Which device triggers a safety shut-down requiring a manual reset?

The auxiliary low-water cut-off is a critical safety device used in steam boilers and other water systems to prevent low-water conditions that can lead to overheating and damage. When the water level in the boiler drops below a certain threshold, the auxiliary low-water cut-off detects this situation and triggers a safety shut-down of the system. This action is necessary to protect the equipment and ensure safety.

In this case, after the device has activated the shut-down due to low water levels, a manual reset is required before the system can be restarted. This ensures that the operator checks the water level and addresses any issues before resuming operation, thereby enhancing safety.

Other devices mentioned, such as high-pressure cut-offs and pressure relief valves, typically function automatically and do not require manual resetting upon activation. Thermostats work on a different principle related to temperature control, and while they may initiate a shut-down, they do not necessitate a manual reset in the same way that an auxiliary low-water cut-off does.