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AQ-Alert+ CO2 Air Quality Monitor

The AQ-Alert+ CO2 Air Quality Monitor is designed to monitor and control indoor air quality in the home, workplace, hotels and public areas resulting in benefits such as improved comfort and health.

Developed with flexibility in mind, the wall mounted AQ-Alert+ is a gas monitoring system capable of measuring carbon dioxide and oxygen levels. In addition to these two gases, the system can be fitted with sensors to measure temperature, barometric pressure and relative humidity. The customer can choose any combination of these five sensing options depending on their needs.

A variety of audio, visual, analog, serial communications and relay outputs are available to choose from.

If the application requires it, SST can integrate other gas sensors (e.g. carbon monoxide) into the AQ-Alert+.

With appropriate configuration, the AQ-Alert+ can operate in three modes:

Stand alone – The AQ-Alert+ CO2 Air Quality Monitor, monitors the air quality and alerts the occupant when a change in room conditions occurs. This can be via “traffic light” LEDs or a buzzer.
Direct control – The AQ-Alert+ monitors the air quality and directly controls ventilation, heating or air conditioning equipment in order to maintain a preset range of room conditions. Direct control is achieved via relays or analogue outputs in the AQ-Alert+ CO2 Air Quality Monitor.
Integration into a building management system – The AQ-Alert+ sends air quality data to another system that controls ventilation, heating or air conditioning. Multiple units can be individually configured and used throughout an entire system. Data is transmitted via analog or serial communications outputs.


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Part Numbering Guide


Supply Voltage (Vs) 24Vdc +/-10%
Current Consumption¹ 250mA max.
Sensors (up to five) CO₂
Temperature (T)
Relative humidity (Rh)
Atmospheric pressure (P)
Analogue Output (up to three) 4-20mA; load 500Ω max.
0-5Vdc; load 10kΩ max.
0-10Vdc; load 10kΩ max.
1-5Vdc; load 10kΩ max.
Communications (one) RS232
or RS485 (Modbus RTU)
Relay Outputs (up to three) 37.5VA, 250Vac max.
Alarms Visual: LEDs; traffic light sequence
Audio: Buzzer; 70dB at 4kHz


Sensor Measurement Range Accuracy Resolution
O₂ 0-25%² 1% vol.O₂ 0.01% vol. O₂
CO₂ 0-5000ppm
+/-5% of reading³
Temperature 0-50⁰C +/- 2⁰C 0.1⁰C
Humidity 0-95% Rh non-condensing +/- 3% 0.1%
Pressure 750-1150mbar Rh +/- 5 mbar 1mbar



¹All possible sensor and output options fitted.
²Prolonged operation below 0.1% O₂ will damage the sensing element.
³Whichever is greater.


  • Monitors and controls air quality in any building
  • Multi-gas monitoring system
  • Wall mounted design
  • Can be operated in three modes; stand alone, direct control or integrated into a building management system
  • Designed to measure CO₂ and O₂ with options to also measure temperature and humidity and other gases on request


  • Maintenance free
  • Customer specified outputs (voltage, current, relays, RS2332, RS485 Modbus)
  • Standard or customer specific alarm levels
  • Self calibrating
  • This field is for validation purposes and should be left unchanged.