A vent with a developed length of 53 ft. serving a 3-inch drain line should be what size?

In plumbing, the size of vents is critical for ensuring proper air flow and preventing negative pressure in the drainage system. For a 3-inch drain line, the plumbing code typically specifies that the vent size should be either equal to or larger than the drain size to adequately support the drainage function.

In this case, the developed length of the vent is 53 feet, which is a substantial length. Vents must be able to effectively handle air pressure fluctuations and provide sufficient venting for the drain system over long distances. A vent that is the same size as the drain (in this case, 3 inches) is often recommended for optimal performance. This allows for a balanced system where air can enter to replace the water moving through the drain line, preventing any potential issues like siphoning or trap sealing.

Thus, for a 3-inch drain line, a vent size of 3 inches is appropriate and follows the guidelines for maintaining effective drainage performance, especially over longer vent lengths such as 53 feet.