Which condition must be met for low-water cutoff not to be required for certain boilers?

For low-water cutoff devices not to be required for certain boilers, the condition of continuous circulation must be met. Continuous circulation ensures that water is consistently flowing through the boiler, which helps maintain an adequate water level and prevents any water from dropping to dangerously low levels. This ongoing flow means that even if there is a temporary interruption in water supply, the water in the system remains at a sufficient level due to the constant movement and distribution.

In addition, maintaining continuous circulation minimizes the risk of overheating, which can occur if water levels drop unexpectedly. This condition plays a crucial role in the safe and efficient operation of the boiler, allowing for a certain level of exemption from low-water cutoff requirements as long as this continuous flow can be guaranteed.

The other conditions, while significant in their own right, do not directly replace the function or necessity of a low-water cutoff in the same way that continuous circulation does.