What is the recommended slope for PVC venting pipe toward the furnace per linear foot?

The recommended slope for PVC venting pipe toward the furnace is 1/4-inch per linear foot. This slope is necessary to ensure proper drainage of condensation that can form within the venting system. If the slope is insufficient, it can lead to water pooling in the vent, which may cause blockages and result in the vent system not functioning properly. This can, in turn, create a dangerous situation where exhaust gases are not able to escape efficiently, potentially leading to backdrafting or other safety hazards. A 1/4-inch slope strikes a balance between effective drainage and structural feasibility within typical piping installations, making it the most widely recommended standard for residential venting systems.