testo 440

Three Probes at the Same Time

This is the capability that separates the testo 440 from a single parameter meter, and it changes how a job is done.

The instrument takes three probes at once: one Bluetooth probe (a digital Bluetooth probe or a testo Smart Probe), one wired digital or NTC probe, and one Type K thermocouple. Three readings are displayed side by side.

That matters because ventilation measurements are related. Air velocity on its own tells you a fan is moving air. Air velocity alongside temperature and CO2 tells you whether it’s moving the right air to the right place. Measuring them one at a time means conditions have shifted between readings, so the numbers describe slightly different moments.

Measurement Menus for the Job

Clearly structured measurement menus for the most common HVAC tasks are stored on the instrument. They cover volume flow in ducts and at outlets, K-factor, degree of turbulence, cooling and heating load, mould indication and a logging mode for longer term measurement.

That means you get through each measuring task more quickly and reliably, without setting up calculations by hand.

Probe Identification

The instrument identifies each probe as it’s connected. Compatible Bluetooth probes connect automatically.

That removes a specific error: a reading taken while the instrument is still set up for the previous probe. That’s worse than an obvious fault, because the reading looks plausible and nobody questions it.

Draught Isn’t Subjective

The most useful measurement on this instrument is the one many people don’t know exists.

Draught complaints are the classic facilities argument. Someone says an area is draughty, someone else sits in the same spot and says it’s fine, and there’s no way to settle it, because it feels like a matter of opinion.

It isn’t. Draught rate can be calculated, from air velocity, the turbulence of that air and the air temperature. The testo 440’s draught rate menu, with the turbulence probe, calculates it in accordance with DIN EN 13779 or DIN EN ISO 7730, and shows the result as green (0 to 20%), yellow (21 to 30%) or red (31 to 100%).

So a complaint becomes a figure, which can be compared against a requirement and used to justify a change. For open plan offices, meeting rooms, laboratories and anywhere thermal comfort is contested, that turns an argument into an assessment.

The dP Version

Two versions are available: the standard testo 440, and the testo 440 dP with an integrated differential pressure sensor.

The differential pressure sensor measures from -150 to +150 hPa. It makes measurements at filters possible, as well as Pitot tube and K-factor measurements. In a cleanroom, an isolation room, a switchroom or a paint booth, the pressure relationship between spaces is the control, not a side effect.

If the work involves pressure at all, specify the dP version. The sensor is integrated, so it can’t be added later.

Probes and Kits

Probes are ordered separately or as a kit set up for an application. The range covers air velocity by hot wire, vane and thermal probe, CO2 with humidity and temperature, CO, humidity and temperature, high precision humidity, turbulence and lux, plus Testo’s temperature probes.

The high precision humidity and temperature probe is worth noting on its own. At ±(0.6% RH + 0.7% of reading) from 0 to 90% RH, it suits work where humidity needs to be measured very accurately.

A universal handle takes interchangeable probe heads, so the measurement range can grow without buying another instrument. A telescope extends the air velocity probes, to reach ceiling outlets from the floor.

Data and Reporting

The testo 440 stores up to 7,500 measurement protocols. Reports can be exported as Excel files over USB, or printed on site with Testo’s Bluetooth printer.

Where It Sits Against the testo 400

Both are multifunction air velocity and IAQ instruments, and the overlap is real.

The testo 440 covers three probes at once and the measurement menus needed for most HVAC commissioning, fault finding and IAQ work. For a technician doing that work regularly, it’s the right instrument.

The testo 400 sits above it, and is the choice where more channels, more extensive reporting or larger measurement programmes are needed.

Our Technical Consultants will work through which parameters your assessment has to show before recommending either, since the probe selection matters more than the instrument choice.

Where It’s Used

HVAC commissioning and balancing. Ventilation checks and defect investigation. Indoor air quality assessment in offices, schools and healthcare. Thermal comfort and draught complaint investigation. Laboratory checks. Carpark ventilation checks. Commercial kitchen and laundry ventilation. Data centre airflow. Isolation and negative pressure rooms (dP version). Building tuning and energy optimisation.