Testo 420 Replacement Hood 305 x 1220mm

The Testo 420 replacement hood (305 × 1220mm) is designed for accurate volume flow measurement at long, narrow linear slot diffusers and ventilation grilles. The integrated flow straightener physically calms turbulent airflow before it reaches the sensor matrix — eliminating the bouncing readings that make slot diffuser balancing so difficult and ensuring your commissioning report is accurate.

This hood attaches directly to your existing Testo 420 volume flow hood base and comes with a durable carry bag. Not sure which hood size you need? See our Testo 420 hood selection guide or browse the full flow hood range at HVAC Shop AU.

Key Features

• 305 × 1220mm nominal dimensions — ideal for linear slot diffusers
• Inner dimensions: 280 × 1195mm
• Integrated flow straightener for high-precision measurement at turbulent outlets
• Minimum outlet requirement: 335 × 335mm
• Attaches directly to Testo 420 volume flow hood base
• Includes durable carry bag

Suitable For

• Commercial office HVAC balancing and commissioning
• Cleanroom ventilation verification
• Modern architectural HVAC installations with slot diffusers
• NEBB certified professionals and commissioning agents

What’s Included

• Replacement hood 305 × 1220mm (product no. 0554 4201)
• Carry bag