What type of duct is considered acceptable for combustion air supply in this context?

In the context of combustion air supply, round ducts are widely regarded as an acceptable option due to their ability to facilitate efficient airflow. The circular design minimizes resistance as air moves through the duct, promoting better distribution and volume. This efficiency is critical in applications where proper combustion and ventilation are paramount, such as in heating systems.

Round ducts also tend to have fewer seams than square or rectangular ducts, reducing potential leakage points which can compromise air quality and system efficiency. Additionally, the structural integrity of a round duct is often superior, which helps in maintaining consistent airflow under varying operational conditions.

While other types of ducts, such as square, flexible, or sheet metal ducts, can also be used in various applications, they may introduce inefficiencies or limitations in airflow management when specifically considered for combustion air supply. Therefore, round ducts stand out as a preferred choice in ensuring a reliable and effective combustion process.