What is the requirement for spacing regarding existing interior and exterior chimneys when replacing oil or gas fired appliances?

When replacing oil or gas-fired appliances, the requirement stated in the code reflects that no specific spacing is required for both interior and exterior chimneys. This means that the chimney system associated with these types of appliances can be installed in closer proximity to neighboring structures or surfaces without the need for additional clearance, which is significantly different from the requirements for solid fuel devices, where clearances are critical to ensure safety and proper ventilation.

Understanding this requirement helps to streamline the installation process for oil or gas appliances, as installers can focus on the efficiency and functionality of the system without being encumbered by stringent spacing regulations that apply to more combustion-intensive heating methods.