Regarding the operation and the controlling of the boilers, rules and regulations are subject to change due to country's applications. Nevertheless, it is clearly shown in the regulations that boilers should be operated safely without the assistance of a person when there is high-safety concern.

It can be extremely dangerous to operate boiler without water. Due to the high pressure inside of the boiler, water vapour will expand and apply forces on the boiler's walls. When the design limit is exceeded, the explosion might occur. If the water level drops to the pre-set low level, the level controller will immediately shut-off and lock the burner of the boiler. Even though, burner is fixed, it still needs to be reset manually.

To prevent such extremely dangerous events and to lock burner of the boiler safely, low level alarm limiter should be used. The limiter is used for monitoring a water minimum fill level in steam boilers. If the water level falls the below the minimum, the limiter should switch off the burner so that over heating can be prevented before injury to people or damage to installation. The level controller is self checking 52 times every second. Thus, no need for testing button for the controller.