Final answer:
An automatically hot water (or other liquid) boiler with over 750,000 Btu does require a low water cut off for safety reasons.
Step-by-step explanation:
In general, an automatically hot water (or other liquid) boiler with over 750,000 Btu does require a low water cut off that cuts off fuel in case of low water condition. This is because a low water condition can lead to the boiler overheating, causing damage and potentially dangerous situations. A low water cut off is a safety feature that helps prevent these situations by shutting off the fuel supply when the water level drops below a certain threshold.
For example, in large-scale industrial boilers, such as those found in power plants, a low water cut off is essential to ensure safe and efficient operation. These boilers operate at high pressure and temperature, and a low water condition can lead to a catastrophic failure.
On the other hand, smaller residential boilers and hot water heaters may have different safety mechanisms in place, such as pressure relief valves, but they may still incorporate a low water cut off as an additional safety measure.