What action should be taken if a cad cell becomes covered with soot?

When a cad cell, or cadmium sulfide photoresistor, becomes covered with soot, it can lead to malfunctioning of the oil burner. Cleaning the cad cell is essential because soot accumulation inhibits its ability to detect the presence of flame, which is crucial for the safe operation of the burner.

By cleaning the cad cell, you ensure that it can effectively fulfill its role of detecting light levels emitted from the flame, which helps in adjusting the fuel supply. If the cad cell remains dirty, it can lead to incomplete combustion, wasted fuel, and potentially hazardous situations, such as the risk of fire or explosion.

Additionally, it is important to investigate the underlying cause of the soot buildup. This might include checking the burner settings, oil quality, or the overall combustion efficiency. Addressing the root cause not only aids in maintaining the functionality of the cad cell but also enhances the overall efficiency and safety of the heating system.

Thus, cleaning the cad cell and investigating the cause is the appropriate action to ensure the system's safety and efficiency.