PURPOSE: To improve an accuracy in setting of an amount of hot water by a method wherein each of water supplying port and hot water supplying port is provided with a temperature sensor, a flow rate sensor is arranged at either at least one of the water supplying port or hot water supplying port, an input information is applied to a control unit and an amount of hot water discharged from the hot water supplying port is automatically calculated.

CONSTITUTION: A temperature of flowing water is measured by a water temperature sensor 13 at a water supplying port 3, a water temperature at the water plug 19 is measured, a temperature of hot water flowing out of the hot water outlet 4 is measured by a hot water temperature sensor 14, resulting in measuring of a hot water temperature at the hot water discharging plug 18. At the same time, a flow rate of hot water is sensed by a flow rate sensor 12 arranged at the water supplying port 3, both a thermal energy applied to the bath tub 20 from the hot water discharging plug 18 and the water discharging port 19 per unit time can be calculated. One of the remote control units 8 has a hot water temperature setting button 16 and a hot water volume setting button 17, and a total thermal energy of supplied hot water for the bath tube 20 can be determined by the input. In this way, if the desired amount of thermal energy can be set and the water supplying temperature and the hot water temperature can be measured, a solenoid valve 21 at hot water side and a solenoid valve 22 at water side are closed, thereby an automatic hot water feeding can be performed.