This fan will be factory equipped with a thermal on/off switch. This switch is designed to turn the fan on at 80° Fahrenheit, with a less 15° shutoff. Example: Room temperature rises to 80° and fan turns on. Once it cools to 65° the fan will shut off. If evening comes and temp does not fall below 65° to reset the switch, then the unit will start the next morning at sunrise and continue to cool the hen house. However, if the room temp falls below 65° at night, then the switch will shut off and will not turn the unit on again until room temp reaches 80°.