How Does a Chimney Work

Sure, a fireplace is warm and romantic, but how does a chimney work to keep your house from filling with smoke? Fireplace smoke can be irritating and downright dangerous. A chimney makes it possible to enjoy a fire, while limiting the dangers of smoke inhalation.

How Does A Chimney Work Anyway?
When you start a fire in your fireplace, the combustion that produces the romantic warmth and flickering light also produces a large volume of smoke and toxic gasses. It is the job of the chimney to carry the noxious elements away. Here's how it happens:

• Types of chimneys. There are two types of chimneys commonly used in fireplace and stove installations: masonry and manufactured. Masonry chimneys are constructed of brick, concrete or stone-you know, the ones Santa comes down. Manufactured chimneys are created from metal pipe (typically stainless steel). Inserting one pipe inside another is the basic design of a manufactured chimney-the open space between the pipes is insulated with air or a non-flammable material.
• It's what's inside that counts. Masonry chimneys contain one or more vertical passageways called a flue. The flue is the conduit that transports the smoke and hot gasses up and away from the fireplace. Flues can be made of many materials including terra cotta pipes, ceramic cylinders or metal pipes.
• That really sucks. Once simple rule governs the use of a chimney: hot air rises. Well, two simple rules: as air moves, more air must fill in the gap. As your lovely fire heats the air, it travels up the chimney, creating a partial vacuum that carries away smoke and gas. Fresh air from outside and inside your home replaces the air going up the chimney.
• I need some air. Today's well-insulated, "tight" homes pose a challenge to the proper operation of a chimney. If your chimney isn't as efficient as it should be, try partially opening a window on the same floor as the fireplace to increase airflow.
• Clean and safe. Over time, a chimney will develop a coating of soot and creosote on its interior surface. This coating restricts airflow and could lead to a dangerous fire if not cleaned regularly by an experienced chimney sweep.