A round duct is a circular air passage used in HVAC (Heating, Ventilation, and Air Conditioning) systems to distribute air throughout a building. Its round shape allows air to flow smoothly with less resistance, making it more energy-efficient compared to rectangular ducts.

In addition to providing efficient airflow, round ducts also help reduce air leakage and noise within the system. They are often used in both residential and industrial settings due to their durability and ease of installation. Overall, the round duct plays an essential role in maintaining good air circulation and consistent temperature control in any HVAC system.