Which issue can be caused by a faulty cad cell?

The cad cell, or cadmium sulfide photoresistor, plays a crucial role in the operation of an oil burner by detecting the presence of a flame. If the cad cell is faulty, it may fail to accurately sense the flame's presence, leading to the control system thinking there is no flame at all. As a result, the burner will not ignite, causing a failure to start the heating process.

When the cad cell fails, it does not provide the necessary feedback to the burner control that ensures safe and proper operation. Consequently, the absence of ignition can lead to various operational inefficiencies and discomfort in spaces that rely on the heating system. Proper functioning of the cad cell is critical for the ignition sequence, making its failure a significant concern in HVAC operations.