No, absolutely not. A direct vent uses a high temperature glass panel to seal off the burn area of the fireplace from the interior of the home. It pulls 100% combustion air to feed the fire from outside the home. Because of its design, a direct vent gas fireplace will not affect the indoor air quality of your home. Since no air from your home is going up the chimney, a direct vent model is very efficient. Vent free should actually be called room vented since the by-products of gas combustion all spill back into the room. The single largest by-product of the gas combustion process is water vapor. Over sizing or overuse of a vent free hearth product can lead to excess moisture in a well built, tightly constructed home. Excess moisture inside the home can contribute to odors, mold and mildew inside the home.