Which of the following components is identified as part of the secondary system in HVAC?

• A. Compressor
• B. Air Ducts
• C. Expansion Valve
• D. Thermostat

Answer: (B)

In HVAC systems, the secondary system refers to the components that distribute or utilize the conditioned air or refrigerant after it has been processed by the primary components, such as the compressor and evaporation coil. Air ducts are critical in this context as they are responsible for distributing air throughout the building after it has been cooled or heated by the primary system.

Air ducts function as the delivery mechanisms for warmed or cooled air generated in the HVAC system, ensuring that air reaches various rooms or areas. They are not involved in the initial conditioning process but play a significant role in the overall efficiency and effectiveness of the HVAC system by maintaining airflow and ensuring heat transfer occurs in different spaces.

Conversely, other components like the compressor and expansion valve are part of the primary system, involved directly in refrigerant circulation and thermal management. The thermostat serves as a control mechanism for the HVAC system, regulating the temperature but does not directly participate in the conditioning or distribution process itself.