A heat pump with a COP of 3.0 is used to heat air contained in a 1205.4m^3 of well-insulated, rigid tank. Initially the pressure and the temperature inside the gas tank are 100 kPa and 7 degrees Celsius, respectively. When running, the heat pump consumes 5kW of electric power. How long does it take for the heat pump to raise the temperature of air in the tank to 22 degrees Celsius?