Direct vent kits include two pieces of aluminum flex pipe, one for exhaust and the other for air intake. Some vent kits also contain a cap to cover the end of the vent. Furnaces, fireplaces and hot water heaters use direct vent systems when other ventilation options are not available.
Direct vent systems are easier to install than chimney systems, since no extra masonry or foundation is necessary to add it to the home. Direct vents make complete remodels unnecessary for people who want a fireplace. Some direct vent systems offer greater efficiency than traditionally vented heating appliances. The direct vent system pulls air involved in combustion from outside and uses all of its gases, so there is no lost heat as is typical of a larger chimney.
In a traditional fireplace, hot air rises to the top due to the convection effect. This elevates the volume of exhaust gases that the combustion process generates and strains the inner flue as more gas tries to escape. Carbon monoxide can accompany heated air as it enters the room from the firebox. Direct vent fireplaces exhaust the carbon monoxide instead of allowing it into the room. Many consumers choose direct venting because of energy efficiency and reduced emissions into living areas.