What happens to the burner during a low fire state?

In a low fire state, the burner is set to operate at minimal capacity, which is why the correct answer indicates it's at minimal operation. This setting is typically used to maintain safe and efficient boiler operation during periods of lower demand for steam or hot water. By reducing the firing rate, the system can conserve fuel while still producing enough heat to meet the current load requirements. This helps maintain stability within the system and reduces wear and tear on the components, as it prevents the burner from cycling on and off excessively, which can be inefficient and damaging over time.

In contrast, operating fully would indicate maximum capacity, which is not the case in low fire. Being shut down means the burner is not active, and standby mode typically refers to a state where the burner is prepared to ignite but not actively firing. Thus, minimal operation accurately describes the function of the burner in this particular state.