Which type of boiler is characterized by its use of water cooling?

The wetback boiler is characterized by its design, which includes a water-cooling feature in the back of the boiler. This type of boiler has water jackets surrounding the combustion chamber, resulting in improved heat transfer efficiency and safer operation. The water surrounding the combustion area absorbs heat, which not only aids in reducing temperatures within the boiler but also provides additional thermal efficiency by using the heat that would otherwise escape into the atmosphere.

In contrast, firetube boilers primarily utilize heated gases that pass through tubes submerged in water, whereas condensing boilers maximize heat recovery from flue gases without the specific design features seen in wetback boilers. Steam boilers can refer to various types that generate steam, but they do not necessarily incorporate the specific water-cooling feature that defines wetback boilers.