What is the purpose of auxiliary heat in a heat pump system?

The purpose of auxiliary heat in a heat pump system is indeed to provide additional heating when outdoor temperatures fall below the threshold at which the heat pump can operate efficiently. Heat pumps transfer heat from outside to inside; however, as outdoor temperatures drop, their efficiency decreases. At these lower temperatures, the heat pump may struggle to produce sufficient heat to maintain the desired indoor temperature.

Auxiliary heat serves as a backup or supplementary heating source, often in the form of electric resistance heating or a gas furnace, to ensure that the home remains warm even when the heat pump's performance diminishes due to cold weather. This additional heating helps maintain comfort levels without relying solely on the heat pump’s reduced output.

Other options do touch upon aspects related to heating and cooling systems but do not specifically address the role of auxiliary heat in relation to heat pump operation. Random increases in room temperature, controlling humidity, or enhancing cooling in summer are not part of the primary function of auxiliary heat within heat pump systems.