Abstract: Disclosed herein are evaporator assemblies for heat pump systems. The evaporator units can comprise a housing defining an interior chamber, an air inlet and an air outlet. The air inlet and the air outlet can form an air flow path through the interior chamber, and an evaporator unit can be positioned within the interior chamber such that the air flow path contacts the evaporator unit. The air inlet having a semi-circular cross section through which air flows into the interior chamber, the semi-circular cross section having a straight edge and a curved edge. A velocity magnitude of the air flowing from the air inlet into contact with the evaporator unit can deviate less than 0.1 m/s from the average air velocity across the surface area of the evaporator.

Abstract: A heat pump water heater can include a refrigerant circuit, an evaporator coil in fluid communication with the refrigerant circuit, a fan configured to move air across the evaporator coil, one or more temperature sensors, a heating element located proximate an air flow path between the fan and the evaporator, and a controller. The controller can be configured to receive temperature data from the one or more temperature sensors and, in response to the temperature data, output instructions for the fan to move air across the heating element to the evaporator coil.

Abstract: Disclosed herein are evaporator assemblies for heat pump systems. The evaporator units can comprise a housing defining an interior chamber, an air inlet and an air outlet. The air inlet and the air outlet can form an air flow path through the interior chamber, and an evaporator unit can be positioned within the interior chamber such that the air flow path contacts the evaporator unit. The air inlet having a semi-circular cross section through which air flows into the interior chamber, the semi-circular cross section having a straight edge and a curved edge. A velocity magnitude of the air flowing from the air inlet into contact with the evaporator unit can deviate less than 0.1 m/s from the average air velocity across the surface area of the evaporator.

Abstract: A heat pump water heater can include a water tank and a refrigerant circuit that can be in fluid communication with an evaporator coil, a condenser coil, and a compressor. The heat pump water heater can include a fan configured to move air across the evaporator coil, a temperature sensor, and a controller. The controller can be configured to receive temperature data from the temperature sensor and, in response to the temperature data indicating a temperature less than a predetermined temperature threshold, output instructions for the compressor to deactivate and the fan to move air across the evaporator coil.

Abstract: Disclosed herein is a water heating system including a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on one or more algorithms and measurements made by the first and second temperature sensors.

Abstract: A water heater and a cover assembly for the water heater is provided. The water heater includes a mixing valve disposed in fluid communication with each of a hot water conduit and a cold water pipe, to regulate temperature of hot water received from the hot water conduit. The cold water pipe branches from a cold water conduit and extends along a longitudinal axis of the tank to connect with the mixing valve. The cover assembly is mounted on a tank of the water heater. The cover assembly includes a first cover to conceal the cold water pipe, and a second cover to conceal the mixing valve and the hot water conduit extending between the tank and the mixing valve. The second cover is removably coupled to the first cover via one or more coupling elements.

Abstract: Air recirculation systems for heat pumps are disclosed. The air recirculation systems include a heat pump subsystem and a recirculation subsystem. The recirculation subsystem can include one or more arms that direct cool, dehumidified air flowing from the heat pump subsystems back to air inlets. The recirculation subsystems can transition from open to closed configurations either manually or via motors. The air recirculation systems can include a controller that outputs a control signal to the motors to open or close the recirculation subsystems. The control signals can be based on temperature data, current data, and the like.

Abstract: A fluid heating device comprising a heat pump and an electric heating element can include a system and method that can receive current data from a current sensor and temperature data from a temperature sensor, determine whether the current is greater than or equal to a threshold current and whether the temperature is greater than or equal to a threshold temperature, and output a control signal to heat the fluid using the heat pump only or the electric heating element only based on the current data and the temperature data.

Abstract: A retrofit heat pump system for a water heater is disclosed. The heat pump system includes a plurality of evaporators to increase the efficiency of heat exchange for the system. The system can also include a plurality of condenser circuits used to heat the water of an existing water tank. A fan disposed in a housing of the heat pump system can draw air across the plurality of evaporators and exhaust cool air external to the heat pump system. The cool air can be exhausted into duct work associated with an air conditioning system of the home. The disclosure also describes a refrigerant distributor for providing uniform liquid refrigerant to the plurality of evaporators.

