| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a water service freezing preventive device capable of checking the existence of disconnection of a water service freezing preventive heater, regardless of ON/OFF of a thermoswitch.SOLUTION: A water service freezing preventive device 1 comprises: an electric conduction display light emitting diode L1 connected in parallel to a water service freezing preventive heater 21; and an automatic switching type changeover switch 15 having a common contact point terminal 15a connected to a first power supply line 13 from a power source plug 11, an always closed contact point terminal 15b connected via a temperature sensitive switch 16 to an anode of the electric conduction display light emitting diode L1 and an always opening contact point terminal 15c connected via a disconnection display light emitting diode L2 to the anode of the electric conduction display light emitting diode L1. The anode of the electric conduction display light emitting diode L1 and the anode of the disconnection display light emitting diode L2 are connected.</p> |
