Direct Vent Gas Fireplaces
A Direct-Vent gas fireplace system uses two vent pipes. One draws air in from outdoors to support combustion. The other exhausts the by-products of combustion to the outside. The two vent pipes may be concentric (exhaust pipe within a larger diameter intake pipe) or co-linear (separate pipes of about the same size).
Combustion takes place inside a sealed chamber – with a fixed piece of glass on the front of the fireplace. Room air circulates around the combustion chamber, often assisted by a blower, to heat the room.
A DV system is often installed along an outside wall to simplify the vent run, but can also be installed elsewhere in the home and vented through the roof or inserted into an existing wood burning fireplace.