Instantaneous hot water heat pump

An instantaneous hot water appliance, comprising:

• a heat pump, the heat pump constructed for connection to source water;
• a heat exchanger, the heat exchanger constructed for connection to a domestic hot water system of a facility;
• and a water pump, wherein the heat pump extracts heat from the source water and cools the source water, and wherein the heat pump and the heat exchanger are connected within a closed loop utility water system, and utility water in the closed loop system is heated by the heat pump and circulated by the water pump to the heat exchanger, wherein heat is exchanged within the heat exchanger from the utility water in the closed loop system, and the water pump circulates the utility water within the closed loop water system from the heat exchanger to the heat pump, where the utility water is again heated, and further comprising a condenser outlet temperature sensor that is constructed to communicate with utility water exiting the condenser, and a controller, wherein the controller actuates a first compressor of the heat pump when the utility water exiting the condenser decreases to the first temperature and terminates actuation of the first compressor of the heat pump when the utility water exiting the condenser reaches a second temperature that is higher than the first temperature, and the controller actuates a second compressor of the heat pump when the utility water exiting the condenser decreases to the third temperature and terminates actuation of the second compressor of the heat pump when the utility water exiting the condenser reaches a fourth temperature.