What is the vertical passage for combustion products to the atmosphere called?

The vertical passage for combustion products to the atmosphere is correctly identified as having multiple terms that can describe it, including chimney, stack, and flue.

A chimney generally refers to the entire structure that extends above the roof of a building and serves to carry smoke and gases away from a fireplace or furnace.

A stack is commonly used in industrial contexts and refers to a tall, vertical structure designed specifically for the expulsion of flue gases from industrial processes or power generation.

A flue represents the duct or pipe through which combustion gases flow; it can be part of a chimney or stack and is important for directing these gases to the outside.

Each of these terms is used in specific contexts but ultimately serves the same fundamental purpose of removing combustion byproducts from a building or structure into the atmosphere. Therefore, recognizing that all three terms can accurately describe the vertical passage demonstrates an understanding of the terminology within the context of combustion and ventilation systems.