What is the minimum distance a vent of a Category 4 furnace under 100,000 Btuh can terminate from a combustion air inlet?

For a Category 4 furnace with a BTU input of less than 100,000, the minimum distance for vent termination from a combustion air inlet is indeed 12 inches. This requirement ensures that combustion gases are adequately vented away from any air intake, thereby preventing the potential back-drafting of combustion products into the air supply. This margin prevents the occurrence of dangerous situations such as carbon monoxide inhalation into the building's air supply, ensuring safety and proper equipment operation.

Understanding these safety standards is crucial for maintaining a safe environment, as improper venting distances could lead to serious health risks or equipment malfunction. The specifications are aligned with the manufacturer's guidelines and the regulations in the Ontario Building Code to promote proper installation practices.