Hot Water Heat Pumps work on a similar principal to a refrigerator; they are able to absorb energy from the surrounding outdoor air and transfer this energy into a refrigerant. The heat energy is upgraded using a refrigerant cycle and this renewable energy is transferred into the water. The R410A refrigerant used in Mitsubishi Electric Hot Water Heat Pumps has zero ozone depletion potential. This refrigerant allows useful heat energy to be absorbed even when the outdoor conditions drop below freezing.