MIXING TYPE WATER BOILER

PURPOSE:To stop only a mixing valve and to continue function of other water boiler, by a method wherein, in a mixing valve being regulatable through remote control, where an ON-signal to a motor lock safety circuit from a servo amplifier is continued for a specified time or more, a power source thereto is brought into an OFF-state. CONSTITUTION:During normal operation, with an operation switch 10 turned ON, a transistor 25 is energized through resistors 19-21, a transistor 24 is energized through resistors 22 and 23, and a power source 16 is fed to a servo amplifier 26 and a motor drive circuit 27. Since, when a servo motor 33 is locked, an ON-signal from the servo amplifier 26 to a motor lock safety circuit 28 is continued for a specified time or more, a lock safety timer is timed out, and a voltage is applied to resistors 29 and 30. As a result, a transistor 31 is turned ON, transistors 24 and 25 are turned OFF, and the feed of the power source to the servo amplifier 26 and the motor drive circuit 27 is disconnected.