How do heat pumps work to warm up a house?

Dave - Well a heat pump basically is a pump of heat. It does matter how big the temperature difference is, but essentially it will pump heat from somewhere which is cold and somewhere which is warm. So essentially, what your fridge is doing, it's pumping heat from the cold inside your fridge to the hot outside of your fridge. It does it by compressing and expanding gases. And so basically, the way they're rigging these heat pumps is essentially they're taking the inside of your fridge and putting it outside so that taking heat from outside and putting the hot pipes at the back of your fridge, where the heat gets pumped to, inside your house so it keeps it nice and warm. The bigger the temperature difference is though, the more electricity you need. Ben - So, when you're dealing with a whole house scale, can that really work? Obviously, a fridge is quite small, it's well insulated, it's very contained. Can you really heat a house using that technique? Dave - You certainly can people do and you can shift sort of between three and five times as much heat as electricity would've produced, just by running an electric heater inside. Ben - I certainly noticed when we bought a freezer and installed it in our garage that our garage seemed to be a lot warmer than it used to be. Same sort of thing going on? Dave - Yeah. Basically, it's pumping heat from inside the freezer to outside and it's not very efficient, so you need sort of extra electricity in there, so that electricity goes heating up your house.