Embodiments include heat pump systems with gas bypasses and related methods. In one embodiment, a system may include a gas bypass tank having a bypass inlet, a liquid outlet, and a vapor outlet, and a first splitting valve having a first splitter outlet in fluid communication with the bypass inlet, a first splitter inlet in fluid communication with the liquid outlet, and a first switching path configured to switch between a first conduit path in fluid communication with a first coil system and a second conduit path in fluid communication with a second coil system.

In a split system heat pump cooling and heating system, an auxiliary hot water storage tank is provided as an energy storage bank. Two sets of coils run through this storage tank, a first set carrying hot refrigerant from the heat pump to deposit energy and a second set carrying hot potable water to remove energy. Valve and switch matrixes are operated at the heat pump to provide hot potable water from the energy storage bank during both normal space heating and cooling operations of the heat pump.

An air conditioning system can be toggled between a heating mode, in which heat is withdrawn from a source (e.g., a geothermal source) and deposited into a conditioned space (e.g., a building), and a cooling mode, in which heat is withdrawn from the conditioned space and deposited into the source. The air conditioning system uses a combination of efficiency-enhancing technologies, including injection of superheated vapor into the system's compressor from an economizer circuit, adjustable compressor speed, the use of one or coaxial heat exchangers and the use of electronic expansion valves that are continuously adjustable from a fully closed to various open positions. A controller may be used to control the system for optimal performance in both the heating and cooling modes, such as by disabling the economizer circuit and vapor injection when the system is in the cooling mode.

When a controller receives an instruction for a heating operation, the controller switches an operation mode of a refrigeration cycle apparatus between a heating operation mode and an oil recovery operation mode. The heating operation mode is a mode to circulate refrigerant in a refrigerant circuit such that the refrigerant flows through a gas extension pipe in a gas phase state. The oil recovery operation mode is a mode to circulate the refrigerant in the refrigerant circuit such that the refrigerant flows in the gas extension pipe in a gas-liquid two-phase state. The direction in which the refrigerant flows in the gas extension pipe in the oil recovery operation mode is opposite to that in which the refrigerant flows in the gas extension pipe in the heating operation mode.

An air-conditioning apparatus includes a compressor, an indoor heat exchanger, a first outdoor heat exchanger and a second outdoor heat exchanger, a valve between the second outdoor heat exchanger and the indoor heat exchanger switching between an opened state and a closed state, a temperature sensor detecting a temperature of refrigerant that flows into the second outdoor heat exchanger and liquefies, and a condensing-temperature detection device, wherein during first cooling operation in which the first outdoor heat exchanger functions as a condenser, the indoor heat exchanger functions as an evaporator, and the valve is in the closed state, when a comparative temperature becomes equal to or higher than a prescribed temperature, the air-conditioning apparatus switches to second cooling operation in which the valve is brought into the opened state, the comparative temperature being a value obtained by subtracting a temperature detected by the temperature sensor from the condensing temperature.

An HVAC system includes a reversing valve configured to receive compressed refrigerant and direct the refrigerant based on an operating mode. One or more suction-side sensors measure suction-side properties associated with refrigerant, including a suction-side temperature and a suction-side pressure. One or more liquid-side sensors measure liquid-side properties associated with the refrigerant. A controller monitors the suction-side pressure and liquid-side pressure and determines a ratio of the liquid-side pressure to the suction-side pressure. The controller further determines whether the suction-side temperature has an increasing trend. If the suction-side temperature has the increasing trend, the reversing valve is determined to be in an equalizing configuration. The equalizing configuration corresponds to a configuration in which the refrigerant provided from the outlet of the compressor is directed to the inlet of the compressor without first being directed to other components of the HVAC system.

A heat pump system includes a compression device 12, a heat rejecting heat exchanger 14, an expansion device 18 and a heat absorbing heat exchanger 16; wherein the expansion device 18 provides a controllable degree of expansion. The heat pump system is operated in accordance with a method including determining a temperature indicative of frosting conditions on an exterior surface of the heat absorbing heat exchanger 16; operating the heat pump system in a first mode if the temperature indicative of frosting conditions is above a threshold value, and operating the heat pump system in a second mode if the temperature indicative of frosting conditions is within a range of temperatures that is below the threshold value.

A reversible flow heat exchange system includes a heat exchanger system that includes a canister configured to receive a first fluid from a machine and a heat exchanger disposed within the canister. The reversible flow heat exchange system also includes a cooling system coupled to the heat exchanger and configured to circulate a second fluid between the heat exchanger system and the cooling system and a reversing valve coupled to the heat exchanger and configured to selectively direct a flow of the first fluid in a first direction through the canister and in a second direction through the canister that is opposite the first direction.

Systems and methods for controlled subcooling of working fluid in a heating, ventilation, air conditioning and refrigeration (HVACR) system through a suction line heat exchanger are disclosed. The suction line heat exchanger may receive a first fluid flow travelling to a suction of the compressor in the HVACR system and second flow of working fluid that is travelling from a heat exchanger receiving the discharge of the compressor to an expansion device. Superheating of the first working fluid may be determined based on temperature measurements prior to and following the suction line heat exchanger. The superheating may be used to control the quantity of the second flow of working fluid introduced into the suction line heat exchanger, for example to maintain superheat that is below a threshold value. These systems may include chillers and heat pump systems, and methods may be applied to chillers or heat pump systems.

An air-conditioning apparatus includes a refrigerant circuit formed by connecting, with pipes, a compressor, a first refrigerant flow switching device, a heat-source-side heat exchanger, an expansion device, and a plurality of intermediate heat exchangers. A heat medium circuit is formed by connecting, with pipes, a plurality of pumps configured to pressurize and circulate the heat medium subjected to heat exchange in the plurality of intermediate heat exchangers, a plurality of use-side heat exchangers each configured to exchange heat between the heat medium and air in an air-conditioned space, and a heat-medium flow switching/control device configured to switch which of the heat medium is to be allowed to flow into and out of each of the use-side heat exchangers; and a controller configured to perform processing for controlling the switching performed by the heat-medium flow switching/control device, in accordance with a capacity of each of the use-side heat exchangers.