Abstract: A heat pump system includes a refrigerant circuit and a controller. In a heating operation, the usage-side expansion valve is controlled so that a degree of subcooling of outlet refrigerant of the usage-side heat exchanger is equal to a predetermined target degree of subcooling. In a refrigerant recovery control, the heat-source-side expansion valve is controlled so that a degree of superheat of outlet refrigerant of the heat-source-side heat exchanger is equal to a predetermined target degree of superheat, the predetermined target degree of superheat is changed so that the outlet refrigerant of the heat-source-side heat exchanger is wet when the usage-side expansion valve is opened greater than a predetermined opening degree at a start of refrigerant recovery, and change in the predetermined target degree of superheat is cancelled when the usage-side expansion valve is closed smaller than a predetermined opening degree at an end of refrigerant recovery.

Abstract: A refrigerant circuit includes a compressor, a heat source-side heat exchanger, and a usage-side heat exchanger capable of heating an aqueous medium. An aqueous medium circuit includes a circulation pump and the usage-side heat exchanger, and is connected to aqueous medium devices. An auxiliary heat source is provided at an outlet side of the usage-side heat exchanger in the aqueous medium circuit to further heat the aqueous medium. A heating capability computation unit computes a heating capability of the aqueous medium devices based on an operating state quantity of constituent devices or refrigerant flowing through the refrigerant circuit. A circulation flow rate computation unit computes a circulation flow rate of the aqueous medium based on an outlet/inlet temperature difference and the heating capability. A prediction unit predicts an outlet temperature of the aqueous medium in the auxiliary heat source based on the circulation flow rate and heat source capability information.

Abstract: A heat pump system includes a heat source unit, a usage-side unit, and a usage-side controller. The heat source unit has a heat source-side compressor for compressing a heat source-side refrigerant, and a heat source-side heat exchanger capable of functioning as an evaporator of the heat source-side refrigerant. The usage-side unit is connected to the heat source unit and has a capacity-variable-type usage-side compressor for compressing a usage-side refrigerant, a usage-side heat exchanger capable of functioning as a radiator of the heat source-side refrigerant and functioning as an evaporator of the usage-side refrigerant, and a refrigerant-water heat exchanger capable of functioning as a radiator of the usage-side refrigerant and heating an aqueous medium. The usage-side controller performs usage-side capacity variation control for incrementally varying the operating capacity of the usage-side compressor during a usual operation.

Abstract: A heat pump system includes a refrigerant circuit and a controller. The refrigerant circuit has usage units connected to a heat source unit. The usage units have first usage-side heat exchangers and second usage-side heat exchangers. The heat source unit has heat-source-side heat exchanger and a compressor. The controller causes the heat-source-side heat exchanger to function as an evaporator or as a radiator in accordance with an overall heat load of the usage units when the heating operation or the cooling operation has been set for each of the usage units. The aqueous medium is heated by heat radiation of the refrigerant in the first usage-side heat exchangers in the heating operating, and is cooled by evaporation of the heat-source-side refrigerant in the second usage-side heat exchangers in the cooling operation.

Abstract: A heat pump system includes a heat-source-side refrigerant circuit and a controller. The heat-source-side refrigerant circuit has a plurality of usage units having usage-side heat exchangers. The plurality of usage units are connected to a heat source unit having a plurality of heat-source-side heat exchangers and a heat-source-side compressor configured to compress a heat-source-side refrigerant. The controller causes the plurality of heat-source-side heat exchangers to function as evaporators and radiators of heat-source-side refrigerant to perform an air-cooling operation and an air-warming operation using an aqueous medium. The heat pump system operates so that the heat-source-side condensing temperature is below 40° C. in the case that an outside air temperature is 25° C. or lower and the cooling and heating operations coexist.

