| 摘要 |
PURPOSE:To easily control the water temperature without causing a hunting in the water temperature by controlling the gas flow rate by computing the gas demand from a set water temperature and a set hot water delivery rate based on measured values of water temperature and burning air temperature. CONSTITUTION:A temperature sensor 6 in a feed water line 4, an air temperature sensor 17, a flow meter 7 and a water governor 8 are connected to a controller 20 so that their detected or measured signals may be inputted into the controller 20. A computation is made with temperatures of water and air so obtained and the hot water flow rate and temperature set by a setting unit 26 to first make a judgment whether or not the set values exceeds the capacity of a heat exchanger. If the capacity is exceeded, a command is given to a motor of a motor valve 9 to limit the feed water quantity until the motor valve allows the maximum capacity. On the other hand, if the set values are lower than the maximum capacity of the heat exchanger 3, a command is given from the controller 20 to the motor 25 to limit the gas flow rate, and based on such a command, gas and air flow rates are controlled at the same time. In this manner, the temperature and hot water delivery rate set by the setting unit 26 are realized. |
