What is the primary function of a thermostat in an HVAC system?

The primary function of a thermostat in an HVAC system is to control the temperature of the environment. It acts as the interface between the occupants' desired comfort level and the heating or cooling systems. When the temperature in a space deviates from the predetermined setpoint, the thermostat sends a signal to the HVAC system to either heat or cool the space until the desired temperature is achieved. This function is crucial for maintaining comfort and ensuring that energy is used efficiently.

While increasing system efficiency is a beneficial outcome of proper thermostat operation, it is not the primary function. Likewise, filtering out air pollutants pertains more to air filtration systems rather than the thermostat's role. Monitoring electrical supply is not related to temperature control; instead, that task falls under other system components focused on electrical management. Therefore, controlling temperature is the essential task that defines the thermostat's role within an HVAC setup.