A heat pump system is provided that includes a flow directing system that allows an outdoor heat exchanger to be switchable between a single-pass arrangement and a two-pass arrangement. The heat pump system includes an outdoor heat exchanger, an indoor heat exchanger, and a flow directing system of check valves and piping segments that enable switching of the outdoor heat exchanger between the single-pass and the two-pass arrangement. The outdoor heat exchanger is operable as a two-pass condenser in the cooling mode and as a single-pass evaporator in the heating mode.

An outdoor unit includes a bypass circuit that makes a part of refrigerant that is discharged from a compressor be bypassed to a connecting part at the time of defrosting operation. A control device of the outdoor unit performs control of opening an electromagnetic valve in the bypass circuit based on an water temperature TW (in) in an water inlet and an water temperature TW (out) in an water outlet of an water heat exchanger at the time of the defrosting operation. Further, a control device controls a valve travel of the valve of the third expansion valve in the bypass circuit based on a refrigerant temperature TR (in) in a refrigerant inlet and a refrigerant temperature TR (out) in a refrigerant outlet of the water heat exchanger in a case of the electromagnetic valve being in an open state at the time of the defrosting operation.

A method for defrosting an evaporator of a water heater appliance is provided. The method includes initiating a defrost cycle of the water heater appliance, deactivating a compressor of the water heater appliance during the defrost cycle of the water heater appliance, and operating a fan of the water heater appliance during the defrost cycle of the water heater appliance. A related water heater appliance is also provided.

An automatic plant watering device includes a thermoelectric module with a cold face that can be energized to drop its temperature below 32 degrees F. A condensation member is thermally connected to the cold face and has a wall exposed to ambient air for water vapor to condense on and freeze when the module is energized. A water collection chamber positioned below the exposed wall is configured to hold collected melt water from the exposed wall until a collected melt water temperature has risen above 32 F. A moisture sensor is used to initiate a chilling cycle controlled by a controller to energize the thermoelectric module for a period of time in excess of an hour to cause a build-up of frost on the exposed wall and thereafter to deenergize the thermoelectric module to permit the temperature of the exposed wall to rise above 32 degrees F.

An air conditioner including a compressor including a discharge side; an outdoor heat exchanger configured to exchange heat with outdoor air; a base arranged to support the compressor and the outdoor heat exchanger; a four-way valve arranged between the discharge side of the compressor and the outdoor heat exchanger; a defrost pipe arranged at the base and configured to receive refrigerant discharged from the compressor to supply heat of the refrigerant discharged from the compressor to the base; and a defrost valve arranged on the defrost pipe and configured to adjust a flow rate of the refrigerant flowing through the defrost pipe.