Heat pump and method for operating heat pump

A heat pump, comprising:

• a compressor that compresses a refrigerant;
• at least one fluid-refrigerant heat exchanger that exchanges heat between the refrigerant and a fluid;
• a pump including a motor, the pump forcing the fluid to flow into the at least one fluid-refrigerant heat exchanger;
• and
• a controller configured to:
• calculate power consumption of the pump;
• calculate a flow rate of the fluid flowing due to the pump based on the calculated power consumption;
• calculate an average and a standard deviation of the power consumption calculated for a predetermined period of time;
• determine a ratio of fluid that is a liquid to air flowing through a pipe connected to the pump based on the average and the standard deviation of the power consumption;
• and
• control an operation of the pump to be stopped based on at least one of a case where the flow rate of the fluid is less than a predetermined reference flow rate or a case where the determined ratio is equal to or greater than a predetermined ratio.