Furnace volume in a boiler is measured in which unit?

The volume of the furnace in a boiler is measured in cubic feet because volume refers to the amount of space that an object occupies in three dimensions. To express this, the unit must indicate three-dimensional space, which is precisely what cubic feet does. It encompasses length, width, and height, providing a true measurement of the volume where combustion takes place in a boiler.

Other options do not adequately represent volume in three dimensions. Square feet and square meters measure area, which only accounts for two dimensions (length and width), while liters, though a valid volume measurement, are typically used in contexts involving smaller quantities of fluid rather than large volumes typical of industrial boilers. Therefore, cubic feet is the most appropriate unit for measuring furnace volume.