Water heater with wireless communication part

A water heater, comprising:

• a communication part for short-range wireless communication with an external device;
• and
• a controller that controls transmission output of the short-range wireless communication performed by the communication part,
• wherein the communication part is configured to automatically authenticate the external device to be connected in response to establishment of communication connection of the short-range wireless communication,
• the controller sets the transmission output to first output before establishment of communication connection with the external device, and increases the transmission output from the first output to second output in response to communication connection with the external device being established, and further
• maintains the transmission output at the second output and stands by for reconnection with the external device until a reference time elapses in response to communication connection with the external device once communicatively connected being disconnected, and decreases the transmission output from the second output to the first output in a case where the reconnection is not established even after the reference time elapses.