What might a gurgling sound from a firing water heater indicate?

A gurgling sound from a firing water heater typically indicates the presence of mineral buildup or sediment accumulating at the bottom of the tank. This situation requires deliming or descaling. Over time, minerals like calcium and magnesium can form deposits as the water is heated. When these deposits accumulate, they can trap water beneath them, causing it to heat up and produce the gurgling sound as steam or bubbles form. This sound is not part of normal operation and suggests that the heater is not functioning efficiently. Deliming helps restore proper performance by removing these obstructions, allowing the water heater to heat water more effectively. Addressing this issue is crucial for maintaining energy efficiency and extending the life of the water heater.