For this reason, a growing number of heat pump applications use groundwater and the earth as heating sources when adequate heat can not be supplied by an outside air source. Heat naturally flows from the higher temperature to the lower temperature. Virtually all commercially available heat pumps operate using a vapor compression cycle. In the heating mode the indoor heat exchanger receives the hot vapor, supplying heat to the indoor space. In the cooling mode the outdoor heat exchanger receives the hot vapor, therefore carrying heat from the indoor space and expelling it to the outdoors.
Heat pumps typically use reversing valves to switch from the heating to cooling mode.
Like the various heating and cooling technologies available, heat pumps when implemented correctly can be an economic solution to a facilities heating and cooling needs. Heat pumps are sized based on cooling load requirements. Application of heat pumps vary throughout the country. Often exceptionally high electrical demand rates may make natural gas cooling more attractive or the electrical utility company may have rebates or incentive programs for heat pump applications.