PURPOSE: To achieve operations of cooling, refrigerating and freezing using a heat pump into which an alternative refrigerant gas HFC(fluorocarbon containing hydrogen) is injected singly or in a mixture.

CONSTITUTION: An air-cooled condenser 2A is provided with an air-cooled condenser 2B additionally and the condensing temperature of a refrigerant is set to a low temperature within the atmospheric temperature plus 5°C to perform an operation. A water-cooled condenser 2C1 is provided with a water- cooled condenser 2C2 additionally and the condensing temperature of the refrigerant gas is set to a low temperature, by 1°C or higher than the temperature of cooling water being sent to the water-cooled condenser.