What type of boiler does NOT require a gauge glass?

The correct answer indicates that both steam generators and high-temperature water heaters do not require a gauge glass. Gauge glasses are typically used in steam boilers and water boilers to provide a visual indication of the water level within the boiler. However, in the case of steam generators and high-temperature water heaters, the operational principles and design may allow for alternative methods of water level measurement or the absence of a necessity for constant visual monitoring.

Steam generators, designed to produce steam without a water storage component, generally operate under a different principle where the water is transformed into steam directly and, as such, do not maintain a water level that needs constant observation. This makes the use of a gauge glass redundant.

High-temperature water heaters function similarly, wherein the design and operational characteristics usually eliminate the need for a gauge glass. These systems often rely on pressure sensors and other types of monitoring devices that can provide the necessary safety and operational information without the requirement for a visual gauge.

In contrast, hot water boilers typically do require a gauge glass to ensure safe operation and to monitor water levels, making options that include hot water boilers inappropriate in this context. Furthermore, the combination of steam generators and high-temperature water heaters being exempt from needing gauge glasses directly supports understanding the operational differences among various boiler types