Winter / Heating
In heating mode the outdoor units heat exchanger is used to absorb heat energy from the surrounding outdoor air using refrigerant as the heat transfer medium.
The hot refrigerant is pumped through copper pipes to the indoor units heat exchanger and the heat energy is transferred to the cooler indoor room air as the air passes over the indoor heat exchanger warming the room.
Summer / Cooling
In cooling mode the indoor units heat exchanger is used to absorb heat energy from the indoor room air using refrigerant as the heat transfer medium cooling the room air.
The refrigerant is then sucked back to the outdoor unit through copper pipes and the heat energy is rejected into the surrounding air outside via the outdoor units heat exchanger.
There are two key parts to a heat pump system
There is an outside unit housing the compressor that is similar to the exterior back of your fridge. It draws heat energy from the outside air in even the coldest of weather. That heat energy is then transferred inside the home using a refrigerant process through a piping system powered by an indoor fan unit that is typically mounted to the wall. In summer, the reverse happens – heat energy is drawn from the interior room and expelled by the outside unit. While the system is often referred to as a heat pump rather than air conditioning – both are in fact the same.