| 摘要 |
PROBLEM TO BE SOLVED: To quickly make the temperature of hot water reach a target temperature, and to prevent the temperature abnormality of the hot water even when the number of loads to which the hot water is circularly supplied fluctuates. SOLUTION: A PID setting part 24 incorporating a PID memory 25 in which a plurality of PID control constant groups are stored so as to be made correspond to each temperature change rate calculates the change rate of the temperature of hot water detected by a temperature sensor 18, and selects the PID control constant group corresponding to the change rate of the temperature from among those PID control constant groups in the PID memory 25, and outputs the selected PID control constant group to a temperature control part 23. At inputting the selected PID control constant group, the temperature control part 23 changes the PID control constant group used until that time to the selected PID control constant group, and PID-controls the temperature of the hot water by ON/OFF-controlling a heater 17 by using each constant included in the selected PID control constant group.
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