What could be a consequence of a dirty cad cell in an HVAC system?

A dirty cad cell can lead to several operational issues within an HVAC system, one of which is that it can prevent the burner from starting altogether. The cad cell, or cadmium sulfide cell, is a safety component that detects the presence of a flame. When it is clear and functioning properly, it allows the burner to operate. However, if the cell is dirty or obscured, it may not accurately detect the flame, resulting in the burner not receiving the signal to start. This occurs because the sensor fails to sense the light emitted by the flame or misreads the intensity due to the buildup of dirt, soot, or other debris.

In the context of the other answers, improved fuel efficiency would not be a consequence of a dirty cad cell, as proper operation relies on a clean environment for the cell to function accurately. Unstable flame quality is also a result of flame detection issues but does not directly lead to the burner failing to start. Continuously running burners would suggest a malfunction in the safety mechanisms that the cad cell provides, which is also not a direct consequence of dirt obstructing the cell. Therefore, the most direct and likely scenario resulting from a dirty cad cell is that the burner simply will not start, focusing on the critical role