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  • New item   Room VOC sensor | 4–20 mA, 0–10 V DC, Modbus RS485 | indoor air quality measurement

    Room VOC sensor | 4–20 mA, 0–10 V DC, Modbus RS485 | indoor air quality measurement

    Code: SKU#165269503298491561
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    Price 133.10 € VAT incl.
    ( 110.00 € VAT excl. )
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    Wall-mounted VOC sensor that measures indoor air pollution by volatile organic compounds. It transmits the signal via 4–20 mA, 0–10 V DC or Modbus RS485 for demand-controlled ventilation.

  • Product description

    Room VOC sensor with 4–20 mA, 0–10 V DC and Modbus RS485 outputs

    The room VOC sensor measures the level of volatile organic compounds (VOC) in indoor air and converts it into a standard control signal. It is wall-mounted in the zone where people spend most of their time. It has three outputs – 4–20 mA, 0–10 V DC and Modbus RS485 – so it connects to a heat recovery unit or AHU controller, a PLC or a building management system (BMS).

    ⚠ Measuring range, supply voltage and Modbus register map are not stated in this description – check them in the supplier datasheet delivered with the product before wiring.
    Key point:
    A VOC sensor lets you ventilate according to actual air pollution instead of a timer. When odours, cleaning agents, paints or emissions from furniture increase, the signal rises and the controller increases the airflow. When the air is clean, the fans slow down and heating and electrical energy is saved. Three output types let you use the same sensor in a simple analogue system and in a networked one.
    Measures
    VOC (air quality)
    Analogue outputs
    4–20 mA / 0–10 V DC
    Digital interface
    Modbus RS485
    Mounting
    Wall

    Operating principle

    VOC is a collective name for many volatile organic substances: solvents, odours, cleaning agents and compounds released by human activity. Sensors of this type typically use a semiconductor (metal oxide) sensing element whose resistance changes when oxidisable gases reach its surface. The electronics convert this change into an air quality value.

    The result is provided in three ways: a 4–20 mA current signal (robust over long cables and against interference), a 0–10 V DC voltage signal (suits most ventilation controllers and frequency inverters) and Modbus RS485 (digital communication when several sensors share one bus).

    A VOC sensor does not distinguish individual substances and does not measure CO₂ directly – it shows the overall trend of air pollution. That is exactly what demand-controlled ventilation (DCV) needs.

    Why use a VOC sensor?
    It reacts to what people perceive as stuffy or smelly air, even when the CO₂ level is still normal: after cleaning, renovation, cooking or in rooms with new furniture. Ventilation is boosted only when it is really needed.

    Technical specifications

    Product type Room VOC sensor
    Measured quantity Volatile organic compounds (VOC), overall air quality value
    Mounting Wall-mounted indoors
    Analogue current output 4–20 mA
    Analogue voltage output 0–10 V DC
    Digital interface RS485, Modbus protocol
    Measuring range, supply, Modbus registers According to supplier datasheet

    Main functions

    • 4–20 mA output – stable signal over long lines, a broken wire is easy to detect (0 mA).
    • 0–10 V DC output – direct connection to the analogue input of ventilation controllers, EC fans or frequency inverters.
    • Modbus RS485 – several sensors on one bus, data straight to a PLC or BMS.
    • Overall VOC value – reacts to odours, solvents, cleaning agents and human activity.
    • Demand-controlled ventilation – fan speed follows the actual air pollution.
    • Energy saving – heated or cooled air is not exhausted unnecessarily.
    • Wall mounting – measures where people breathe.
    • Versatility – the same sensor suits both analogue and networked systems.

    How does it differ from similar products?

    CO₂ sensor measures carbon dioxide only (occupancy); a VOC sensor also reacts to odours, solvents and cleaning agents.
    Gas leak detector designed to detect hazardous concentrations and raise alarms; a VOC sensor is for comfort and ventilation control.
    Duct VOC sensor measures the average of extract air in the duct; the room version measures in a specific room.

    Where is it used?

