A Direct-Vent 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 glass front in the 
case of a 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.

Advantages:

• Good efficiency – 60 to 80%
• Good heat output with thermal transfer through the glass and air circulation
• Separates room air from combustion air
• May be used as primary heat source
• Can operate with a remote or thermostat
• Most systems can provide life-saving heat during a winter power outage
• Choose fireplace, insert, cast iron stove, or heater