Abstract: A pyrolytically cleaned oven includes an upper broil element and a lower bake element, the broil element is energized until the oven temperature reaches a trigger temperature, well below the glass transition temperature point of the oven porcelain enamel; then the bake and broil elements are alternately energized in a cyclical manner until an off temperature, somewhat above the trigger temperature but still below the transition temperature, is reached. Thereafter one or both of the elements are cycled to maintain the temperature with a range between the off temperature and a lower on temperature, also within the effective self cleaning range.

Abstract: A refrigerant system for a household refrigerator has its operability tested after assembly of the refrigerant system with a refrigerator cabinet. A rotary compressor of the refrigerant system is preheated, preferably by applying heat to its stator through a low AC voltage, for a predetermined period of time prior to activation of the rotary compressor. After the rotary compressor is activated, the temperature of one of the serially connected coils of the evaporator remote from the first coil is determined. If the coil temperature is within a predetermined range, this indicates the proper operability of the refrigerant system. Power consumption can be measured in conjuction with the temperature so that a significant increase or decrease in power consumption would indicate a defective refrigerant system notwithstanding the coil temperature being satisfactory.

Abstract: An excitation system for a microwave cooking appliance includes a waveguide along one wall arranged to support a standing wave therein, with an array of apertures spaced along the length of the waveguide to couple energy from the waveguide to the cooking cavity. A phase shifting device periodically shifts the phase of the standing wave between a first phase relationship and a second phase relationship. The array of radiating apertures is configured to support a first and a second substantially stationary radiating pattern when the first and second phase relationships, respectively, are established for the standing wave in the waveguide. Each radiating pattern at the cooking plane has regions of relatively high energy density interspersed wth regions of relatively low energy density, with the high energy regions of one pattern overlying low energy regions of the other, such that by periodically switching between patterns the uniformity of the time-averaged energy density at the cooking plane is enhanced.