What size masonry chimney is required for a 45-foot tall chimney in a commercial building with a 341,000 Btu input from a Category 1 natural draft vented appliance?

For a commercial building with a 341,000 Btu input from a Category 1 natural draft vented appliance, the correct size for a masonry chimney is determined by several factors, including the height of the chimney, the appliance input, and the specific requirements outlined in relevant codes and standards.

In this case, a 45-foot tall chimney is significant; as chimneys get taller, they must accommodate the increased draft required for proper venting of combustion gases from high-efficiency appliances. Category 1 appliances typically require a chimney that ensures sufficient draft for effective exhaust of flue gases.

An 8-inch chimney size is appropriate for this input level and height, providing the necessary capacity for exhaust gases and ensuring that the chimney can maintain a proper draft throughout its height. Additionally, code requirements such as those found in the National Fuel Gas Code or local building regulations will specify dimensions based on these parameters, confirming that an 8-inch chimney adequately meets the needs of a 341,000 Btu input in a tall configuration like 45 feet.

Understanding the impact of chimney diameter on draft performance and adhering to standardized construction guidelines are crucial for safely and efficiently venting gas appliances. This attention to detail minimizes risks associated with improper ventilation, such as exhaust