What is the passage in a masonry chimney used for smoke and gas exit known as?

The passage in a masonry chimney specifically designated for the exit of smoke and gases is known as a flue. This term refers to a duct, pipe, or opening that allows byproducts of combustion to safely vent outside, ensuring proper function of heating systems and maintaining indoor air quality.

The flue is critical in regulating the flow of gases and protecting the structural integrity of the chimney; it also plays an important role in preventing backdrafts, which can lead to dangerous conditions within a building. In masonry chimneys, a well-designed flue is essential for effective ventilation, making it a key component of safe heating appliance operation.

Understanding the function of the flue is vital for anyone working with masonry and chimney construction, as it directly impacts safety and efficiency in venting combustion products.