Which measurement is associated with the term 'heating boiler'?

The term 'heating boiler' is associated with boilers that operate at lower pressure levels compared to other types of boilers, such as high-pressure steam systems. Specifically, a heating boiler is classified as one that operates below a pressure of 103 kPa (or 15 psi). This classification is important as it signifies a distinct set of operational guidelines, safety standards, and regulatory compliance tailored to low-pressure systems.

Heating boilers are primarily used for space heating and hot water applications in residential and commercial settings. By maintaining operation below 103 kPa, they are generally safer and have simpler controls compared to higher pressure systems, which can involve greater risks and require more stringent controls.

The other pressure levels mentioned do not accurately classify a heating boiler, highlighting why measuring pressure levels above, exactly at, or just at the threshold of 103 kPa are not aligned with the standard definition of a heating boiler. Therefore, recognizing that a heating boiler operates specifically below this pressure threshold is essential for understanding its classification and usage in the power engineering field.