Which automatic boiler component must be adjusted prior to conducting a boiler soot blow?

The correct answer is the fuel air ratio relay. This component is crucial for maintaining the appropriate balance between fuel and air supplied to the boiler during operation. Prior to conducting a soot blow, it's essential to ensure that this ratio is correctly adjusted to prevent incomplete combustion, which can lead to increased emissions and operational inefficiencies.

A soot blow, which involves the removal of accumulated soot and ash from the boiler tubes, requires the boiler to operate under optimal conditions to ensure effective cleaning without causing damage or inefficiency. If the fuel air ratio is not properly set, the combustion process may be disrupted, leading to potential issues such as unstable flame characteristics or excessive soot buildup.

Adjusting the fuel air ratio relay before a soot blow not only optimizes boiler performance but also supports safety measures, ensuring that any adjustments made do not compromise the operation of the boiler during the soot blowing process.