A heat exchanger element and a water heater using same

摘要

Disclosed herein is a heat exchanger element 22 for carrying a refrigerant fluid, the heat exchanger element comprising an inner tube 22a and an outer tube 22b both formed from heat conductive material. Substantially the entire inner surface of the outer 5 tube 22b is in contact with the outer surface of the inner tube 22a. A transverse cross section of at least a portion of the inner and outer tubes has a non-circular shape and/or the inner tube may be formed from copper and the outer tube from stainless steel. Also disclosed is a heat pump water heater 10 comprising a bypass circuit having a first end 28 connected to the heat pump circuit between the compressor 20 and the condenser 22 10 and a second end 30 connected to the heat pump circuit between the expansion device 24 and the evaporator 18. The bypass circuit includes a valve 32 for selectively diverting a portion of relatively hot refrigerant output from the compressor 20 to the evaporator 18. 6g24 Fig. 1