What’s the difference between heat and auxiliary or emergency heat on my heat pump thermostat?
Your heat pump system has two ways of heating your home. The first way uses refrigerant circulated between the outdoor unit (heat pump) and indoor unit (air handler). The heat produced is sufficient when outdoor temps are above 35 degrees. When it’s colder outside, your system uses electric heating strips (similar to those in a portable heater) to supplement the heat produced by the refrigerant method. Your thermostat automatically senses when this extra heat is needed, and turns it on. When this happens the thermostat will display an “AUX. HEAT” (auxiliary heat) light or lettering. It’s normal to occasionally see the auxiliary heat on during normal operation or when temps are low outside. If your heat pump is broken, you can manually turn on the electric heat strips by setting your thermostat to “EM HEAT” (emergency heat). This will turn off the first method of heating and use more electricity so should not be used for extended periods.