Why might auxiliary heat be required for certain heat pump systems?

Auxiliary heat may be required for certain heat pump systems because, in some situations, the heat pump alone cannot produce enough heat to meet the heating demands of the space. This can occur particularly during extremely cold outdoor temperatures when the heat pump's efficiency decreases, and its ability to extract heat from the outside air is significantly diminished.

In these scenarios, the heat pump may rely on auxiliary heating sources—such as electric resistance heaters or gas furnaces—to supplement the heating output and ensure that indoor temperatures remain comfortable. This supplemental heat allows the system to maintain adequate heating levels during peak demand periods or adverse weather conditions, making it essential for systems designed to operate in colder climates where temperatures frequently drop below the heat pump's effective range.