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

The primary function of a thermostat in an HVAC system is to regulate temperature settings. It acts as a control device that monitors the temperature of the environment and compares it to the desired temperature set by the user. When the ambient temperature deviates from this set point, the thermostat sends a signal to the heating or cooling system to either activate or deactivate to maintain a comfortable and consistent temperature indoors.

In this context, other options focus on different aspects of HVAC operation. Filtering dust from the air is a function associated with air filters rather than a thermostat, which does not perform any filtration tasks. Controlling humidity is typically managed by humidistats or specific HVAC systems designed for that purpose, while activating backup power is related to electrical systems rather than temperature regulation. Thus, the primary role of a thermostat is clearly centered on regulating temperature situations.