What does a thermostat do in an HVAC system?

A thermostat plays a critical role in an HVAC system by regulating the indoor temperature. It acts as the primary control device that measures the ambient air temperature and compares it to the setpoint desired by the user. When the indoor temperature deviates from this setpoint, the thermostat signals the heating or cooling system to activate or deactivate, ensuring a comfortable environment by maintaining the desired temperature level.

The function of a thermostat is central to the overall operation of the HVAC system, as it directly impacts energy efficiency and comfort levels within a space. By continually monitoring temperature changes and adjusting the system accordingly, the thermostat helps to prevent overheating or overcooling, which can lead to increased energy consumption.

Other options, while essential functions in an HVAC setup, do not accurately describe the role of a thermostat. Air filtration, for example, is typically performed by filters within the HVAC system, enhancing indoor air quality rather than regulating temperature. Enhancing refrigerant flow is a function related to components like compressors and expansion devices, which manage how refrigerants move through the system, but this is also outside the thermostat's responsibilities. Lastly, air distribution is managed through ductwork and fans, ensuring that conditioned air reaches all areas within a space, rather than being controlled by the thermostat itself.