Infographic: How Heat Pumps Work

One of the most hard-to-replace applications for fossil fuels is space heating. When you burn fuel, most of the released energy is in the form of heat, which can be applied directly to heating the air. One alternative is resistive heating, which uses electricity to warm up coils. The cost of electricity per Btu is generally several times higher than gas, which makes resistive heating more expensive even if all the electricity is converted to heat.

Heat pumps improve on standard electric heating. Rather than use electricity directly, heat pumps take advantage of the thermodynamic properties of a refrigerant to move heat from one place to another. By some estimates, the amount of heat a heat pump can bring to a space can be as much as twice the energy content of the electricity needed to run the device.

That sounds like magic, but heat pumps involve standard engineering. Here’s how they work.