A building ventilator to provide a supply of air into a building comprises an external inlet port and a separate external outlet port and an internal inlet port and a separate internal outlet port to allow respective airstreams to flow into and out of the ventilator respectively at an exterior and at an interior of the building; a heat exchanger mounted in the flow paths between the external and internal inlet and outlet ports. The ventilator is configured to drive an airflow from the external inlet port through the heat exchanger and out of the ventilator via the internal outlet port; and to drive an airflow from the internal inlet port through the heat exchanger and out of the ventilator via the external outlet port. The ventilator comprises a heating element mounted in the air flow path between the external inlet port and the heat exchanger.

A building ventilator to provide a supply of air into a building comprises an external inlet port and a separate external outlet port and an internal inlet port and a separate internal outlet port to allow respective airstreams to flow into and out of the ventilator respectively at an exterior and at an interior of the building; a heat exchanger mounted in the flow paths between the external and internal inlet and outlet ports. The ventilator is configured to drive an airflow from the external inlet port through the heat exchanger and out of the ventilator via the internal outlet port; and to drive an airflow from the internal inlet port through the heat exchanger and out of the ventilator via the external outlet port. The ventilator comprises a heating element mounted in the air flow path between the external inlet port and the heat exchanger.

When the temperatures of outdoor heat exchangers 23a and 23b detected by outdoor heat exchanger temperature sensors 57a and 57b become equal to or higher than 5 degrees C. and the sucking superheating degrees of compressors 21a and 21b become equal to or lower than 0 degrees C. while an air conditioning apparatus 1 is performing the reverse defrosting operation, the reverse defrosting operation is stopped and the heating dominant operation is resumed. At this time, the total operating times of the compressors 21a and 21b are reset. The sucking superheating degrees of the compressors 21a and 21b are obtained by subtracting the low pressure saturation temperatures calculated from the sucking pressures of the compressors 21a and 21b, from the temperatures of the refrigerants sucked into the compressors 21a and 21b which temperatures are detected by the sucking temperature sensors 54a and 54b.

When the temperatures of outdoor heat exchangers 23a and 23b detected by outdoor heat exchanger temperature sensors 57a and 57b become equal to or higher than 5 degrees C. and the sucking superheating degrees of compressors 21a and 21b become equal to or lower than 0 degrees C. while an air conditioning apparatus 1 is performing the reverse defrosting operation, the reverse defrosting operation is stopped and the heating dominant operation is resumed. At this time, the total operating times of the compressors 21a and 21b are reset. The sucking superheating degrees of the compressors 21a and 21b are obtained by subtracting the low pressure saturation temperatures calculated from the sucking pressures of the compressors 21a and 21b, from the temperatures of the refrigerants sucked into the compressors 21a and 21b which temperatures are detected by the sucking temperature sensors 54a and 54b.

A refrigeration cycle apparatus including a refrigerant circuit including a compressor, an indoor heat exchanger, an expansion device, an outdoor heat exchanger, an outside air temperature sensor, and a controller configured to perform a hot gas defrosting operation and a reverse-defrosting operation based on a temperature obtained by the outside air temperature sensor. In the hot gas defrosting operation, hot gas discharged from the compressor without passing through the indoor heat exchanger is supplied to the outdoor heat exchanger. In the reverse-defrosting operation, refrigerant passing through the indoor heat exchanger is supplied from the compressor to the outdoor heat exchanger. The controller has at least a mixed defrosting operation mode in which the hot gas defrosting operation and the reverse-defrosting operation are performed in sequence. The controller is configured to start the mixed defrosting operation mode when the temperature obtained by the outside air temperature sensor satisfies a preset condition.

An apparatus that includes a vessel. The vessel is partially filled with a product to be defrosted. The vessel rotates about an inclined axis. The vessel includes means to move the product during defrosting. The apparatus includes a temperature-measurement-means located at partially inside the vessel to determine a surface temperature of the product and a temperature of liquid surrounding the product without contacting the product and without contacting the liquid. The temperature-measurement-means remain stationary while the vessel rotates.

An apparatus that includes a vessel. The vessel is partially filled with a product to be defrosted. The vessel rotates about an inclined axis. The vessel includes means to move the product during defrosting. The apparatus includes a temperature-measurement-means located at partially inside the vessel to determine a surface temperature of the product and a temperature of liquid surrounding the product without contacting the product and without contacting the liquid. The temperature-measurement-means remain stationary while the vessel rotates.

An air conditioner for a vehicle includes a cycle switching device. The cycle switching device switches a refrigerant cycle between a heating circuit, in which refrigerant flows through a heating heat exchanger, and a cooling circuit, in which refrigerant flows through a cooling heat exchanger. The air conditioner further includes an air conditioning controller, which controls the cycle switching device and includes a defroster control portion. The defroster control portion increases a temperature of air blown into the vehicle compartment through a defroster air outlet by a predetermined degree while keeping the refrigerant cycle at a state of the heating circuit for a predetermined time, when a defrosting operation is commanded to be performed during the heating circuit.

A method of operating a heat pump system is provided, the heat pump system having at least a controller and configured to operate at least two defrost cycles. The method comprises receiving, at the controller, weather data for a defined geographic area proximate to an installed location of the heat pump system; and selecting, based on said weather data, one of the at least two defrost cycles.

In various implementations, an ice sensor may include heater(s), ice accumulation surface(s), and/or temperature sensor(s). During operation, heat from a heater may be provided to an ice accumulation surface and a temperature sensor(s) may determine temperature(s) of the ice accumulation surface. A determination of whether ice is present on the ice sensor may be based at least partially on the determined temperature(s).