What is the function of air admittance valves (AAVs)?

Air admittance valves (AAVs) serve a critical role in plumbing systems by allowing air to enter the drainage system while simultaneously preventing the escape of sewer gases. This function is essential to maintain proper air pressure and facilitate drainage without the need for traditional venting methods that extend through the roof. By permitting air to equalize pressure changes that occur during drainage, AAVs help prevent siphoning of trap seals, thus preventing foul odors from gases in the sewer system from entering the building.

Understanding the necessary balance between air and liquid in plumbing is vital for maintaining effective drainage and sanitation. AAVs achieve this balance, making them particularly useful in situations where extending a vent line is impractical or where space is constrained. Their design allows them to open and close automatically based on pressure changes within the system, ensuring a smart response that contributes to the overall efficiency and functionality of the plumbing network.