FREEZE PREVENTING EQUIPMENT OF WATER HEATER

PURPOSE:To obtain freeze preventing equipment of a water heater which enables prevention of freeze even when a sensor detecting an atmospheric temperature fails. CONSTITUTION:Freeze preventing equipment of a water heater which has an instantaneous heat exchanger 2 and a burner 3 provided in a case 1 and heaters 9 and 10 for preventing freeze and an atmospheric temperature sensor 11 disposed therein and wherein a heating operation by the heaters 9 and 10 is started when an automatic freeze preventing switch is turned ON, on condition that the atmospheric temperature sensor 11 detects that a prescribed temperature is not reached. With the automatic freeze preventing switch turned ON, first it is determined whether the atmospheric temperature sensor 11 is normal or not, on the basis of a signal level sent from the atmospheric temperature sensor 11. A controller 12 which gives a command to start a prescribed heating operation by the heaters 9 and 10 for preventing freeze when the atmospheric temperature sensor 11 is normal and when it detects that the prescribed temperature is not reached and also gives the command to start the prescribed heating operation by the heaters 9 and 10 irrespective of conditions of temperature when the sensor is not normal, is provided.