The storage water tank always connect to at least one main energy sources, like solar energy, or heat pump, or gas. Cold water enters the storage water tank from the cold water inlet connection and pushes hot water out through the hot water outlet connection. Thanks to GMO water heater dip tube, it can maximize the hot water delivery. There are one thermostat and heating element in the middile of the storage water tank, it is electric backup. The enamel coating tank is able to prevent the water heater tank from corrosion and install an anode rod to help avoid corrosion. The temperature and pressure relief valve is a safety device designed to open if the water heater temperature or pressure of the tank exceeds certain limits. Water heaters capacity should be large enough to provide adequate hot water during the hot water consumption peak.