Patent ID: 7707842

Claim:
A heat pump cycle comprising: a compressor for compressing a refrigerant; a heat exchanger downstream of said compressor; a main expansion device downstream of said heat exchanger; an evaporator downstream of said main expansion device, and a refrigerant flowing from said compressor to said heat exchanger, to said expansion device, to said evaporator, and returning to said compressor; a hot water supply to be heated in said heat exchanger, and a water pump for moving water through said heat exchanger; and a control for said cycle, said control being operable to control components and initiate a defrost mode at which refrigerant from a discharge side of said compressor is cycled into said evaporator at a relatively hot temperature to defrost said evaporator, said control being operable to stop said water pump during defrost mode, and operates to minimize the likelihood of water in said heat exchanger being unduly heated during defrost mode, said water pump being intermittently actuated during defrost made to minimize said likelihood.