Direct-vent fireplaces vent all byproducts of combustion outside. The fire burns inside a sealed combustion chamber that vents vertically or horizontally through a double wall pipe to the outside. All products of combustion are vented through the inner pipe outside while the space between the inner and outer pipe is bringing in air for combustion; therefore no internal air from the house is used. This type of fireplace is designed to operate efficiently and minimize heat loss. Typically speaking, the cost of the unit has a direct reflection on how realistic the fire looks, the visual and convenience options and level of efficiency. When choosing your direct fireplace you will have options to choose from such as a liner, logs, crushed glass and more. Direct vent fireplaces are available in traditional, linear and see-through models.