testo 405i Wireless Mini Hot-Wire Anemometer

Overview

The testo 405i Wireless Mini Hot-Wire Anemometer is an engineered solution for precise, portable air velocity, temperature, and volumetric flow measurement in HVAC commissioning, building diagnostics, and indoor environmental quality (IEQ) assessment. Based on constant-temperature anemometry (CTA), the device employs a thermally sensitive platinum wire probe maintained at a fixed temperature above ambient; convective cooling by airflow induces measurable resistance changes proportional to local air velocity. This principle enables high-sensitivity response across low-to-moderate flow regimes — critical for duct traverses, supply/return register verification, and leakage detection around windows and doors. Its compact form factor, telescoping 400 mm probe sleeve, and Bluetooth 4.0 wireless transmission eliminate cable constraints and enable real-time remote monitoring via mobile devices — supporting both spot checks and structured multi-point surveys without compromising metrological integrity.

Key Features

• Hot-wire sensor with 0.01 m/s resolution and traceable accuracy per ISO 17025-accredited calibration protocol included
• Integrated NTC temperature sensor (−20 to +60 °C) with ±0.5 °C accuracy, enabling simultaneous air velocity and temperature acquisition
• Telescoping probe sleeve extending to 400 mm for non-intrusive duct access and cross-sectional profiling
• Bluetooth 4.0 wireless communication ensures stable, low-latency data streaming to iOS (v11.0+) and Android (v6.0+) devices
• Lightweight (119.6 g), ergonomic housing constructed from high-strength polymer for field durability and one-handed operation
• 15-hour battery life on three rechargeable AAA cells; no proprietary charger required
• IP54-rated enclosure (dust-protected, splash-resistant) suitable for industrial and construction-site environments

Sample Compatibility & Compliance

The testo 405i is designed for clean, dry, non-corrosive air streams typical of HVAC systems, laboratories, and occupied buildings. It is not intended for use in saturated, particulate-laden, or chemically aggressive airstreams (e.g., exhaust stacks, fume hoods with solvent vapors). The instrument complies with EN 61326-1 (EMC for laboratory equipment) and meets CE marking requirements under the EU Electromagnetic Compatibility Directive. Calibration documentation adheres to ISO/IEC 17025 principles, supporting traceability to national standards (e.g., PTB, NIST). While not certified for hazardous locations (ATEX/IECEx), its operational range (−20 to +50 °C ambient, 0–100 %RH) aligns with ASHRAE Standard 111 and ISO 16813 guidelines for indoor air measurement instrumentation.

Software & Data Management

The testo Smart APP serves as the primary interface for configuration, visualization, and reporting. Users input duct geometry (rectangular or circular cross-section dimensions), and the app automatically computes volumetric flow rate (m³/h or CFM) using standardized traverse point algorithms aligned with ISO 12599 and ASHRAE Fundamentals Chapter 42. Real-time trend graphs, time-stamped multi-point averaging, and scheduled logging are supported. Data exports include PDF reports (with embedded calibration certificate ID) and Excel-compatible CSV files — both retaining full metadata (timestamp, GPS coordinates if enabled, operator ID, ambient conditions). Audit trails comply with GLP-aligned practices; though not FDA 21 CFR Part 11 validated out-of-the-box, the app supports user-defined password protection and export logs suitable for internal QA review.

Applications

• HVAC system balancing and commissioning: duct static pressure-independent velocity profiling
• Building envelope leakage assessment: localized air infiltration detection at window frames, door perimeters, and penetrations
• Indoor air quality (IAQ) surveys: correlation of air movement patterns with thermal comfort (PMV/PPD) modeling
• Energy audit support: combined use with testo 605i hygrometer enables sensible cooling/heating capacity estimation per ISO 5167-derived approximations
• Educational labs: hands-on instruction in fluid dynamics fundamentals, sensor physics, and wireless telemetry integration
• Maintenance diagnostics: identification of airflow obstructions, damper misalignment, or filter loading effects via comparative traverse maps

FAQ

Is the testo 405i suitable for outdoor wind speed measurement?
No — it is optimized for indoor and ducted airflow applications up to 30 m/s; unshielded outdoor use may compromise thermal stability and accuracy due to solar loading and turbulence.
Can multiple testo 405i units be operated simultaneously via one smartphone?
Yes — the testo Smart APP supports concurrent pairing with up to three compatible instruments, enabling synchronized multi-location monitoring.
Does the device require annual recalibration?
While not mandatory, testo recommends annual verification against a reference standard in accordance with ISO/IEC 17025 best practices, especially after mechanical shock or exposure beyond specified environmental limits.
What duct geometries does the software support for volumetric flow calculation?
Rectangular (user-defined width × height) and circular (diameter input) cross-sections; automatic grid generation follows log-Tchebycheff or equal-area methods per ISO 12599 Annex B.
Is the calibration certificate included with the device valid for ISO 9001 audits?
Yes — the factory-issued certificate references accredited calibration procedures and uncertainty budgets, fulfilling clause 7.1.5.2 (Monitoring and measuring resources) requirements when retained as part of quality records.