The Heat Pump is a piece of equipment that utilizes a refrigeration cycle to cool or heat up a space.
COOLING MODE:
HEATING MODE:
Note: Not all Heat Pumps use air to reject the heat! Some use water and some sort of heat rejection equipment (condensing unit/cooling tower/fluid cooler...etc)
When a Heat Pump goes into "Heating" mode - it often can not keep up with the loads, thus most Heat Pumps have some sort of suppliment heating (strip resistive heater, geothermal or even boilers.
Have you ever seen a Heat Pump?
Below is a 2.5 Ton - Heat Pump (Air Source)
Here is another 4.0 Ton - Heat Pump (Air Source)
While it may be slightly bigger, the mechanics are exactly the same.