Chapter 19.2, Problem 2R

A major hazard involved with water heaters is that they operate under whatever pressure the serving water utility supplies. Water stays liquid at temperatures higher than the normal boiling point of 212°F (100°C). If the high-temperature limit control failed to operate for whatever reason, should a pipe burst or a faucet be opened, the pressure would instantly drop to normal atmospheric pressure, causing the superheated water to turn into ______________ that could result in ______________. To prevent this from happening, water heaters are equipped with pressure/temperature relief valves.