Vaillant VAZ CO/1 - air quality sensor (CO2) for recoVAIR

Product detailed description

Vaillant VAZ CO/1 - air quality (CO2) sensor for recoVAIR heat recovery units

Vaillant VAZ CO/1 (manufacturer part number 0020184869, also listed by some distributors as "VAZ CO2/1") is a wall-mounted air quality sensor that measures the carbon dioxide (CO2) concentration in a room and automatically controls the output of the recoVAIR heat recovery unit (models VAR 150/4, VAR 260/4 and VAR 360/4) based on the measured values. Instead of manually switching between output levels, as is the case with the simpler VAZ S4/1 controller, this sensor ensures the unit ventilates exactly as much as is actually needed at any given moment - more when the room occupancy is higher (for example during a visit, family celebration, or an evening in front of the TV with several people) and less when there are fewer people in the room or it is empty.

This principle is known as demand-controlled ventilation (DCV) and its main benefit is the optimal balance between indoor air quality and energy efficiency of operation - the unit does not run unnecessarily at a high output level (and therefore with higher power consumption and noise) when it is not needed, but automatically "ramps up" as soon as the CO2 concentration in the room exceeds the recommended threshold for a healthy indoor environment.

Technical characteristics

• Sensor type: capacitive polymer CO2 sensor (non-dispersive CO2 concentration measurement principle)
• Manufacturer order number: 0020184869
• Measured CO2 concentration range: 0 - 2,000 ppm
• Output signal: analog, 0 - 10 V (proportional to the measured CO2 concentration)
• Supply voltage: 20 - 24 V AC, connection via screw terminal block
• Installation: wall-mounted, in a living room (recommended height approximately 1.4 - 1.7 m, away from direct airflow from ventilation grilles, doors or windows)
• Maximum number of sensors per system: 2 pcs (allows monitoring air quality in multiple rooms simultaneously, e.g. in the living room and bedroom)
• Compatibility with controllers: works with the calorMATIC 470/4 system controller and the control electronics of recoVAIR /4 generation units
• Compatible units: recoVAIR VAR 150/4, VAR 260/4, VAR 360/4 (including "E" variants with an enthalpy exchanger)
• Housing material: plastic, design matching other Vaillant control elements
• Country of origin: Germany / EU (Vaillant Group)
• Warranty: 2 years

Operating principle

Carbon dioxide (CO2) is one of the most reliable indirect indicators of air quality in occupied spaces - its concentration rises directly in proportion to the number of people in a room and the length of their stay, since CO2 is produced through breathing. Outdoor air typically contains around 400 - 450 ppm of CO2, while in a closed, unventilated room with several people the concentration can quickly rise to 1,000 - 2,000 ppm or more, resulting in a feeling of "stuffy," heavy air, fatigue, reduced concentration, and poorer sleep.

The VAZ CO/1 sensor continuously measures the CO2 concentration at its installation location using a capacitive polymer sensor and converts the result into an analog 0 - 10 V signal, which is passed to the control electronics of the recoVAIR unit (or via the calorMATIC 470/4 system controller). The unit's electronics then automatically increase or decrease the fan output, without any user intervention, so that the CO2 concentration is maintained within the recommended, healthy range. Thanks to the option to connect up to two sensors simultaneously, it is possible to monitor air quality in two different rooms (for example, the bedroom at night and the living room during the day), and the unit responds to the higher of the measured values, ensuring sufficient ventilation throughout the entire apartment/house.

Installation and wiring

The sensor is mounted on a wall in the location where monitoring air quality is most desirable - most often in the living room, bedroom, or the room with the highest expected occupancy. It is important to avoid placing it near ventilation grilles, open windows, exterior doors, or heat sources (radiator, fireplace), as airflow from these sources could distort the measured value. The recommended installation height is approximately 1.4 to 1.7 m above the floor, i.e. within the zone where an adult's breathing zone is typically located.

Electrical connection requires a 20 - 24 V AC power supply and connection of the signal wire to the control electronics of the recoVAIR unit or to the calorMATIC 470/4 system controller, according to the specific wiring diagram given in the installation manual for the particular unit model. Since this involves a low-voltage but functionally sensitive connection directly to the control electronics of the heating/ventilation system, we strongly recommend entrusting the installation and parameter setting (e.g. the target CO2 threshold value at which the output should increase) to a trained technician or an authorized Vaillant service partner.

Compatibility and use in the system

The VAZ CO/1 is designed for the entire recoVAIR /4 generation range (VAR 150/4, VAR 260/4, VAR 360/4), including variants with an enthalpy exchanger. It brings the greatest benefit in combination with the calorMATIC 470/4 system controller, which can process the signal from up to two sensors simultaneously and intelligently evaluate which room currently has the highest ventilation demand. In smaller apartments with one main living zone, a single sensor is sufficient, while in larger family houses with a separate bedroom and living room, it is worth considering the installation of two units for more precise and comfortable control.

The sensor can also be combined with other recoVAIR accessories - for example, an electric air pre-heater (protecting the exchanger from freezing in winter) or a higher filtration class (F9/G4 for polluted environments), since these components address different system functions (frost protection and filtration) and do not affect the way output is controlled based on CO2. On the other hand, combining it with the simple VAZ S4/1 controller in a single installation is not typical, as both components address the same function (output control) in different ways - the CO2 sensor automatically, the controller manually.

Why choose demand-controlled ventilation with a CO2 sensor

Investing in an air quality sensor is particularly worthwhile in households that place emphasis on maximum comfort and automation, or where the number and distribution of people in individual rooms changes significantly throughout the day (for example, families with children, households with a home office, or spaces with occasional larger numbers of visitors). Automatic control based on actually measured air quality can respond more precisely and quickly than any fixed time schedule, while also saving energy, as the unit does not run unnecessarily at high output when the current room occupancy does not require it.

