Heat pumps are also more efficient if you leave the thermostat alone, or adjust it in small increments. With the one we have (and they can be different) the "emergency" heat comes on any time the thermostat differential is 2F. Emergency means the whole system is a giant space heater, which uses twice as much (or so) electric. I have no idea how much electric we save using the stove. This year we have used the heatpump only two or three times. I like the heat from the stove. It feels warm. The heatpump never really made anything feel warm.