what is auxiliary heat

Auxiliary heat refers to the backup heating system within a heat pump, also known as electric resistance heating. It is a secondary heating function that your thermostat automatically switches to when its too cold outside for your heat pump to extract warmth from the air. The auxiliary heat setting is designed to give your heat pump a boost when it is struggling to maintain its goal temperature. When your heat pump detects that it can't heat up to reach the ideal temperature, it automatically energizes the aux "heat strip" located inside your secondary heating source to help your system reach warmer temperatures quickly. The difference between emergency heat and auxiliary heat is that emergency heat has to be switched on manually and should only be used in temperatures of 30 degrees or below, while auxiliary heat will kick on automatically to help heat your home more quickly if there is a sudden drop in temperature.