Can natural gas appliances be common vented with oil appliances?

Natural gas appliances should not be common vented with oil appliances primarily due to differences in combustion products, venting requirements, and potential safety concerns. When natural gas and oil appliances are vented together, the products of combustion from one type of appliance can affect the operation of the other. Oil appliances produce a heavier, more sooty emission compared to natural gas, which can lead to blockages and inefficiencies in the venting system. Additionally, the venting systems are designed to handle specific types of flue gases and temperatures, and mixing fuels could cause backdrafting or improper venting, which poses safety hazards, including exposure to harmful gases like carbon monoxide. Therefore, to ensure safety and efficiency, it's essential that natural gas and oil appliances have separate venting systems.