Which of the following is NOT a common cause of boiler failure?

High efficiency burners are designed to improve the operational efficiency of a boiler system rather than cause failure. They operate optimally by providing precise fuel air ratios and can lead to lower emissions and reduced fuel costs. While the improper installation or maintenance of high efficiency burners can potentially contribute to issues, they are not inherently a common cause of boiler failure.

In contrast, lack of water, excessive pressure, and fluctuating temperatures are significant factors that can lead to serious boiler malfunctions. Lack of water can cause overheating and ultimately lead to boiler damage or failure due to the overheating of the boiler components. Excessive pressure can result in catastrophic failures, such as explosions or ruptures, due to the design limits of the boiler being exceeded. Lastly, fluctuating temperatures can lead to thermal stress, which might cause cracking or distortion in boiler materials. Thus, high efficiency burners represent an advancement in boiler technology that helps to mitigate these other risks rather than contributing to them.