The Testo 405i is a wireless hot wire anemometer designed for fast, accurate measurement of air velocity, temperature, and volume flow inside HVAC ducts. Its compact probe (<0.5 inch diameter) with a telescopic shaft that extends to 15 inches allows easy access to hard‑to‑reach locations, making it ideal for in‑duct traverses and leakage testing.

Operating via the Testo Smart Probes App on any iOS or Android device, the 405i eliminates the need for a dedicated display unit. The app provides a clear, customizable dashboard that can simultaneously show readings from up to six smart probes. Users can configure duct shapes and dimensions directly in the app to automatically calculate volume flow in real time. Measurement data can be visualized as instrument readings, tables, or graphs, and exported as PDF or Excel files for professional reporting.

Key measurement capabilities include air velocity from 0 to 6,000 fpm, volume flow up to 99,999 cfm, and temperature from -4 to 140°F. The instrument supports multiple units and is backed by a two‑year warranty, ensuring long‑term reliability for HVAC professionals.

Typical applications include:

• Duct air velocity profiling and flow balancing
• Air duct leakage testing according to standards
• HVAC system commissioning and troubleshooting
• VAV terminal unit verification

Features

• Wireless connectivity to Testo Smart Probes App (iOS/Android)
• High‑precision hot wire sensor with 0–6,000 fpm velocity range
• Volume flow calculation with configurable duct dimensions
• Temperature measurement from -4 to 140°F
• Ultra‑compact probe (<0.5 in) with 15 in telescopic extension
• Multi‑point averaging and timed traverses
• Export PDF/Excel reports and share via email
• Connect up to six probes simultaneously
• Rugged design, 2‑year warranty