"A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure (1\u2013300 psi or 6.895\u20132,068.427 kPa) but, at pressures above this, it is more usual to speak of a steam generator.A boiler or steam generator is used wherever a source of steam is required."@en . . .