Abstract: In an air conditioning system with a variable speed compressor drive, the discharge temperature is sensed and if it is found to exceed a predetermined threshold limit for a predetermined period of time, then the compressor speed is reduced by an incremental amount. If this condition persists, the compressor speed will continue to be reduced in incremental steps until the temperature of the discharge gas is reduced to a level below the predetermined threshold limit.

Abstract: An integrated heat pump and hot water system of the type having a variable speed compressor is controlled during a water heating mode, in which outdoor air serves as the heat source. The controlling is carried out on the basis of a field of outside temperature and water temperature. The compressor speed is controlled based on the outdoor air temperature, and the compressor is run at a maximum speed between a minimum outdoor temperature and a low temperature somewhat above the minimum, at minimum speed for outdoor air temperature between a maximum temperature and a high temperature below the maximum temperature, and at a speed that depends linearly on outdoor temperature for intermediate outdoor temperatures. There is a permissible temperature field or envelope bounded by the minimum and maximum outdoor temperatures, by minimum and maximum water temperatures, and by an efficiency floor and a torque limit ceiling.

Abstract: An integrated air conditioning and water heating system provides cooling of a comfort zone, as required, as well as water heating. A variable speed compressor delivers compressed refrigerant first to a water heat exchanger and then to an outdoor condenser coil. From there the refrigerant cycles through an indoor evaporator coil back to the compressor. When the demand for water heating is above a predetermined amount and the cooling load is below a predetermined cooling load threshold, a full condensing mode is selected in which most of the heat from the comfort zone is used for water heating. If the cooling demand is high or if the water heating demand is low, a desuperheating mode is selected in which most of the heat is transferred to the outdoor air. The outdoor coil temperature is monitored and if it is above a safe limit, the desuperheating mode is selected. In the full condensing mode the outdoor fan is held off. In the desuperheating mode, the outdoor fan is energized.

Abstract: Temperatures in the inside heat exchanger or both the inside and outside heat exchangers of a reversible vapor compression refrigeration system are sensed before and after a system startup or mode change. If the reversing valve is positioned properly, the temperature should change in a certain way because of the operating change, e.g., on a startup in cooling mode, the inside heat exchanger temperature should decrease. If the temperatures actually sensed do not change in the predicted way, it is an indication that the reversing valve is incorrectly positioned for the operating mode selected. If the temperature changes indicate that the reversing valve is out of position, the variable speed compressor is operated at its maximum speed for a short time. If the temperature change is now as expected, the valve has changed to the proper position. If the temperatures still have not changed in the way predicted, the reversing valve is still improperly positioned.

Abstract: A method of controlling compressor current in an air conditioning system having a variable speed compressor which has a predetermined current limit. The actual compressor speed is sensed and compared to a requested predetermined compressor speed. Corrective steps are taken to reduce compressor load if the sensed compressor speed falls below a requested predetermined compressor speed.

Abstract: The temperature is sensed at the compressor, indoor coil and outdoors. The sensed temperatures are compared and if the compressor temperature is not a specified amount higher than the lower of the other two sensed temperatures, then the crankcase heater is energized. When the compressor temperature rises to or is a specified amount above the lower of the other two temperatures, the crankcase heater is deenergized.

Abstract: An integrated heat pump and hot water system including a water to refrigerant heat exchanger having a refrigerant evaporating circuit and a refrigerant condensing circuit that are in heat transfer relation with the water circuit. A bi-flow expansion valve with a positive shut off feature is mounted in the refrigerant liquid line connecting the indoor and outdoor coil of the heat pump. The refrigerant evaporator circuit is connected between the inlet of the compressor and the liquid line by an evaporator line that enters the liquid line between the bi-flow expansion valve and the outdoor coil. A solenoid actuated metering valve is placed in the evaporator line to control the flow of refrigerant passing through the evaporator circuit. The condensing circuit of the heat exchanger is connected directly to the discharge line of the compressor so that the refrigerant discharged from the compressor passes through the condensing circuit.