Access should be provided to which type of valves in plumbing?

Access should be provided to all air-admittance valves because these valves play a critical role in maintaining proper ventilation in plumbing systems. Air-admittance valves allow air to enter the drainage system to prevent vacuum formation, which can obstruct the flow of wastewater. Proper access ensures that these valves can be inspected, maintained, and replaced as needed without significant difficulty.

Regular access to air-admittance valves is essential for ensuring they function correctly, preventing issues such as sewer gas backflow or system blockages. Unlike other types of valves, which may have varying access requirements based on their function, air-admittance valves specifically require maintenance to ensure the plumbing system operates safely and effectively. Providing access promotes compliance with plumbing codes and standards, which often mandate that these valves are not enclosed where they cannot be addressed easily.