How Fireplaces Work

Stylish wood-burning stone fireplace provides a central focal point in this contemporary living room.Attila / Shutterstock.com

Stylish wood-burning stone fireplace provides a central focal point in this contemporary living room.

Nothing quite matches the warmth and ambiance of flickering flames in a fireplace.

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Bold mantle draws attention to this simple wood-burning fireplace.

On a cold day, a fire is the perfect focal point for reading a good book or enjoying quiet conversation. But wood-burning fireplaces have fallen under scrutiny in recent years because of concerns about carbon output and pollution caused by particulates in their smoke.

Fortunately, conventional wood-burning fireplaces have evolved to mitigate some of the air pollution problems associated with them. Today a variety of options are available that produce heat with much less pollution.

Combustion appliances and fixtures such as fireplaces, wood stoves, pellet stoves, and furnaces must vent their smoke and other toxic combustion gases through a flue or chimney.

wood burning fireplace and chimney©Don Vandervort, HomeTips

Typical Masonry Fireplace Construction

Chimneys are designed to capture and carry smoke and hot gases up and away. To pull smoke and gasses away by natural convection, a chimney is typically tall—from fireplace to a couple of feet above the roof.  Though traditional chimneys vent out the roof, some of today’s high-efficiency fireplaces and other combustion appliances can vent out through a wall.

Conventional chimneys have traditionally been built of brick and mortar, lined with fireproof flue tiles, and capped with mortar to seal the top against weather. But today, newer, easier-to-install types of chimneys are made of metal and sold as prefabricated kits. These are much easier to build and, in the event of an earthquake or other disaster, are less likely to fall.

Brick Chimney Construction©Don Vandervort, HomeTips

Brick Chimney Construction

Most chimneys handle their important job admirably, but a chimney that is in disrepair or is ill-maintained not only wastes energy but can also be a safety hazard.

In the case of combustion fireplaces, at the same time that smoke and combustion gasses are vented away from interior living areas through a flue or chimney, oxygen-filled combustion air is drawn into the burning chamber.

©Don Vandervort, HomeTips

Here you can see the main parts of a fireplace’s facade.

Unless a fireplace has glass doors and a vent that draws combustion air from outdoors, it can extract more warmth from a home than it delivers. Those same convection currents that carry smoke up the chimney can also pull expensively-heated interior air from the room, sending it out through the chimney.

A fireplace’s hearth and facade may be made of brick, rock, concrete, marble, granite, tile, or other related, non-combustible materials. Codes and common sense restrict how close to the opening combustible materials—such as wood paneling, wood flooring, or wallboard—may be located.

The rest of the fireplace may be constructed in a variety of ways, depending upon the type. On the following pages,  you can see the typical anatomy of a masonry and zero-clearance manufactured fireplace.

NEXT SEE:

Masonry Fireplace & Chimney Anatomy
Fireplaces Buying Guide
Chimney Repairs

Featured Resource: Find a Pre-Screened Local Fireplace Pro


Fireplaces & Chimneys

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