Which electrical device alerts when water levels are low in a boiler?

The correct answer is the low water alarm. This device is specifically designed to monitor the water level in a boiler. It serves an essential safety function by issuing an alert when the water level drops below a predetermined threshold. Maintaining adequate water levels in a boiler is crucial because low water conditions can lead to overheating, equipment damage, or even catastrophic failure. The low water alarm acts as a critical safeguard, ensuring that operators are immediately notified of any potentially hazardous situation.

In contrast, a flow switch detects the movement of water or other fluids in a system, ensuring that there is adequate flow, but it does not measure water levels. The damper motor controls the airflow in the boiler's combustion system, influencing the efficiency of combustion but not directly related to water levels. The ignition transformer is involved in igniting the fuel in the combustion chamber and does not monitor water levels. Thus, the low water alarm's dedicated function to monitor and alert users about low water conditions in a boiler makes it the correct choice in this context.