A pressure vacuum breaker, or PVB, is a backflow prevention device designed to keep contaminated water from entering your clean water supply. It works by using a spring-loaded check valve and an air inlet valve that open and close based on pressure changes in your system. When pressure drops unexpectedly, the vacuum breaker allows air into the line to prevent dirty water from reversing flow. Radiant Plumbing & Air Conditioning installs and services these devices to help protect plumbing systems that require secure backflow prevention.