A refrigerator appliance may be provided that includes a housing, a first fluid-motivating unit (FMU), a second FMU, and a controller. The housing may define a chilled chamber. The first FMU may be mounted to the housing. The second FMU may be mounted to the housing apart from the first FMU. The controller may be in operable communication with the first FMU and the second FMU. The controller may be configured to initiate a cooling operation. The cooling operation may include activating the first FMU to generate a first fluid flow, increasing a speed setting of the first FMU gradually at a first predetermined ramp rate, activating the second FMU subsequent to activating the first FMU to generate a second fluid flow, and increasing a speed setting of the second FMU gradually.

A refrigeration appliance includes a freezer compartment fluidly coupled to an ice maker compartment via an ice maker return duct. An internal sensor is positioned within the freezer compartment and configured to sense a first condition within the freezer compartment. An external sensor is coupled to said refrigeration appliance and configured to sense a second condition external to said refrigeration appliance. A return fan is positioned within the ice maker return duct. A controller is operably coupled to the internal and external sensors to receive sensed first and second conditions. The controller is configured to determine a differential between the sensed first condition within the freezer compartment and the sensed second condition external to said refrigeration appliance. The controller activates the return fan to blow air from the ice maker compartment into the freezer compartment in response to the differential.

A control method of a refrigerator includes: determining whether a first temperature of a refrigerating compartment satisfies a first temperature condition; based the first temperature satisfying the first temperature condition, determining whether a second temperature of a freezing compartment satisfies a second temperature condition; based on the second temperature satisfying the second temperature condition, determining (i) whether a third temperature of an ice making compartment satisfies a third temperature condition and (ii) whether a driving time for ice making has passed; maintaining operation of a compressor while determining (i) whether the second temperature satisfies the second temperature condition, (ii) whether the third temperature satisfies the third temperature condition, and (iii) whether the driving time has passed; and stopping operation of the compressor based on at least one of (i) a determination that the third temperature satisfies the third temperature condition or (ii) a determination that the driving time has passed.

A control method for controlling a refrigerator includes a first step for driving a compressor for compressing a refrigerant and a fan for moving air, a second step for driving the compressor and stopping the fan, a third step for stopping the compressor and driving the fan, and a fourth step for stopping the compressor and the fan.

A heat pump water heater has a tank, a heat source, and a heat pump system. The heat pump system has a refrigerant path, at least a portion of which is in thermal communication with the water tank volume so that heat transfers from refrigerant to the water tank volume. A fan causes air to flow through a housing, and another portion of the refrigerant path includes an evaporator in the housing. The fan is within the housing and may further be within a second housing. The first housing may comprise a baffle to direct air flow. The fan may be a variable speed fan in communication with a controller, so that the controller controls the fan speed depending on a temperature of the refrigerant.

An HVAC system includes a controller communicatively coupled to a subcool sensor, an outdoor temperature sensor, a compressor, and a blower of the HVAC system. For a first period of time, the controller periodically determines subcool values. For each determined subcool value, a corresponding compressor speed, outdoor temperature, and blower speed are determined. A baseline database is generated with baseline values associated with normal operation of the HVAC system. Following the first period of time, subcool values are determined based on the subcool signal. For each subcool value, a corresponding compressor speed, outdoor temperature, and blower speed are determined. The controller determines whether each subcool value satisfies a criteria based on the baseline database. If the criteria are not satisfied for at least a threshold time, the system is determined to be operating under a fault condition, and a corresponding alert is transmitted.

A fan drive circuit for a variable speed fan motor in a cooling system, includes an inverter configured to supply a current signal to stator windings of the variable speed fan motor, a frequency detection circuit coupled to an output stage of an inverter of a compressor motor of the cooling system and configured to detect a first frequency of a compressor current signal at the output stage of a variable speed compressor drive circuit and generate a frequency signal, and a digital signal processor (DSP) coupled to the inverter and the frequency detection circuit. The DSP is configured to receive the frequency signal corresponding to the first frequency from the frequency detection circuit, select a second frequency corresponding to the first frequency at which to operate the variable speed fan motor, and transmit control signals to the inverter to supply current to the stator windings at the second frequency.

A method of controlling a refrigerator includes starting a first cooling cycle to cool a first storage compartment by operating a compressor and a first fan, determining whether a start condition of a second cooling cycle to cool a second storage compartment is satisfied, operating a second fan for the second storage compartment when the start condition of the second cooling cycle is satisfied, determining whether an output change condition of the second fan is satisfied while the second fan operates, and changing a speed of the second fan when the output change condition of the second fan is satisfied.

Systems and methods for a vapor compression system including primary actuators, secondary actuators, primary sensors that provide a primary set of system outputs, and secondary sensors that provide a secondary set of system outputs. A primary controller receives the primary set of system outputs, and produces a primary set of control inputs for the primary actuators, to regulate one or more zone temperatures to set-points and to regulate one or more critical process variables to set-points. A secondary controller receives the secondary set of system outputs, and produces a secondary set of control inputs, to minimize an overall system power consumption. The secondary inputs may include set-points to the primary controller. The primary outputs may include estimates of critical process variables that are used as inputs to the secondary controller.

An ice making machine may include an ice tray having a plurality of recessed parts and a cold air duct having a cold air inflow port connected with a cold air supply port and one cold air outlet port facing the ice tray on an upper side. A size of the cold air outlet port is smaller than a size of an ice making face of the ice tray having a contour which includes the plurality of the ice making recessed parts along edges of openings of the plurality of the ice making recessed parts, and the cold air outlet port faces a center portion of the ice making face. It is preferable that an opening area of the cold air outlet port is 50% or less of an area of the ice making face and/or is smaller than an opening area of the cold air inflow port.