Abstract: A water heating system includes: a refrigerant circuit that includes a compressor and in which a refrigerant flows; and a water circuit in which water flows. The refrigerant circuit shares with the water circuit a water heat exchanger that heats the water using the refrigerant discharged from the compressor. The water heat exchanger includes a first heat-exchanging unit in which the refrigerant exchanges heat with the water at a water outlet portion. The refrigerant circuit further includes a heat radiator that is disposed between the compressor and the first heat-exchanging unit and that radiates heat of the refrigerant discharged from the compressor. The heat radiator is configured to radiate heat of the refrigerant to water that flows on an upstream side of the water outlet portion.

Abstract: A hot water supply apparatus includes: a first channel configured to send water in a medium-temperature layer (M) to a heating section; and a second channel configured to return water heated by the heating section to a tank. The second channel has an outflow port at a lower position than an inflow port of the first channel.

Abstract: A controller performs a first operation in which a heat source device directly or indirectly heats water in a first channel of a heat exchanger and a second operation in which the heat source device directly or indirectly cools the water in the first channel of the heat exchanger after the first operation ends.

Abstract: A water heating system includes: a refrigerant circuit that includes a compressor and in which a refrigerant flows; and a water circuit in which water flows. The refrigerant circuit shares with the water circuit a water heat exchanger that heats the water using the refrigerant discharged from the compressor. The water heat exchanger includes a first heat-exchanging unit in which the refrigerant exchanges heat with the water at a water outlet portion. The refrigerant circuit further includes a heat radiator that is disposed between the compressor and the first heat-exchanging unit and that radiates heat of the refrigerant discharged from the compressor. The heat radiator is configured to radiate heat of the refrigerant to water that flows on an upstream side of the water outlet portion.

Abstract: A hot water supply apparatus includes a heat exchanger that heats water for hot water supply, a pressure controller provided in a subsequent stage of the heat exchanger, and a trap that promotes deposition of scale. The pressure controller pressurizes the water for hot water supply. The trap is provided in a subsequent stage of the pressure controller.

Abstract: A controller performs a first operation in which a heat source device directly or indirectly heats water in a first channel of a heat exchanger and a second operation in which the heat source device directly or indirectly cools the water in the first channel of the heat exchanger after the first operation ends.

Abstract: A hot water supply apparatus includes a hot water supply channel. The hot water supply channel includes a heating section configured to heat water and a tank configured to store the water heated by the heating section. The hot water supply channel is configured to execute a first hot water supply operation in a hot water storage state in which a low-temperature layer, a medium-temperature layer, and a high-temperature layer are formed in the tank. The first hot water supply operation includes heating water in the medium-temperature layer to a first temperature by the heating section and supplying the water heated to a hot water supply target.

Abstract: A compressor includes a casing, compression mechanism disposed inside the casing, a discharge tube, a first temperature sensor, and a second temperature sensor. The compression mechanism compresses a sucked refrigerant, and discharges the compressed refrigerant to a refrigerant channel formed in an inner space of the casing. The compressed refrigerant flows from the inner space of the casing to an outside through the discharge tube. The first temperature sensor includes a temperature sensing portion disposed in the refrigerant channel, and directly measuring a temperature of the refrigerant. The second temperature sensor is disposed at a different position from the first temperature sensor. The second temperature sensor measures a temperature of one of a surface of the discharge tube, an inner space of the discharge tube, and a surface of the casing.

Abstract: In a switch device in which four switches are operated by depression of four depressing surfaces which are defined by diagonal lines on a rectangular operating knob, the four switches comprise: four principal contact assemblies which are each arranged in such a manner as to be aligned with one of the depressing surfaces to form part of the switches, and each respective principal contact assembly is turned on when the corresponding depressing surface is depressed; and two common contact assemblies which are arranged at substantially opposite ends of one of the diagonal lines of the operating knob in such a manner that each of the two common contact assemblies is aligned with two adjacent ones of the depressing surfaces to form part of two adjacent switches, and each common contact assembly is turned on by depression of any one of the two adjacent depressing surfaces, which results in a switch device that is simple in construction and low in manufacturing cost.