How It Works

A natural gas or propane fireplace provides the warmth and distinctive beauty of a natural fireplace without the mess associated with wood, pellets or coal. Gas fireplaces come in three basic configurations: natural vent, direct vent and vent free.  

In a natural vent fireplace, the chimney is combined with a double wall pipe - known as a B-vent flue - which runs from the fireplace to the exterior of the home. Some models use a firebox or fireplace insert inside the larger fireplace to retain more heat and reduce energy cost.

Direct vent fireplaces draw air from outside and return exhaust outdoors with a flue system. Vents leading to the outdoors can be installed behind the fireplace so there’s no need for a chimney. This tightly sealed design only uses air from the outside for superior energy efficiency. The airtight system also works to prevent harmful emissions from entering the room.

Vent-free fireplaces are the easiest to install and operate; they vent exhaust straight into the room so there’s no need for a chimney or direct vent system. However, the main disadvantage of this type of fireplace is the potential for carbon monoxide (CO) buildup in the air. Excess CO can be seriously or fatally harmful if the person affected is not removed to an area with normal oxygen and CO content in the air. To minimize this danger, vent-free systems have an oxygen-detection feature that shuts the fuel gas off when the room’s oxygen level becomes hazardous.

What Can Go Wrong?

Many gas fireplaces use a small blower to move air and improve heating efficiency. These blowers are powered by motors that can fail over time.

Environmental Impact

Gas fireplaces burn cleaner and more efficiently than wood-burning fireplaces, operating between 12,000 and 60,000 British Thermal Units per hour (BTUh). Depending on usage and energy efficiency, they can produce hundreds of pounds of carbon dioxide (CO₂) annually.