Abstract: A water heater includes a metallic water tank having a generally vertical orientation in use. A tube for carrying a refrigerant fluid is heat-conductively bonded about the outer surface of the wall of the tank while held under tension. The tube is formed of a material having a coefficient of thermal expansion similar to the material of the tank. The tube extends from a position below a cold water inlet at the bottom of the tank to a position approximately 66% of the height of the tank. An evaporator is positioned for exposure to ambient conditions and has a passage for carrying the refrigerant fluid. A compressor is connected to the passage and to the tube to circulate the fluid through the tube and to the evaporator.

Abstract: A vapor compression cycle refrigeration system of the type having the expansion valve (11) controlled by a temperature sensing bulb (12) at the downstream end of the evaporator (5). A by-pass line (15) is provided from the expansion valve outlet to the evaporator (5) to inject wet vapor upstream from the temperature sensing bulb (12) and provide proportioned negative feedback to the expansion valve (11) to reduce hunting or oscillating of the system.Variations of the by-pass line are also described to give positive feedback and combinations giving integral and derivative action.