Which option is NOT an advantage of a packaged firetube boiler?

The option stating that a packaged firetube boiler is large enough for large-scale power generation is not an advantage. Packaged firetube boilers are typically designed for smaller applications and moderate heating demands, making them unsuitable for large-scale power generation, which often requires larger, more complex boiler systems capable of handling significantly higher capacities.

In contrast, the first three options highlight notable advantages of packaged firetube boilers. They are factory-tested before delivery, which helps ensure that they operate as intended upon installation. This thorough testing contributes to greater reliability and fewer issues at startup. Quality assurance measures also ensure that the boilers meet specific standards, minimizing defects and enhancing overall performance. Furthermore, the mass production of these boilers leads to a lower purchase price, making them an economical choice for many commercial and industrial applications. Thus, the chosen answer accurately reflects a limitation of packaged firetube boilers compared to their advantages.