Abstract: A heat source unit has a capacity-variable heat source-side compressor and a heat source-side heat exchanger which functions as a radiator of refrigerant. Usage units are connected to the heat source unit and have usage-side heat exchangers, respectively, which function as evaporators of refrigerant and cool an aqueous medium. An operating capacity controller controls the capacity of the heat source-side compressor so that evaporation temperature of refrigerant of each of the usage-side heat exchangers reaches a first target evaporation temperature. A decision unit calculates second target evaporation temperatures at which outlet temperatures of the aqueous medium in the usage-side heat exchangers of the respective operating usage units reach predetermined set temperatures, and decides a minimum value of the second target evaporation temperatures as the first target evaporation temperature.

Abstract: A heat pump system includes a refrigerant circuit, an inlet temperature sensor measuring a heat exchanger inlet temperature of an aqueous medium in a usage-side heat exchanger of the refrigerant circuit, an outlet temperature sensor measuring a heat exchanger outlet temperature of the aqueous medium in the usage-side heat exchanger, a variable-capacity circulating pump circulating the aqueous medium inside a hot-water circuit of a loop, and a controller. The controller controls refrigerant-side circulation rate in the refrigerant circuit to bring a temperature of the aqueous medium at the outlet of the usage-side heat exchanger to a targeted first target temperature, and operating capacity of the circulating pump to bring a medium temperature differential of the aqueous medium between the outlet and the inlet of the usage-side heat exchanger to a targeted second target temperature differential.

Abstract: A heat pump system includes: a heat-source-side refrigerant circuit having a heat-source-side compressor, a first usage-side heat exchanger operable as a radiator of heat-source-side refrigerant, and a heat-source-side heat exchanger operable as an evaporator of heat-source-side refrigerant; and a usage-side refrigerant circuit having a usage-side compressor arranged to compress usage-side refrigerant with a pressure of the usage-side refrigerant corresponding to a saturated gas temperature of 65° C. that is 2.8 MPa or less at gauge pressure, a refrigerant-water heat exchanger operable as a radiator of usage-side refrigerant to heat an aqueous medium, and a first usage-side heat exchanger operable as an evaporator of usage-side refrigerant by the radiation of heat-source-side refrigerant. The weight of usage-side refrigerant enclosed in the usage-side refrigerant circuit is one to three times the weight of refrigeration machine oil enclosed to lubricate the usage-side compressor.

Abstract: A heat pump system includes: a heat-source-side refrigerant circuit having a heat-source-side compressor, a first usage-side heat exchanger operable as a radiator of heat-source-side refrigerant, and a heat-source-side heat exchanger operable as a radiator of heat-source-side refrigerant; and a usage-side refrigerant circuit having a usage-side compressor, a refrigerant/water heat exchanger operable as a radiator of usage-side refrigerant to heat an aqueous medium, and the first usage-side heat exchanger operable as an evaporator of usage-side refrigerant by radiation of heat-source-side refrigerant.

Abstract: A heater for a room heating system includes a heating element, a housing having the heating element disposed therein, a thermal distribution fluid inlet into the housing, a thermal distribution fluid outlet from the housing, and at least one safety feature connection. The housing is arranged to contain thermal distribution fluid as the thermal distribution fluid follows a flow path from the thermal distribution fluid inlet to the thermal distribution fluid outlet and over the heating element. The at least one safety feature connection includes a passage through the housing.

Abstract: A heating installation includes a heat pump, heating fluid piping passing through a condenser of the heat pump to exchange heat between refrigerant and heating fluid, first and second objects heated by the heating fluid to first and second set temperatures, a valve switchable between first and second positions to supply heating fluid to the first and second objects, sensors detecting first and second actual temperatures at the first and second objects, and a control. The heat pump also has an evaporator, a compressor and an expansion device. The control in a demand dependent mode, is configured to determine a first demand based on the first set and actual temperatures and a second demand based on the second set and actual temperatures, and is configured to switch the valve to the first and second positions based on comparison of the first and second demands. A method for controlling a heating installation heats the first or second object based on such a comparison.