ELI5: Explain Like I'm 5

heat pump

A heat pump is like an air conditioner that can do two different jobs. It can both cool your home in the summer like an air conditioner and heat your home in the winter like a furnace. It does this by transferring warmth from one place to another. In the summer, the heat pump moves heat from inside your house to outside and in the winter, it moves heat from outside to inside. It does this by using a special kind of gas called a refrigerant. The refrigerant changes from a gas to a liquid and back again, transferring warmth along the way.