Which of the following is a characteristic of a miniature boiler?

A miniature boiler is defined by specific characteristics, including its size and pressure specifications. The correct answer indicates that it has an inside shell diameter of 16 inches and a maximum allowable working pressure (MAWP) of 100 psi. This matches the standards used for miniature boilers, which are designed for various applications where space and pressure constraints are important.

Understanding that a miniature boiler must fit within these dimensional and pressure limits helps clarify why the other options are less appropriate. For instance, the first option mentions a minimum of 100 psi MAWP, which does not align with the definition, as miniature boilers can operate below this pressure. The second option suggests a larger inside shell diameter of 20 inches, failing to meet the size criteria for a miniature boiler. Lastly, the option stating that it can only be used in residential applications is misleading, as miniature boilers can serve a variety of applications beyond just residential use, including commercial and industrial settings. Hence, option C stands out as correctly encapsulating the essential characteristics of a miniature boiler.