    • Offices and open-plan spaces
    • School classrooms and kindergartens
    • Meeting and conference rooms
    • Flats and houses with heat recovery ventilation
    • Hotel rooms
    • Gyms and changing rooms

    Use by experience level

    Beginner.
    The simplest option is to connect the 0–10 V DC output to the analogue input of a heat recovery unit or ventilation controller – only supply and signal wires are needed.
    Advanced installer.
    Use 4–20 mA for long lines, and connect several sensors via a Modbus RS485 bus using shielded twisted-pair cable.
    Energy engineer / designer.
    Combine the VOC sensor with a CO₂ sensor: CO₂ indicates occupancy, VOC indicates other pollutants. The DCV system then responds to both.

    Practical application

    An office meeting room is ventilated by a heat recovery unit. The sensor's 0–10 V DC output is connected to the analogue input of the unit's controller: when the VOC level rises after a meeting or cleaning, the controller increases fan speed, and returns to minimum mode when the room is empty.

    Pros / advantages

    • Three output types in one sensor
    • Suitable for demand-controlled ventilation (DCV)
    • Reacts to odours and solvents that a CO₂ sensor does not see
    • Easy integration into a PLC or BMS via Modbus
    • 4–20 mA signal suits long lines
    • Measures directly in the occupied zone

    Cons / limitations

    • Shows the overall VOC level, does not identify individual substances
    • Does not measure CO₂ – a CO₂ sensor is needed to assess occupancy
    • Semiconductor VOC sensors usually need a warm-up time after power-on
    • Range and supply must be confirmed from the supplier datasheet

    Safety and installation notes

    • ⚡ Carry out wiring with the control panel supply disconnected; installation by a qualified electrician.
    • ⚠ Before wiring, check the supply voltage and output type against the datasheet – a wrong voltage can damage the electronics.
    • ⚠ Use shielded twisted-pair cable for the RS485 line and termination resistors at the bus ends as required by the system.
    • ⚠ A VOC sensor is not a gas leak or explosion detector – do not use in explosive atmospheres without Ex certification.
    • ⚠ Do not mount near doors, windows, heaters or directly above printers – readings will be distorted.

    Quick selection guide

    VOC – air quality
    4–20 mA
    0–10 V DC
    Modbus RS485
    Suitable when you need to:
    • ventilate according to actual air pollution
    • react to odours, solvents and cleaning agents
    • send an analogue or Modbus signal to a controller
    • measure in a specific room
    Check before choosing:
    • supply voltage and current consumption
    • measuring range and how it is scaled to 4–20 mA / 0–10 V
    • Modbus address, baud rate and register map
    • mounting location and height in the room
    Important reminder: A VOC sensor does not replace a CO₂ sensor or a gas leak alarm: it is intended for comfort and demand-controlled ventilation.
    ☝ Elsprendimai.eu recommends:

    FAQ

    How does a VOC sensor differ from a CO₂ sensor?
    A CO₂ sensor shows how much exhaled air has accumulated in a room. A VOC sensor reacts to odours, solvents, cleaning agents and other organic compounds.
    Which output should I choose – 4–20 mA or 0–10 V DC?
    For long lines and noisy environments – 4–20 mA. When the controller is close and has a 0–10 V input – 0–10 V DC.
    Can Modbus and the analogue output be used at the same time?
    This depends on the specific device settings – check the datasheet.
    Does the sensor detect gas leaks?
    No. It is an air quality sensor for ventilation control, not a safety detector. It must not be used in explosive atmospheres without Ex certification.
    Where can I find the Modbus register map?
    It is provided in the supplier datasheet. If you do not have it, contact us – we will help you get it.
    How long does it need after power-on?
    Sensors of this type usually need a warm-up time before readings stabilise. The exact time is stated in the datasheet.

    Sources: Manufacturer not identified (supplier product). Parameters based on the product name and general VOC sensor operating principles; measuring range and supply according to the supplier datasheet. Checked 2026-10-18.

    Room VOC sensor for demand-controlled ventilation

    The room VOC sensor measures indoor air quality and transmits the signal via 4–20 mA, 0–10 V DC or Modbus RS485. It suits offices, schools and homes with heat recovery ventilation, where ventilation must respond to actual air pollution.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

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