A method for controlling a water heater is provided. The method includes: controlling operation of a blower when a first condition is satisfied; and controlling an air outlet to be partially or fully opened according to a first parameter or a first instruction. Furthermore, a device for controlling a water heater is provided, including a processor and a memory having program instructions stored thereon. When the program instructions are executed, the processor performs the method for controlling the water heater. Moreover, the water heater is provided, including a housing, a blower, an air-out channel, a heating part, and the device for controlling the water heater.