InterNACHI Heating, Ventilation, and Air Conditioning (HVAC) Practice Exam

A heat pump operates by transferring heat from one place to another, and its efficiency often depends on the temperature differences it can manage. When comparing a heat pump to an air conditioner, it is important to note that heat pumps are designed to work effectively in both heating and cooling modes.

In heating mode, a heat pump extracts heat from the outdoor air (even when it is cold) and transfers it indoors. This process allows the heat pump to detect a temperature difference that can be significantly greater than an air conditioner, which is primarily designed to cool indoor spaces by removing heat. An air conditioner typically works best when there is a substantial temperature difference between the indoor and outdoor environments, but it does not utilize outdoor heat for heating purposes like a heat pump does.

Consequently, when assessing the temperature difference that these two systems can detect and utilize, it is evident that the heat pump's ability to extract warmth from lower outdoor temperatures leads to a greater detected temperature difference in many scenarios, especially during colder weather. This allows heat pumps to maintain efficiency in cooler conditions compared to standard air conditioning units.