Water heater comes from the manufacturer set at 120 . We get lots of calls about running out of hot water with temp set that low. Although 120 is safer , 120 will not hold up to multiple back to back uses with out running out of hot water. Every residental water heater we install we set them to 130-135 unless the owner wants them set lower. When winter comes the ground water is much colder 120 will be even harder to keep up especially with back to back uses.