| 摘要 |
PURPOSE:To carry out the temperature control excellent in a transient property and in a wide range by carrying out the throttle control mainly due to a feed forward control in a case where a gas burner is in a range where the gas burner can be throttled upper than the minimum combustion quantity, and switching the throttling control to the feedback control when a gas proportion valve is throttled up to a minimum combustion quantity of the burner and gets out of the range where the gas proportion valve can be throttled to carry out a flashing control. CONSTITUTION:When water is passed through a heat exchanger 21 by opening a water supply top, a signal for detecting the water supply temperature and the water quantity is first supplied to a control part 31, and a combustion of (set temperature-supply-water temperature) X incoming water quantity is carried out at the control part 31. In a case where the computation output is in a range where the gas burner can be throttled upper than the minimum combustion quantity thereof, a second control part 34 is connected to the gas proportion valve 23. The gas proportion valve 23 is throttled and controlled proportionally in correspondence to the variation in the supply water temperature and the water quantity, and the hot water supply temperature is maintained at a predetermined value. Upon this occasion, when the water supply temperature increases and further the quantity of water decreases, the input quantity of the gas proportion valve 23 gradually decreases to throttle the gas quantity, and when the gas quantity is throttled to the minimum combustion quantity of the gas burner 22, a switch 32 is changed over by the control part 31, and the gas proportion valve 23 and the like are controlled by the first control part 33. |
