How does a heat pump provide both heating and cooling capabilities?

A heat pump provides both heating and cooling capabilities primarily by using a switch to change the direction of refrigerant flow. This is accomplished through a component called a reversing valve. In cooling mode, the heat pump extracts heat from the indoor air and transfers it outside, while in heating mode, it does the opposite—extracting heat from the outdoor air and transferring it indoors. This dual-functionality is what distinguishes heat pumps from traditional heating or cooling systems, allowing them to efficiently operate year-round in varying temperatures.

The other options present limitations or restrictions that are not applicable to how heat pumps function. For example, the idea that a heat pump can only be installed in homes with duct systems is inaccurate, as there are ductless systems that operate just as effectively. Similarly, requiring an additional heating unit suggests that the heat pump is not capable of providing sufficient heat on its own, which contradicts the design and efficiency of modern heat pumps. Lastly, operating solely in heating mode ignores the versatility of heat pumps, which are designed to switch between heating and cooling based on seasonal needs.