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

In a situation where multiple vent connectors are entering a common gas vent, it is important for the venting system to function effectively and safely. The correct approach is to have the smaller connector enter at the highest level. This ensures that the venting system is designed to allow any condensation or exhaust gases to rise and exit properly. If the smaller connector is lower, it could create a situation where gases from one of the appliances could backdraft into another system or appliance, leading to potential safety hazards.

By positioning the smaller vent higher, it facilitates the proper flow of gases and prevents any interference with the drawing effect of the larger vent connectors, which are better suited to handle a greater volume of exhaust. This principle is central to ensuring that gas appliances operate efficiently and safely, adhering to the best practices of venting installations.