EMERGENCY HEAT / AUX. HEAT
The balance point (when it can no longer efficiently transfer heat from the outside air) of an air source heat pump, is usually about 35 degrees. The thermostat senses this and automatically turns on the electric heat strips to provide the additional heat needed. It signals this by turning on the “AUX” heat light. Emergency heat is the back up electric heat built into a heat pump system. The same as an auxiliary heater, except it is used exclusively as the heat source when the heat pump needs repair.