When two or more vent connectors enter a common vent, which connector should enter at the highest level?

In a situation where two or more vent connectors enter a common vent, the smallest connector should enter at the highest level. This practice is important for ensuring effective venting and proper airflow within the system. The rationale behind this is that smaller diameter pipes create a higher velocity of exhaust gases, allowing them to rise more effectively. This helps prevent any potential backdraft, ensuring that exhaust gases are properly expelled and do not re-enter the appliance.

Additionally, positioning the smaller connector at a higher level takes advantage of the natural tendency of hot gases to rise, enhancing the efficiency of the venting system. When larger or equal size connectors are used at the higher level, it could result in poor draft and potential accumulation of gases, leading to safety hazards such as carbon monoxide build-up.

By following this guideline, the safety and efficiency of the venting system are maintained, significantly reducing the risk of vent obstruction and ensuring that all appliances function correctly.