Air-To-Air Heat Pump
This is an air conditioner that works in reverse. It provides both cooling and heating to your home from the same piece of equipment (if you’ve ever seen an a/c running in the winter, that was a heat pump).
In heat mode, it extracts hot air from the cold air outside to heat your home.
It’s efficient down to about 35° F. Lower than that and it starts to cost more than $1 to get $1 worth of heat.
As the temperature continues to drop, the thermostat will automatically switch to the furnace for heat.
Lifespan: 20-25 years