A HVAC duct damper is a device used to control the flow of air within a heating, ventilation, and air conditioning (HVAC) system. It is typically installed in the ductwork of the system and is used to regulate the amount of air that is allowed to pass through the ducts. The damper is usually controlled by a motor, which is connected to a thermostat or other control device. The motor opens and closes the damper in response to changes in temperature or other environmental conditions. This allows the HVAC system to adjust the amount of air that is circulated in the building, ensuring that the desired temperature is maintained. Dampers are also used to control the flow of air in order to reduce noise, improve energy efficiency, and prevent drafts. In addition, dampers can be used to direct air to certain areas of the building, such as the bedrooms or living room. By controlling the flow of air, HVAC duct dampers help to ensure that the building is comfortable and energy efficient.