Which of the following is a common size for residential flue pipes?

A common size for residential flue pipes is 6 inches. This dimension is widely used in the installation of flue systems for heating appliances such as furnaces and water heaters. The 6-inch diameter effectively accommodates the venting needs for most residential applications, providing adequate space for exhaust gases to escape while maintaining the necessary draft for efficiency.

Understanding the sizing of flue pipes is crucial, as it directly impacts the performance of the appliance and the safety of the system. A flue that is too small may restrict airflow and compromise the appliance's operation, while one that is too large may fail to maintain the necessary draft. Therefore, adhering to standard sizing, such as 6 inches, ensures optimal performance and safety in residential plumbing systems.