Do all furnaces have a cad cell?

A cad cell, or cadmium sulfide cell, is a type of flame sensor used in many oil-burning furnaces to ensure that the burner has a flame present during operation. The primary function of a cad cell is to provide feedback to the burner control system, allowing it to shut down if a flame is not detected, thereby improving safety and preventing fuel wastage.

However, not all furnaces are equipped with a cad cell, particularly older models or those designed with different safety mechanisms. Some may rely on other forms of flame detection or safety measures that do not involve cad cells. For instance, older systems might use mechanical devices or simpler types of thermocouples.

Consequently, the assertion that not all furnaces have a cad cell is accurate. This is essential in understanding the variety of designs and technologies utilized in furnace manufacturing, as well as the range of safety protocols in place across different models and ages of equipment. Recognizing these differences is crucial for anyone involved in HVAC, as it helps in troubleshooting and maintaining various heating systems effectively.