Heat pump systems with a gas bypass tank and that operate in both heating and cooling modes are disclosed. The systems include a first splitting valve that can route liquid refrigerant to either the indoor coil or the outdoor coil, depending on whether the heat pump system is in heating or cooling mode. An expansion valve in the system can lower the pressure of liquid refrigerant leaving a condenser, thereby creating a two-phase fluid comprising liquid refrigerant and vaporized refrigerant. The gas bypass tank can separate liquid refrigerant from vaporized refrigerant. The liquid refrigerant can be supplied to the evaporator of the system, while the vaporized refrigerant can be bypassed to a compressor. The first splitting valve can include a first plurality of switching paths that route the separated liquid refrigerant to either the outdoor coil or the indoor coil.

A cooling system includes an evaporator, connected through fluid lines to a first condenser, a second condenser, a compressor, and a thermal expansion valve. One or more valves are arranged in the fluid lines. The one or more valves operated to, in a first mode, circulate fluid between the evaporator the first condenser; in a second mode, circulate the fluid between a) the evaporator and the first condenser, and b) the evaporator, the second condenser, and the thermal expansion valve, and; in a third mode, circulate the fluid between a) the evaporator and the first condenser, and c) the evaporator, the compressor, the second condenser, and the thermal expansion valve.

To provide a defrost system capable of preferable defrosting and prevention of generation of icicles on a casing without installing a brine circuit. A defrost system includes a thermosiphon defrost circuit that is provided by being branched from a circulation line, in which, at the time of defrosting, a CO.sub.2 refrigerant staying inside a fin-tube heat exchanger repeats a two-phase change of a gaseous form and reliquefaction, and which forms a CO.sub.2 circulation path together with the fin-tube heat exchanger; electromagnetic opening/closing valves and that are closed at the time of defrosting and set the CO.sub.2 circulation path to a closed circuit; and a first electric heater arranged above the thermosiphon defrost circuit so as to be adjacent to the thermosiphon defrost circuit, and naturally circulates the CO.sub.2 refrigerant in the closed circuit at the time of defrosting.

A cryocooler includes a compressor, an expander that includes a motor and is driven by the motor, an inverter that controls an operation frequency of the motor, a high pressure line that connects the compressor to the expander such that a working gas is supplied from the compressor to the expander, a low pressure line that connects the compressor to the expander such that a working gas is collected from the expander to the compressor, a pressure measurement unit that is configured to measure pressures of the high pressure line and the low pressure line or to measure a differential pressure between the high pressure line and the low pressure line, and a controller that compares the differential pressure to a target pressure and controls the inverter such that the operation frequency of the motor is increased when the differential pressure exceeds the target pressure.

A heat pump apparatus includes: a refrigerant circuit configured to circulate refrigerant having flammability; a heat medium circuit configured to allow a heat medium to flow therethrough; a heat-medium heat exchanger configured to exchange heat between the refrigerant and the heat medium; an outdoor unit configured to accommodate the refrigerant circuit and the heat-medium heat exchanger; and an indoor unit configured to accommodate a part of the heat medium circuit, the outdoor unit including a refrigerant release valve, the refrigerant release valve being at least one of a pressure relief valve and an air purge valve which are provided in the heat medium circuit, the refrigerant release valve being provided outside a casing of the outdoor unit.

A refrigeration apparatus includes a refrigerant circuit including a utilization unit. The utilization unit includes: a heat exchanger; first and second refrigerant pipes connected to the heat exchanger; and first and second shutoff valves each of whose opening degrees are adjustable and which are respectively provided at the first refrigerant pipe and the second refrigerant pipe. The refrigeration apparatus includes: a refrigerant leakage detector; a refrigerant pressure acquiring part; and a controller configured to adjust the opening degrees of the first shutoff valve and the second shutoff valve. In an alert state where the first shutoff valve and the second shutoff valve are both closed and the refrigerant leakage detector detects the leakage, the controller adjusts the opening degree of at least one of the first and second shutoff valves to open when the pressure of the refrigerant is greater than a predetermined threshold value.

A heat pump device can discharge air in a heat medium circuit regardless of the height positions of two bodies of the heat pump device and prevents refrigerant outflow when the refrigerant enters the heat medium circuit in the liquid heat exchanger. A pump causes the liquid heat medium to flow in a predetermined circulatory direction in a heat medium pipe, and a liquid heat exchanger, a first air vent valve and a second air vent valve are arranged in this order along a circulatory direction.

A cooling system includes an evaporator coil and a compressor fluidly coupled to the evaporator coil. A circulation fan is arranged to direct air through the evaporator coil and through a discharge air duct into a conditioned space. At least one sensor is disposed in at least one of the discharge air duct, the conditioned space, and the evaporator coil. An HVAC controller is electrically coupled to the at least one sensor and electrically coupled to the compressor. The HVAC controller is configured to receive a measurement of an HVAC parameter from the at least one sensor, determine if the HVAC parameter indicates frost formation on the evaporator coil, and, responsive to a determination that the HV AC parameter indicates frost formation on the evaporator coil, raise a saturated suction temperature of the evaporator coil.

A pressure control device for controlling a compressor includes a pressure sensor configured to measure pressure of a pressure line and a processing circuit. The processing circuit is configured to receive the measured pressure of the pressure line from the pressure sensor and control the compressor based on a set-point and the measured pressure. The pressure control device includes a mechanical switch sensitive to the pressure of the pressure line and configured to move between an open position and a closed position responsive to the pressure of the pressure line. Movement of the mechanical switch into one of the open position or the closed position causes the compressor to turn off and overrides the control of the compressor by the processing circuit.

A hot water system includes an electrical water heater for instantly heating up cold water running in pipe. The electrical water heater is installed with a bypass switch for users to switch off the system if necessary. To prevent water damage caused by leaking, a pressure relief valve is installed on the outgoing water pipe of the water heater and a drain saddle valve is installed on the drain pipe. Both valves are connected with a water hose. The hot water system will save a lot of time and clean water while waiting for hot water coming from the main water heater. The system allows the user to access instant hot water safely and achieve a much easier and more comfortable life.