What kind of fluid does a steam boiler primarily produce?

A steam boiler primarily produces steam, which is vaporized water used for various purposes, such as heating, powering turbines, or other applications where heat energy is required. The primary function of a steam boiler is to convert water into steam through the application of heat, which then expands and can be utilized to perform work or provide energy.

While water is a component before it is heated, and there may be temporary instances of water and steam being present together (as in the case of a mixture), the main output of a properly functioning steam boiler is steam itself. This steam is what is harnessed for its energy content and is essential to the boiler's operational purpose. Thus, identifying steam as the primary product reflects the fundamental understanding of boiler operation.