What is the primary difference between a steam boiler and a hot water boiler?

The primary difference between a steam boiler and a hot water boiler is indeed that a steam boiler produces steam. Steam boilers operate by heating water to a temperature at which it converts to steam. This steam can then be utilized for various applications, including heating spaces, driving turbines for power generation, or providing heat for industrial processes.

When considering the other choices, a hot water boiler typically operates at lower temperatures and provides heated water for direct use in heating applications, such as hydronic heating systems. While energy efficiency can vary depending on design and application, the standard distinction remains centered on their function of producing steam versus hot water. The claim that a steam boiler is used exclusively for heating water or that hot water boilers are for power generation does not align with the primary operational characteristics of these systems. Steam boilers are specifically designed to convert water into steam for those various applications.