The Testo 420 Flow Hood is a lightweight, precise, and user-friendly solution designed for regulating volume flows at supply and return vents. A key advantage is its flow straightener: it significantly improves measurement accuracy at turbulent outlets—eliminating the hassle and time wasted on tricky, low-accuracy readings in such scenarios. Handling is made especially easy by its low weight (less than 6.2 lbs) and ergonomic handles, reducing fatigue during extended on-site use.

The flow hood’s display is tiltable, allowing for more comfortable readout at different angles. Additionally, Bluetooth connectivity enables pairing with mobile devices, which can function as a second display or remote control. This feature simplifies use with an optional tripod (ideal for high ceilings, as users can operate the flow hood from the ground). Furthermore, the Testo mobile App lets users finalize and send measurement reports directly on-site, streamlining workflow and eliminating the need to complete reports later in the office.

Features

• Spacious 24" x 24" (610 x 610 mm) hood, compatible with most standard supply and return vents for versatile use
• Wide volume flow range (40 to 4000 m³/h), covering the needs of most commercial and residential HVAC volume flow regulation tasks
• Multi-parameter measurement capability:
  • Temperature: -4 to 158°F (-20 to 70°C) (measuring range)
  • Humidity: 0 to 100 %RH
  • Differential Pressure: -120 to 120 Pa
  • Absolute Pressure: 700 to 1100 hPa
• Narrow operating temperature range (23 to 140°F (-5 to 60°C)), optimized for typical indoor HVAC working environments
• 3.5" removable display, offering flexibility in readout placement (e.g., detached for hard-to-reach areas)
• Flow straightener, specifically designed to enhance measurement accuracy at turbulent outlets—solving a common pain point in flow measurement
• Lightweight design (less than 6.2 lbs) with ergonomic handles, reducing user fatigue during prolonged use or frequent repositioning
• Tiltable display, ensuring clear readout regardless of the user’s standing position or the hood’s installation angle
• Bluetooth connectivity to mobile devices, enabling second-display functionality, remote control, and seamless integration with the Testo App
• On-site report generation via the Testo App, allowing users to finalize, share, and store measurement reports immediately after testing—saving time on post-site paperwork