To perform exact intimidation operation by an intimidating device when a human detection sensor disposed outdoors detects a person.

A water heater unit 1 disposed outdoors is connected to a remote controller unit 3 disposed indoors via a communication line 2. The water heater unit 1 is provided with a human detection sensor 7 for detecting a person positioned in a area near the water heater unit 1 and a signal connection part of one intimidating device 8 or more for performing intimidation operation by at least either light or a sound when the human detection sensor 7 detects a person, and the intimidating device 8 is connected to the signal connection part. The remote controller unit 3 is provided with an intimidation content setting operating part 4 for setting an intimidation operation content by the intimidating device 8.