Chimney Safety Institute of America (CSIA) Certification Practice Test

Which of the following is a common sign of chimney blockage?

1. Increased draft

2. Low heating efficiency

3. Odorless operation

4. Visual clarity through the flue

The correct answer is: Low heating efficiency

A common sign of chimney blockage is low heating efficiency. When a chimney is obstructed, it can lead to insufficient airflow, which affects the system's ability to exhaust combustion gases efficiently. This blockage can cause an excessive buildup of carbon monoxide and other gases, leading to poor heating performance because the fire cannot draw in enough air to burn fuel effectively. Homeowners may notice that despite their heating system running as usual, the space does not warm up as expected, which is directly tied to the chimney's compromised ability to facilitate proper ventilation. In contrast, options like increased draft, odorless operation, and visual clarity through the flue do not indicate blockage. Increased draft typically suggests that air is flowing well, enabling efficient operation, while odorless operation can be a sign of adequate ventilation rather than blockage. Visual clarity through the flue indicates that there are no obstructions in the chimney, which contradicts the signs of blockage.