Q: My new home has a thermostat setting for “Emergency Heat?” When is the appropriate time to use that setting?
A: “Emergency Heat” is an optional setting for a heat pump, but it should only be used in true emergency situations, such as when your heat pump has stopped working altogether. Heat pumps condition the air of your home by moving or “pumping” heat out of the house in the summer and into the house in the winter. During colder months, it becomes difficult for the pump to extract heat from the outside air, so heat pumps require a secondary heating source, which is usually located in the indoor unit. As temperatures fall, your heat pump (first-stage heat) automatically taps into the Emergency Heat source (second-stage heat) in order to heat your home. Most heat pumps use electric heat coils (like a toaster) as a backup, but those electric coils use a lot of electricity. And when you run a heat pump on “Emergency Heat,” you’re using those heat coils constantly. The heat pump will stop trying to extract heat from outside and instead it will use only the backup heat to warm your home. Operating the system this way essentially turns your heat pump into an electric furnace—which costs even more to run than a gas furnace and defeats the purpose of having an efficient heat pump. So, only use the “Emergency” setting when the heat pump has stopped working completely, and if that’s the case then you should call an HVAC professional.