A unit heater is constructed similarly to which of the following?

A unit heater is constructed similarly to a duct furnace because both are designed to deliver heated air into a space for comfort heating. They typically share similar operational principles, where a heating element heats the air, and a fan circulates that air into the room.

Duct furnaces often utilize ductwork to distribute warm air throughout a building, whereas unit heaters might be more localized, often mounted on walls or ceilings to provide direct heating. The design similarities also include the use of combustion processes in some duct furnaces, akin to how some unit heaters might function, emphasizing the concurrent roles they play in heating environments.

Other options such as a boiler, which heats water for steam or hot water heating systems, and an air conditioner, which cools air, function on entirely different principles. A heat pump, while also involved in heating, typically operates by transferring heat rather than directly heating air through a dedicated furnace-like design. Therefore, the comparison focuses distinctly on the shared purpose and construction features between unit heaters and duct furnaces.