Traditional water heaters are frequently found to be unable to provide sufficient water supply and maintain temperature instability. The thesis develops a high-volume water heater parallel system to cope with this problem. First, multiple cool water storage tanks are employed to store enough cool water. Next, the control valve is activated to heat cool water, when heated is to a setting temperature, the water is then transported to the hot water tank for storage. Finally, the needed heated water is delivered to the faucet or shower nozzle. To prevent instability of temperature and water output, this product employs three devices including an anti-valve, a temperature sensor and an alarming lamp. The backflow barrier is employed to keep water backflow, the temperature sensor is adopted to detect temperature signal, and the alarming lamp shows the status of the heater. The empirically made water heater is credited with maintaining stability of water supply and temperature on the one hand, and interchangeability and life of the water heater on the other hand. Besides, the whole design can make us to understand the knowledge which related to physics, material science and electrical engineering.