Abstract: The disclosed technology includes systems and methods for operating a fluid heating device comprising a heat pump and an electric heating element. The disclosed technology can include a system and method that can receive current data from a current sensor and temperature data from a temperature sensor, determine whether the current is greater than or equal to a threshold current and whether the temperature is greater than or equal to a threshold temperature, and output a control signal to heat the fluid using the heat pump only or the electric heating element only based on the current data and the temperature data.

Abstract: A heat pump water heater can include a water tank and a refrigerant circuit that can be in fluid communication with an evaporator coil, a condenser coil, and a compressor. The heat pump water heater can include a fan configured to move air across the evaporator coil, a temperature sensor, and a controller. The controller can be configured to receive temperature data from the temperature sensor and, in response to the temperature data indicating a temperature less than a predetermined temperature threshold, output instructions for the compressor to deactivate and the fan to move air across the evaporator coil.

Abstract: The disclosed technology includes systems and methods for operating a fluid heating device comprising a heat pump and an electric heating element. The disclosed technology can include a system and method that can receive current data from a current sensor and temperature data from a temperature sensor, determine whether the current is greater than or equal to a threshold current and whether the temperature is greater than or equal to a threshold temperature, and output a control signal to heat the fluid using the heat pump only or the electric heating element only based on the current data and the temperature data.

Abstract: Disclosed herein are evaporator assemblies for heat pump systems. The evaporator units can comprise a housing defining an interior chamber, an air inlet and an air outlet. The air inlet and the air outlet can form an air flow path through the interior chamber, and an evaporator unit can be positioned within the interior chamber such that the air flow path contacts the evaporator unit. The air inlet having a semi-circular cross section through which air flows into the interior chamber, the semi-circular cross section having a straight edge and a curved edge. A velocity magnitude of the air flowing from the air inlet into contact with the evaporator unit can deviate less than 0.1 m/s from the average air velocity across the surface area of the evaporator.

Abstract: Disclosed herein is a water heating system including a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on one or more algorithms and measurements made by the first and second temperature sensors.

Abstract: A water heating system can include a water heater having a tank, and a first temperature sensor disposed toward a top end of the tank to measure a first temperature and a second temperature sensor disposed toward a bottom end of the tank to measure a second temperature. The water heating system can further include a controller communicably coupled to the first temperature sensor and the second temperature sensor, where the controller determines an amount of heated water in the tank based on a plurality of algorithms and measurements made by the first and second temperature sensors. The plurality of algorithms solves for at least one calculated temperature for at least one point between a first location of the first temperature sensor and a second location of the second temperature sensor, where the at least one calculated temperature is used to determine the amount of heated water in the tank.

Abstract: A water heater and a cover assembly for the water heater is provided. The water heater includes a mixing valve disposed in fluid communication with each of a hot water conduit and a cold water pipe, to regulate temperature of hot water received from the hot water conduit. The cold water pipe branches from a cold water conduit and extends along a longitudinal axis of the tank to connect with the mixing valve. The cover assembly is mounted on a tank of the water heater. The cover assembly includes a first cover to conceal the cold water pipe, and a second cover to conceal the mixing valve and the hot water conduit extending between the tank and the mixing valve. The second cover is removably coupled to the first cover via one or more coupling elements.

Abstract: A conduit fitting for an exhaust duct includes a conduit and a condensate trap. The conduit fitting defines an interior space partitioned into an upper conduit and a lower condensate reservoir. The condensate reservoir can be configured to contain a neutralizing agent for neutralizing acidic condensate prior to it exiting the reservoir.

Abstract: A conduit fitting for an exhaust duct includes a conduit and a condensate trap. The conduit fitting defines an interior space partitioned into an upper conduit and a lower condensate reservoir. The condensate reservoir can be configured to contain a neutralizing agent for neutralizing acidic condensate prior to it exiting the reservoir.