl. 1 roll of thermal paper,rech. battery and power supply

0554 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 be read forup to 10 years

0554 0568• Create digital measurement reports including photos
as PDF/CSV files on site and send via e-mail

NIST Temperature Certificate pick 3 standard points
between -20, +10, +25 and +40°C

400520 1901

NIST Temperature Certificate pick 3 custom points
between -20 and/or from +5 to +70°C

400520 1902

NIST Velocity Calibration: 3 Standard Points

400520 4401

NIST Velocity Calibration: 3 Custom Points

400520 4402

• Simple and fast: Measurement menus for numerous
applications provide optimum support in configuring
and carrying out the measurement

Free downloadfor Android and iOS®

www.testo.com

Subject to change, including technical modifications.

General technical data