Factory-built chimneys shall be listed and labeled according to __________.

Factory-built chimneys are designed and manufactured to meet specific performance standards and safety requirements. The correct option emphasizes the importance of adhering to the manufacturer's installation instructions. These instructions provide detailed guidelines on how to properly install the chimney while ensuring it functions safely and effectively.

By following the manufacturer's specifications, installers can ensure that the chimney is compatible with the heating appliance it serves and operates within the intended safety parameters. This includes considerations like clearances to combustibles, venting configurations, and materials to be used during installation. Proper adherence to these instructions helps prevent issues such as improper venting, which could lead to hazardous conditions like carbon monoxide buildup.

While other considerations like local codes, national safety standards, and environmental regulations might impact the installation, the manufacturer's guidelines are critical for ensuring that the chimney performs safely according to its design. Manufacturers typically undergo testing and certification processes to ensure compliance with recognized safety standards, making the installation instructions a reliable source for maintaining safety and efficacy.