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.webp "Carbon dioxide detector wall mounting")
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EU declaration conformity
CO2 sensor | wall mounting | LED indicators | 24 V AC - V DC
Product description
Sensor for detecting temperature, relative humidity, CO2, and ambient light level in HVAC systems. The supply voltage is 24 V AC or 24 V DC. The green, yellow, and red LED indicators indicate the CO2 level.
The measured values are transmitted via Modbus RTU communication and three analogue outputs. The output type is set to 0-10 Volt by default but there are various output types available. Using ambient light detection, the ventilation system can be controlled based on room occupancy. All parameter settings can be adjusted using Modbus RTU communication. The light levels of the LEDs used for status indication can be adjusted.
This carbon dioxide sensor is commonly used to monitor carbon dioxide levels in schools, offices, and restaurants, among other places.
Additional specifications and description
Is there sufficient fresh air supply?
People produce CO2 or carbon dioxide while breathing. That makes CO2 concentration a good indicator for the occupancy and activity level in a space. The higher the occupancy or activity level, the more fresh air supply is required to maintain good indoor air quality. That is why in many applications, CO2 sensors are used as an indicator for the ventilation requirements. Next to CO2, this sensor also measures temperature, relative humidity and ambient light level. The measured temperature, relative humidity and CO2 level are available via the three analogue outputs and via Modbus RTU communication. The dew point and ambient light level are available via Modbus RTU communication.
Three analogue outputs to transmit the measured values
This sensor has three analogue 0-10 Volt outputs. Each of them transmits one of the measured values. E.g. by default, output 1 will transmit 0 Volt at 0 °C and 10 Volt at 50 °C. Each output value varies proportionally in function of the measured temperature, humidity or CO2 concentration. The measured temperature is available via output 1, relative humidity via output 2 and CO2 concentration via output 3. By default the output type is 0-10 Volt. Other output types can be selected via de Modbus holding registers.
Visual indication of the measured value 
This HVAC transmitter offers a clear, visual indication of the CO2 level via the green, yellow and red LED. The green LED indicates that the CO2 level is within range - there is sufficient fresh air supply. When the CO2 level enters the alert range, the yellow LED lights up. Red means: CO2 out of range or insufficient fresh air supply. The ranges can be adjusted via the Modbus holding registers. The LED indicators can visualize the status of one of the three measured values, by default CO2.
3-wire connection
The cage clamp terminal blocks reduce wiring and installation time. They eliminate the need for routine maintenance and guarantee a reliable contact for solid or stranded wires. This sensor can be supplied with 24 V DC or with 24 V AC. It is intended for 3-wire connection. The ground of the output (GND) is internally connected to the ground of the supply voltage (V-). Make sure not to connect this common ground to other devices that are powered by a DC voltage.
Photo-acoustic NDIR sensor element - ABC logic
Photo-acoustic sensors are highly sensitive and specific, making them useful for the detection of various gases such as pollutants, trace gases and volatile organic compounds. The use of specific infrared wavelengths corresponding to the absorption lines of CO2 ensures that interference from other gases is minimised.
In contrast to transmissive NDIR sensors, photoacoustic NDIR sensors measure the energy absorbed by CO2 molecules. When the infra-red emitter is pulsed, CO2 molecules absorb infrared light on a regular basis. This causes additional molecular vibration, which results in a pressure wave within the measurement chamber. The higher the concentration of CO2, the more light is absorbed, and thus the amplitude of the acoustic wave increases. A microphone inside the gas chamber detects this, and the CO2 concentration can then be calculated. Photoacoustic NDIR sensing allows for much more miniaturisation of the measurement chamber. Furthermore, because sound waves are omnidirectional, the relative position of the emitter and microphone is unconstrained. Thus, photoacoustic NDIR sensors are typically more mechanically and thermally robust.
The self-calibrating algorithm ABC logic is enabled by default. This algorithm is designed to be used in applications where CO2 concentrations drop to outside ambient conditions (400 ppm) at least once (15 minutes) in a 7-day period, which is typically seen during unmanned periods. The sensor reaches its operational accuracy after 25 hours of continuous operation at a condition where it is exposed to ambient reference levels of air with 400 ppm ± 10 ppm CO2.
Surface mounting sensor installed on wall socket
This sensor can be installed indoors on a wall or on a surface. The mounting holes are adapted to standard European wall mounting boxes. The sensor can be attached to the wall mounting box with two screws. The sensor enclosure will cover the entire wall mounting box. To ensure optimal performance, the sensor should be protected from direct sunlight.
Enclosure with contemporary design
The enclosure is designed for indoor use. It offers an IP30 protection against ingress of dust and moisture. The enclosure is exceptionally strong thanks to the use of high quality r-ABS plastic. Thanks to its contemporary modern design, this sensor can be used in most interior styles.
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