NCIDQ IDFX Practice Exam

What is the purpose of a mixing box?

1. Adjust the quantity or temperature of air

2. Control the humidity level

3. Filter dust and debris from the air

4. Reduce sound within the ductwork

The correct answer is: Adjust the quantity or temperature of air

The purpose of a mixing box is to adjust the quantity or temperature of air that is supplied to a space. Mixing boxes are essential components of HVAC systems, as they take in air from multiple sources, typically both conditioned air from ducts and outside air, and then mix them to achieve the desired temperature and airflow. This process allows for better control over the indoor climate, which is crucial for maintaining comfort. The mixing box can regulate the amount of heated or cooled air flowing into a room based on current conditions, thereby enhancing energy efficiency and comfort levels. While controlling humidity, filtering dust and debris, and reducing sound levels are also important aspects of air quality and HVAC systems, they are typically managed by different systems or components within the overall system. For instance, humidity control is often achieved through the use of dehumidifiers or humidifiers, filtration is managed by air filters in the HVAC system, and sound attenuation may be achieved by using specific duct designs or sound-absorbing materials.