The Testo 405i thermal anemometer is a handy tool for HVAC techs, apprentices, and anyone working on ventilation systems, letting you quickly measure air velocity, temperature, and volume flow. Its extendable probe makes getting into ducts a breeze, and all your readings go straight to the Testo Smart App on your phone.

Working in tight ceiling spaces or on dusty rooftop units, trying to read a small display is a pain; this unit lets you keep your head clear and see the data on your smartphone.

Best For

• Measuring air velocity, temperature, and volume flow in ventilation ducts.
• Spot-checking indoor air velocity to locate draughts (e.g., non-airtight windows).
• HVAC technicians, installers, and service teams doing commissioning or troubleshooting.

Compatibility

This anemometer requires an iOS device running version 13.0 or newer, or an Android device running version 8.0 or newer. Your mobile device must also support Bluetooth 4.2 to connect with the Testo Smart App. The 405i can also be used in conjunction with other Testo Smart Probes, like the Testo 605i thermohygrometer, to calculate cooling capacities and heating outputs.

If you're running a different model, check fittings and specs before ordering.

Features

• Smartphone Operation: Connects wirelessly via Bluetooth to the Testo Smart App for easy viewing, analysis, and documentation of readings.
• Telescopic Probe: Extendable up to 400 mm (15.7 inches) for reaching into ventilation ducts and grilles, making access simpler.
• Calculates Volume Flow: Input duct cross-section geometry directly in the app for automatic volume flow calculations.
• Data Logging & Reporting: The app records measurement data trends, performs timed and multi-point mean calculations, and exports logs as PDF or Excel files.
• Multi-Parameter Measurement: Accurately measures air velocity, air temperature, and automatically calculates volume flow.

Technical Specifications

What's in the Box

• Testo 405i thermal anemometer
• Extendible telescope (400 mm)
• 3 x AAA micro batteries
• Calibration protocol

Using It on the Job

1. Install the Testo Smart App on your iOS (13.0+) or Android (8.0+) device and ensure Bluetooth 4.2 is enabled.
2. Insert the supplied AAA batteries into the 405i and power it on.
3. Connect the 405i to the Smart App via Bluetooth.
4. Extend the telescopic probe to the required length (up to 400 mm) and insert it into the ventilation duct or air grille.
5. Select the desired measurement (velocity, temperature, or volume flow) in the app. If measuring volume flow, input the duct cross-section details.
6. View real-time readings, trends, and perform calculations directly within the app, then save or export your data for reporting.

Limitations & Safety Notes

• Only use the device within its specified operating temperature range of -20 to +50 °C.
• The Smart App functionality requires a compatible smartphone or tablet with specific OS and Bluetooth versions.
• Avoid exposing the hot wire sensor to physical damage or harsh chemicals, which can affect measurement accuracy.
• Ensure batteries are correctly installed and replaced when low to prevent unexpected power loss during measurements.
• Follow Australian standards and Safe Work guidance when accessing ventilation systems, especially in elevated or confined spaces.

When taking multiple volume flow readings in a duct, take a grid pattern to get a better average. The app makes the mean calculation easy, saving you time with a pen and paper.

Pair With

Pair with a Testo 605i thermohygrometer to calculate cooling and heating outputs, or combine it with a Testo Smart Case for secure storage of your Smart Probes.