Many models of Bryant furnaces, such as the Bryant 915S Legacy gas furnace, can be used without a chimney. These furnaces operate using a direct-vent system where exhaust gases can be directed through plastic pipes to a building's exterior instead of through a chimney.
Direct-vent furnaces produce much cooler exhaust gases than non-direct vent models, allowing them to bypass the need for a vertical exhaust chimney. In addition, most direct-vent furnaces are far more efficient than older designs. In the most efficient designs, they turn up to 95 percent of the energy contained in the furnace's fuel into useful heat for a building.