What does an air admittance valve do in a plumbing system?

An air admittance valve is designed to allow air into the drainage system. This is crucial for maintaining proper pressure within the system, especially in situations where vents are not readily available. By allowing air to enter, the valve prevents the formation of a vacuum that could hinder wastewater flow. This function is particularly important in maintaining the pressure balance within the drainage system, which supports efficient drainage and prevents issues like slow drainage or gurgling sounds.

The need for air to be admitted into the drainage system is vital, as it helps to facilitate smooth flow and prevent any blockages that could occur if the system were sealed. This valve operates automatically, opening to let air in when the pressure in the drainage system drops and closing when the pressure is normalized. This functionality is essential in residential and commercial plumbing to ensure that the drainage system works effectively without the need for traditional venting.