Vertical drainage lines connecting with horizontal drainage lines should enter through what type of fitting?

The correct fitting for vertical drainage lines connecting to horizontal drainage lines is a 45 Degree Wye. This fitting is specifically designed to facilitate smooth transitions between pipes at an angle. When a vertical line intersects with a horizontal line at a 45-degree angle, it promotes better flow and minimizes the risk of clogs or obstructions.

Using a 45-degree angle reduces turbulence compared to a sharp 90-degree angle, allowing waste to flow more freely. Proper flow dynamics are crucial in plumbing systems, as they help ensure the efficient movement of water and waste through the pipes.

Other options, such as a 90 Degree Elbow or Standard Straight Pipe, do not provide the same benefits for the transition between vertical and horizontal runs. A combination tee also varies in function and is typically used for more complex connections rather than the straightforward transition specified in this scenario. Thus, the use of a 45 Degree Wye fitting is recommended in order to maintain efficient drainage in plumbing systems.