What device is used to detect flames in a burner chamber?

The device used to detect flames in a burner chamber is the cad cell. A cad cell, or cadmium sulfide cell, is a type of photoelectric sensor that is sensitive to light. When a flame is present, it emits light, and the cad cell detects this light. This detection is crucial for ensuring that the burner is operating safely and efficiently. If the flame goes out for any reason, the cad cell will not detect the light, and this will trigger a safety mechanism to shut off the fuel supply to prevent dangerous conditions, such as an explosion or accumulation of unburned fuel.

The other devices listed serve different purposes in heating systems. For instance, a thermostat regulates temperature but does not detect flames. A pressure gauge monitors the pressure within a system, such as a gas line or boiler, but does not have the capability to sense flame presence. A flame thrower is entirely unrelated, as it is a device designed to project a flame rather than detect one.