What is the role of a chimney cap?

A chimney cap serves several important roles, with one of its primary functions being to prevent animals and debris from entering the flue. When a chimney cap is properly installed, it acts as a protective barrier at the top of the chimney. This barrier keeps out birds, squirrels, and other animals that may try to enter and potentially build nests inside the chimney. Additionally, it prevents leaves, twigs, and other debris from falling into the flue, which could obstruct the chimney and lead to dangerous blockages.

While the other roles mentioned might appear relevant, they do not specifically address the main purpose of a chimney cap. For instance, improving draft relates to the design of the flue and airflow, whereas containing smoke is more associated with the chimney structure itself. Increasing heating efficiency typically requires other modifications and does not fall under the chimney cap's primary functions. Thus, the correct answer reflects the specific and crucial purpose of a chimney cap in maintaining a safe and functional chimney system.