What is the primary function of a CAD cell in an oil furnace?

The primary function of a CAD cell, or Cadmium cell, in an oil furnace is to prove the presence of flame. This device operates based on light detection; when the furnace ignites, light from the flame passes through a window in the CAD cell, which detects the light and sends a signal to the furnace control system to indicate that a flame is present. This action is critical for the safe operation of the furnace, as it prevents the system from delivering fuel if there is no flame, thus avoiding potentially hazardous situations, such as fuel accumulation.

Understanding the function of the CAD cell helps highlight its essential role in the safety and efficiency of an oil furnace. It serves as a flame safeguard, ensuring that the burner only operates when there is a flame present.