A CO2 sensor is an important component of any HVAC system. It is used to measure the amount of carbon dioxide in the air, which is an important indicator of air quality. The sensor is typically installed in the return air duct of the HVAC system, and it monitors the CO2 levels in the air. If the levels become too high, the sensor will trigger an alarm to alert the occupants of the building. The alarm will also alert the HVAC system to increase the ventilation rate to reduce the CO2 levels. This is an important feature of any HVAC system, as it helps to maintain a healthy indoor air quality. The CO2 sensor is also used to adjust the temperature in the building, as higher CO2 levels can lead to an increase in the temperature. By monitoring the CO2 levels, the HVAC system can ensure that the building remains comfortable and safe for its occupants.