The heat pumps that most of us are familiar with heat and cool the air inside your home. In the summer they cool the air inside your home and move the heat outdoors. In the winter they reverse the cycle and cool the outdoor air and move the heat indoors.
A heat pump is a machine or device that moves heat from one location (the ‘source’) to another location (the ‘sink’ or ‘heat sink’) using mechanical work. Most heat pump technology moves heat from a low temperature heat source to a higher temperature heat sink.1 Common examples are food refrigerators and freezers, air conditioners, and reversible-cycle heat pumps for providing thermal comfort.Heat pumps can be thought of as a heat engine which is operating in reverse. In heating, ventilation, and air conditioning (HVAC) applications, a heat pump normally refers to a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow may be reversed. Most commonly, heat pumps draw heat from the air or from the ground. Some air-source heat pumps do not work as well when temperatures fall below around −5 °C (23 °F).
The heat pump water heater is unique because moving heat from the air to the water consumes much less electrical power than heating the water directly using electric resistance elements. The energy savings typically range from 40% to 60% and in ideal applications can be much higher.
