What is the function of a vent stack in plumbing?

The function of a vent stack in plumbing is to allow air into the drainage system and prevent pressure vacuum. Vent stacks are vertical pipes that provide a pathway for air to enter the plumbing system, which is essential for maintaining proper pressure and function. Without an adequate air supply, the drainage system could develop a vacuum, leading to slow drainage or even trap siphoning, where the water seal in traps is compromised and can allow sewer gases to escape into the building.

By venting air, the vent stack ensures that wastewater can flow freely into the drainage pipes without obstruction. This balance of pressure is crucial for the effective removal of wastewater while also maintaining a safe and odor-free environment in homes. The capacity of the vent stack to perform this function helps to regulate the system's vacuum and pressure levels, which is vital for the overall performance of the plumbing system.