| 摘要 |
PURPOSE:To obtain a set supply hot water temperature as quick as possible by seeking for an amount of passing water of a first heat exchanger computing the amount of a gas for heating the passing water to a set supply hot water temperature, transmitting a control signal to a gas control value, and computing the gas amount required for continuance and maintenance of the supply hot water temperature based on a signal from a supply hot water temperature thereby to control the gas control valve. CONSTITUTION:A first heat exchanger 2 is a heat exchanger having a small heat capacity, and reaches a thermal equilibrium in an extremely short period of time in the case of an initial ignition. A water temperature detecting sensor 4 disposed at the outlet of the first heat exchanger 2 displays a predetermined value in a short time. A controller 8 conducts regular prepurge, ignition, flame detection and the like, and has a function to compute the amount of passing water from the gas amount or a gas control valve current which is a signal corresponding thereto and signals from the water temperature detecting sensor 4 and a hot water temperature detecting sensor 5, another function to compute the necessary gas amount from the amount of passing water, the water temperature detecting sensor 4 and the set supply hot water temperature, and further another function to impart a gas control valve current corresponding to the necessary gas amount. The gas control valve 9, is set at a predetermined gas amount at the time of ignition by the controller 8.
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