The testo 400 is a highly advanced, universal IAQ instrument designed to support professionals in the fields of air conditioning, ventilation, and environmental monitoring. It allows users to measure, analyse, and document all IAQ and comfort parameters using a single, intuitive device. Whether you’re working on air flow measurements, temperature and humidity levels, or assessing air quality, the testo 400 offers the versatility and accuracy required to get the job done.

With high-quality measuring technology and smart measurement assistants, the testo 400 supports a wide range of applications, from standard-compliant HVAC grid measurements to long-term monitoring of indoor air quality. Its built-in sensors for differential pressure and absolute pressure enable location-independent, highly precise measurements.

You can also connect the testo 400 with a broad range of compatible Bluetooth® and cable probes, making it flexible for any measurement task. This includes flow velocity, CO2 and CO, radiant heat, illuminance, and turbulence. It even integrates with the testo 420 volume flow hood to manage volume flow measurement at large air inlets and outlets.

The instrument also supports long-term monitoring via an IAQ data logger for continuous air quality measurements. Furthermore, the testo 400 offers smart features such as measurement programs tailored to specific standards (like EN ISO 7730 and ASHRAE 55), and customer management tools to help you work efficiently on-site.