Description

Included in the Hot Wire Kit

Delivery Scope

testo 440 air velocity and IAQ measuring instrument, 3 x AA batteries, USB cable and calibration protocol
Hot wire probe (Ø 9 mm) with fixed cable (length 1.7 m) including temperature sensor, with telescope (can be extended to 0.85 m) and calibration protocol (0635 1032)
Basic case for testo 440 and 1 probe

Use the hot wire probe with the compatible testo multifunction measuring instrument (please order separately) to determine air velocity, volume flow and air temperature.

Hot wire probe – features

Use the fixed cable to connect the hot wire probe to the measuring instrument.

The probe is equipped with a telescope, which can be extended to a maximum length of 0.85 m. To ensure accurate measurement results, air density compensation is carried out via the integrated absolute pressure measurement.

The clearly structured measurement menu for volume flow makes the measuring instrument intuitive to operate. The volume flow is precisely calculated thanks to convenient input of the size and geometry of the duct cross-section. Timed and multi-point mean calculation, average volume flow, current reading and min./max. values are displayed in the measuring instrument.

Integrated sensor protection: when you are not using the hot wire probe, the rotatable protective cap protects the air velocity sensor from dirt and mechanical stress.

Intelligent calibration concept

You will get exceptionally accurate measurement results with the digital probe, because the measuring instrument makes measurement uncertainty a thing of the past. You only need to send the probe in for calibration – so the measuring instrument remains in continuous use.

Areas of application for the hot wire probe

Ventilation ducts: Use the hot wire probe to measure air velocity and air temperature in ventilation ducts with reliability. Benefit from fast calculation of the volume flow: in the “volume flow” measurement menu of the compatible measuring instrument (please order separately), configure the dimensions and geometry of the duct cross-section – the measuring instrument shows you the volume flow straight away.

Delivery Scope

Hot wire probe (Ø 9 mm) with fixed cable (length 1.7 m) including temperature sensor, with telescope (can be extended to 0.85 m) and calibration protocol.

Additional information

Weight	0.25 kg
Dimensions	15.4 × 6.5 × 3.2 cm
testo 440	The testo 440 air velocity and IAQ measuring instrument, combined with high-precision probes (sold separately), enables accurate measurement and data logging of air velocity, indoor air quality (IAQ), humidity, temperature, CO2, and CO levels. It supports up to three simultaneous probes—Bluetooth, wired, and a temperature probe with a type K thermocouple connector—offering automatic probe detection and intuitive measurement menus for effortless operation. Designed for HVAC professionals, it simplifies tasks such as volume flow measurement, turbulence assessment (EN ISO 7730 / ASHRAE 55), and long-term IAQ monitoring. The Bluetooth handle eliminates cable clutter and enables wireless measurements up to 20 meters, while the device's internal memory stores up to 7500 measurement protocols, exportable via USB. The intelligent calibration system ensures high accuracy by requiring only the probes to be sent for recalibration. With a wide range of probes, including options for cleanrooms, fume cupboards, and laminar flow measurements, the testo 440 is a versatile, professional-grade tool for HVAC technicians, facility managers, and air quality specialists.
Probe	The hot wire probe, designed for use with a compatible testo multifunction measuring instrument (sold separately), accurately measures air velocity, volume flow, and air temperature. It connects via a fixed cable and features an extendable telescope up to 0.85 m. Integrated absolute pressure measurement ensures precise air density compensation, while the structured volume flow menu simplifies operation. The probe allows for timed and multi-point mean calculations, displaying real-time, average, and min/max values. A rotatable protective cap safeguards the air velocity sensor when not in use. Thanks to its intelligent calibration concept, only the probe needs recalibration, keeping the measuring instrument in continuous use. Ideal for ventilation ducts, it enables fast and reliable volume flow calculations. The hot wire probe comes with a 1.7 m fixed cable, built-in temperature sensor, extendable telescope, and calibration protocol.

Specifications for the Hot Wire Probe

Temperature – NTC

Measuring range	-20 to +70 °C
Accuracy	±0.5 °C
Resolution	0.1 °C

Absolute Pressure

Measuring range	+700 to +1100 hPa
Accuracy	±3.0 hPa
Resolution	0.1 hPa

Velocity – Hot wire

Measuring range	0 to 30 m/s
Accuracy	±(0.5 m/s + 5 % of mv) (0 to 20 m/s) ±(0.03 m/s + 4 % of mv) (20.01 to 30 m/s)
Resolution	0.01 m/s

General technical data

Storage temperature	-20 to +70 °C
Weight	90 g
Dimensions	315 x 12 x 12 mm
Operating temperature	-20 to +70 °C
Cable length	1.7 m
Length telescope	850 mm
Probe head diameter	9 mm
Diameter telescope	12 mm
Product colour	Black; silver
Diameter probe shaft	12 mm

Specifications for the Testo 440

Temperature – NTC

Measuring range	-40 to +150 °C
Accuracy	±0.4 °C (-40 to -25.1 °C) ±0.4 °C (+75 to +99.9 °C) ±0.5 % of mv (Remaining Range) ±0.3 °C (-25 to +74.9 °C)
Resolution	0.1 °C

Temperature – TC Type K (NiCr-Ni)

Measuring range	-200 to +1370 °C
Accuracy	±(0.3 °C + 0.3 % of mv)
Resolution	0.1 °C

General technical data

Weight	250 g
Dimensions	154 x 65 x 32 mm
Operating temperature	-20 to +50 °C
Connectable probes	1 x digital probe with cable or 1 x Temperature NTC TUC, 1 x digital Bluetooth probe or testo Smart Probe, 1 x Temperature TC Type K
Product colour	black/orange
Battery type	3 AA mignon 1.5 V
Battery life	12 h (typically vane measurement)
Interface	Bluetooth®; USB
Storage temperature	-20 to +50 °C