What is the minimum vertical distance for a mechanical air intake opening from a chimney or fuel-burning appliance vent?

The minimum vertical distance for a mechanical air intake opening from a chimney or fuel-burning appliance vent is 3 feet. This requirement is in place for safety and to ensure proper ventilation. Maintaining this distance helps prevent the possibility of exhaust from the chimney or venting system entering the mechanical air intake. If the intake is positioned too close to the vent, flue gases, which can contain harmful pollutants, may re-enter the building’s ventilation system, potentially leading to dangerous conditions such as carbon monoxide poisoning or reducing indoor air quality.

In terms of building codes and safety practices, the 3-foot separation is a standard that reflects a balance between ensuring adequate air quality and preventing backdrafting, which can occur when exhaust gases are pulled back into the living space instead of being vented outside.