The health aspect is also not negligible - several indoor climate studies link long-term elevated CO2 concentrations (above 1,000 - 1,500 ppm) with reduced concentration, headaches, and poorer sleep quality. Automatically maintaining a lower CO2 concentration thanks to the VAZ CO/1 sensor therefore brings a real benefit to the well-being and health of household occupants, not just energy savings.

Maintenance and care

Capacitive polymer CO2 sensors are inherently long-term stable devices that require no maintenance from the user during normal operation. We only recommend keeping the area around the sensor free of obstacles (furniture, curtains, decorations) that could hinder free airflow to the sensor and thus distort the measurement. The surface of the sensor can occasionally be wiped with a slightly damp cloth without the use of aggressive or abrasive cleaning agents.

If you suspect incorrect operation (for example, the unit constantly runs at maximum output even with low room occupancy, or conversely does not respond at all to increased CO2 concentration), we recommend contacting an authorized Vaillant service center, which can verify the correctness of the wiring, the sensor calibration, and the threshold values set in the control electronics.

Why choose this sensor

The Vaillant VAZ CO/1 is an original accessory directly from the manufacturer of recoVAIR units, designed and tested to work seamlessly with the unit's control electronics as well as with the calorMATIC 470/4 system controller. Compared to universal third-party sensors, it therefore provides assurance of correct communication with the system, preservation of the warranty conditions for the entire device, and simple future service support directly from the Vaillant brand.

Frequently asked questions

How many VAZ CO/1 sensors can be connected to one recoVAIR unit?

The system supports connecting up to two sensors simultaneously, allowing air quality to be monitored in two different rooms, with the unit responding to the higher of the measured CO2 values.

What is the measured CO2 concentration range?

The sensor measures CO2 concentration in the range of 0 - 2,000 ppm, and the output is an analog 0 - 10 V signal proportional to the measured value.

Can the sensor be combined with the VAZ S4/1 controller?

This is not a typical combination - both devices address the same function (controlling the unit's output) in different ways, so in practice either one or the other solution is chosen depending on the desired level of automation.

Where is the best place to install the sensor?

In the living room with the highest expected occupancy, away from direct airflow from windows, doors, or heating elements, at a recommended height of approximately 1.4 - 1.7 m above the floor.

Does the sensor need regular calibration?

Normal operation does not require calibration by the user. If you suspect incorrect measurement, we recommend contacting an authorized Vaillant service center, which will check and, if necessary, recalibrate the sensor.

Which recoVAIR models is the sensor designed for?

It is compatible with the entire /4 generation range - VAR 150/4, VAR 260/4, VAR 360/4, including variants with an enthalpy exchanger (marked "E").

What is the supply voltage of the sensor?

The sensor is powered by 20 - 24 V AC connected via a screw terminal block.

What is the warranty on this sensor?

We provide a standard 2-year warranty on the VAZ CO/1 sensor, the same as for other accessories and parts for Vaillant recoVAIR units.

Comparison of recoVAIR unit output control solutions

Recommended CO2 threshold values and their effect on indoor well-being

Maintaining the CO2 concentration below approximately 1,000 - 1,200 ppm is generally the recommended target for a healthy indoor environment in residential buildings. The VAZ CO/1 sensor achieves this target automatically by continuously adjusting the fan output of the recoVAIR unit to the currently measured value, without requiring any intervention from the household occupants.

Typical household usage scenarios

• Family with children: children's rooms and bedrooms have higher occupancy per square meter at night than, for example, a home office during the day - the sensor automatically increases the unit's output when the rooms are occupied and decreases it when they are empty.
• Household with a home office: an office where one or more people spend long periods during the day benefits from continuous automatic ventilation without the need to manually check and switch the unit's output.
• Occasional visits and family celebrations: when the number of people in the living room increases, the sensor quickly detects the rise in CO2 and increases the ventilation output before occupants or guests even notice the unpleasant feeling of "stuffy" air.
• Apartments with limited window ventilation options: for example, apartments facing a busy street, where residents avoid frequent window ventilation due to noise or pollution - automatic CO2-based control ensures the necessary air exchange without having to compromise between air quality and noise/dust from the surroundings.

The relationship between air quality, energy savings and unit lifespan

Demand-controlled ventilation brings benefits not only in terms of comfort and health, but also in terms of operating costs and the lifespan of the recoVAIR unit itself. The unit's fans do not run unnecessarily at high output when the current room occupancy does not require it, which reduces electricity consumption as well as mechanical wear on moving parts (fan bearings, bypass motor, or enthalpy exchanger motor, if the unit is equipped with one). At the same time, the noise load on the household is also reduced during the night hours, as the unit automatically reduces output to a quieter, more economical level when the measured CO2 concentration is low.

This combination of higher comfort, lower energy consumption and quieter operation is the main reason why the VAZ CO/1 air quality sensor is particularly recommended for projects where the investor places emphasis on long-term efficiency and living comfort, not just the initial purchase price of the accessory.

Summary

The Vaillant VAZ CO/1 is an original air quality sensor that transforms the recoVAIR unit from a simply adjustable ventilation device into a fully automated demand-controlled ventilation system. Through continuous measurement of CO2 concentration and automatic adjustment of fan output, it provides greater comfort, a healthier indoor environment, and more efficient energy management compared to fixed or manually switched output. We particularly recommend it for households that want to maximize the benefit of their investment in controlled ventilation with heat recovery without the need for manual intervention in daily operation. If you have any questions about choosing the most suitable combination of accessories for your specific project, please do not hesitate to contact our sales team.