Vacuum breakers are devices which prevent back-siphon of contaminated water to a potable water supply due to sudden vacuum conditions on the supply (inlet/feed) side. They also protect burners and heating elements inside the equipment from running dry, preventing damages and dangerous conditions. Vacuum breakers and relief valves are commonly used with water heaters (both floor standing and table-top - with bottom cold water inlet connections), unit heaters (especially with bottom and side connections), lab equipment and others.