Can a single flue be used for more than one heating system?

The use of a single flue for more than one heating system is generally not permissible due to safety, efficiency, and regulatory considerations. Each heating appliance typically requires its own dedicated flue system to effectively remove exhaust gases and ensure proper ventilation.

When multiple systems share a single flue, there is a heightened risk of backdrafting, where exhaust gases from one system can flow back into another unit or into the living space, leading to dangerous situations, including the potential buildup of carbon monoxide.

Building codes and safety standards reflect these concerns by often prohibiting shared flue systems to maintain clear pathways for exhaust removal and to minimize risks associated with combustion appliances. Therefore, the requirement for separate flues promotes both safety and compliance with regulations that govern heating systems.