How do gas fireplaces vent?

The majority of our gas fireplaces and inserts are direct vent (DV). This means they have a fixed glass front which seals the gas burner and combustion firebox off from your home. 100% of the combustion air used by the fireplace comes from outside the home through a coaxial pipe. A smaller pipe inside the larger pipe eliminates all combustible gases, maintaining indoor air quality. The vent can be run horizontally through an outside wall, or vertically through the roof, depending on your preference.