Humidity sensors

Robust sensors for energy efficiency and long life cycle

Humidity sensors visual

When it comes to energy-optimised control concepts, Symaro humidity sensors guarantee fault-free operation for years, even in critical applications.

Thanks to the capacitive measurement element, they feature excellent long-term stability with high accuracy, freedom from maintenance and high precision. Microprocessor technology and a sophisticated algorithm for temperature compensation ensure very high accuracy not only in the comfort range, but over the entire measurement range. Additionally, the sensors are impervious to dust and most chemicals.

Highlights at a glance

  • Energy efficiency with long life cycle – thanks to outstanding longterm stability with a high level of accuracy, freedom from maintenance, and precision

  • Reliable operation even in critical applications

  • High degree of reliability – thanks to innovative, FDA- and GMP-certified precision measuring sensors

  • Best quality, accuracy and reproducibility thanks to high-precision calibration laboratory


QFA20.. – standard room sensors

Standard room sensor

In ventilating and air conditioning plants to acquire relative humidity and temperature in rooms. The QFA20.. is used as a control and measuring sensor for building automation and control systems or indicating units.

Range of use:

  • Version: r.h.; r.h/T

  • Humidity: 0…95% 

  • Temperature: -15...50 °C 

  • Supply: AC 24 V / DC 13.5…35 V  

  • Output: AC 24 V / DC 13.5…35 V

  • Protection class: IP30 

Link to more information:


QFA31.. – high quality room sensors

High quality room sensor

The QFA31.. is for use in ventilation and air conditioning plants where high accuracy and short response times for measuring relative humidity are required. The measuring range covers the entire humidity range of 0…100%. The sensor is also available with LCD display.

Range of use:

  • Version: r.h.; r.h./T

  • Humidity: 0…100%

  • Temperature: -40...70 °C

  • Supply: AC 24 V / DC 13.5…35 V

  • Output: DC 0...10 V / DC 4...20 mA

  • Protection class: IP65

Link to more information:


QFA41.. – certified room sensor

Certified room sensor

The QFA41.. sensor is used in ventilation and air conditioning plants requiring very high accuracy and reliability for measuring relative humidity and temperature where calibration certificates are needed.

Range of use:

  • Version: r.h; r.h/T 

  • Humidity: 0…100%

  • Temperature: -40...70 °C

  • Supply: AC 24 V / DC 13.5…35 V

  • Output: DC 0...10 V / DC 4...20 mA

  • Protection class: IP65

Link to more information:


QFM21.. – standard duct sensors

Standard duct sensor

The QFM21.. duct sensors are for use in air ducts of ventilation and air conditioning plant for acquiring the relative humidity and the temperature. The sensors are used as control sensors in the supply or extract air; as reference sensors, e.g. for shifting the dew point; as limit sensors, e.g. in connection with steam humidifiers or for measured value indication.

Range of use:

  • Versionr: r.h; r.h/T

  • Humidity: 0…95 %

  • Temperature: -15...50 °C

  • Supply: AC 24 V / DC 13.5…35 V

  • Output: DC 0...10 V / DC 4...20 mA

  • Protection class: IP54

Link to more information:


QFM31.. – high quality duct sensors

High quality duct sensor

The QFM31.. is for use in ventilation and air conditioning plants where high accuracy and short response times for measuring relative humidity are required. The QFM31.. is used as a control sensors in the supply or extract air, as limit or measuring sensor.

Range of use:

  • Version: r.h.; r.h./T

  • Humidity: 0…100%

  • Temperature: -40...70 °C

  • Supply: AC 24 V / DC 13.5…35 V

  • Output: DC 0...10 V / DC 4...20 mA

  • Protection class: IP65

Link to more information:


QFM41.. – certified duct sensor

Certified duct sensor

The QFM41.. sensors are used in ventilation and air conditioning plants requiring: very high accuracy and reliability for measuring relative humidity and temperature where calibration certificates are needed.

Range of use:

  • Version: r.h.; r.h./T

  • Humidity: 0…100%

  • Temperature: -40...70 °C

  • Supply: AC 24 V / DC 13.5…35 V  

  • Output: DC 0...10 V / DC 4...20 mA 

  • Protection class: IP65

Link to more information:


QFA10.. – room hygrostats

Room hygrostats

The room hygrostats with an additional setpoint adjuster are used for controlling and monitoring relative humidity in ventilation or air conditioning plant.

Range of use:

  • Version: r.h. 

  • Humidity: 30…95% 

  • Output: Relay

  • Protection class: IP20

Link to more information:


QFM81.. – duct hygrostats

Duct hygrostats

The duct hygrostats are designed for controlling and monitoring the relative humidity in ventilating and air conditioning plants. In air conditioning plants with humidification, the duct hygrostat can also be used as a maximum limiter in the supply air duct.

Range of use:

  • Version: r.h.

  • Humidity: 15…95%

  • Output: Relay

  • Protection class: IP30 / 55

Link to more information:


AQF31.. – outside sensor

Outside sensor

The QFA31.. is for use in ventilation and air conditioning plants where high accuracy and short response times for measuring relative humidity are required. The measuring range covers the entire humidity range of 0…100%. With the accessory AQF3100 the QFA31.. is for outdoor use.

Range of use:

  • Version: r.h.; r.h./T

  • Humidity: 0…100%

  • Temperature: -40...70 °C

  • Supply: AC 24 V / DC 13.5…35 V

  • Output: DC 0...10 V / DC 4...20 mA

  • Protection class: IP65

Link to more information:


QXA2000 – dew point sensors

Dew point sensor

The sensor is used for monitoring condensation in buildings with chilled ceilings or in ventilation, air conditioning or heating plant.The condensation monitor is used to prevent condensation on chilled ceilings or critical spots of HVAC plant or buildings (in air ducts, nearfans, etc.).

Range of use:

  • Humidity: 5…95%

  • Supply: AC 24 V

  • Output: Relay

  • Protection class: IP40

Link to more information: