Theoretical Calculation and Optimal Design of Gas Water Heater to Realize Zero Waiting for Hot Water

The function between time and water temperature of a gas water heater was established using the heat transfer model, and the aqueous temperature of hot water pipe was calculated. The impact of intelligent water pump system on water conservation was analyzed. Several methods that are effective in shortening the waiting time for hot water are concluded as follows: (1) Increasing the water outlet temperature of the gas water heater; (2) Shortening the water pipe length from the gas water heater to the bathroom faucet; (3) Installing a hot water pipe; (4) Accelerating pumping speed of the hot water circulation pump; (5) Keeping the circulating pump and gas water heater open constantly, and the water circulation being kept in the hot water pipe when hot water is not used.