Abstract: The disclosed technology includes systems and methods for a heat pump water heater. The disclosed technology can include a heat pump water heater system having an evaporator, a condenser, a vapor injection line, a compressor, and a multi-fluid heat exchanger. The vapor injection line can include an expansion valve to transition refrigerant received from the condenser at a first pressure to a second pressure. The compressor can be configured to circulate refrigerant through the condenser, the multi-fluid heat exchanger, the vapor injection line, and the evaporator. The multi-fluid heat exchanger can be configured to receive refrigerant at a first pressure from the condenser, refrigerant at a second pressure from the vapor injection line, and water. The multi-fluid heat exchanger can further facilitate heat transfer between the refrigerants at the first and second pressures and the water to preheat the water before the water is passed through the condenser.

Abstract: The disclosed technology can include a system for monitoring and detecting a fault in a fluid storage tank. A sensor can be located in, on, or proximate the fluid storage tank and can be configured to detect waveforms produced by the fluid storage tank in response to strain. The sensor can convert such waveforms into electrical signals and transmit such electrical signals in the form of vibration data to a controller. The controller can compare the vibration data to stored data, and based on such comparison, determine if a fault is present in the fluid storage tank.

Abstract: The disclosed technology can include a system for monitoring and detecting a fault in a fluid storage tank. A sensor can be located in, on, or proximate the fluid storage tank and can be configured to detect waveforms produced by the fluid storage tank in response to strain. The sensor can convert such waveforms into electrical signals and transmit such electrical signals in the form of vibration data to a controller. The controller can compare the vibration data to stored data, and based on such comparison, determine if a fault is present in the fluid storage tank.