A chiller system comprising: a chiller (1, 1_1, 1_2, 1_3) configured to output water at an adjusted temperature; a load of the chiller (1, 1_1, 1_2, 1_3); a feed pipe (3, 3_1, 3_2, 3_3, 8) through which water flows to be supplied from the chiller (1, 1_1, 1_2, 1_3) to the load, the feed pipe (3, 3_1, 3_2, 3_3, 8) being connected between the chiller (1, 1_1, 1_2, 1_3) and the load; a return pipe (4, 4_1, 4_2, 4_3, 9) through which water flows back to the chiller (1, 1_1, 1_2, 1_3) from the load, the return pipe (4, 4_1, 4_2, 4_3, 9) being connected between the chiller (1, 1_1, 1_2, 1_3) and the load; a first controller (C, C_1, C_2, C_3) configured to control the chiller (1, 1_1, 1_2, 1_3); and a second controller configured to output a chiller operating command to control the chiller (1, 1_1, 1_2, 1_3) to the first controller (C, C_1, C_2, C_3), wherein the chiller (1, 1_1, 1_2, 1_3) includes a first sensor (IS, IS_1, IS_2, IS_3) configured to measure an inlet water temperature of the water flowing through the return pipe (4, 4_1, 4_2, 4_3, 9) to the chiller (1, 1_1, 1_2, 1_3), a second sensor (OS, OS_1, OS_2, OS_3) configured to measure an outlet water temperature of the water flowing through the feed pipe (3, 3_1, 3_2, 3_3, 8) from the chiller (1, 1_1, 1_2, 1_3), and a third sensor (S, S_1, S_2, S_3) configured to measure an outside air temperature at a location where the chiller (1, 1_1, 1_2, 1_3) is installed, and characterized in that the first controller (C, C_1, C_2, C_3) is configured to calculate a temperature range that is operational for the chiller (1, 1_1, 1_2, 1_3) based on an inlet water temperature measured by the first sensor (IS, IS_1, IS_2, IS_3), an outlet water temperature measured by the second sensor (OS, OS_1, OS_2, OS_3), and an outside air temperature measured by the third sensor (S, S_1, S_2, S_3), and then output information on the calculated temperature range to the second controller. a chiller (1, 1_1, 1_2, 1_3) configured to output water at an adjusted temperature; a load of the chiller (1, 1_1, 1_2, 1_3); a feed pipe (3, 3_1, 3_2, 3_3, 8) through which water flows to be supplied from the chiller (1, 1_1, 1_2, 1_3) to the load, the feed pipe (3, 3_1, 3_2, 3_3, 8) being connected between the chiller (1, 1_1, 1_2, 1_3) and the load; a return pipe (4, 4_1, 4_2, 4_3, 9) through which water flows back to the chiller (1, 1_1, 1_2, 1_3) from the load, the return pipe (4, 4_1, 4_2, 4_3, 9) being connected between the chiller (1, 1_1, 1_2, 1_3) and the load; a first controller (C, C_1, C_2, C_3) configured to control the chiller (1, 1_1, 1_2, 1_3); and a second controller configured to output a chiller operating command to control the chiller (1, 1_1, 1_2, 1_3) to the first controller (C, C_1, C_2, C_3), wherein the chiller (1, 1_1, 1_2, 1_3) includes a first sensor (IS, IS_1, IS_2, IS_3) configured to measure an inlet water temperature of the water flowing through the return pipe (4, 4_1, 4_2, 4_3, 9) to the chiller (1, 1_1, 1_2, 1_3), a second sensor (OS, OS_1, OS_2, OS_3) configured to measure an outlet water temperature of the water flowing through the feed pipe (3, 3_1, 3_2, 3_3, 8) from the chiller (1, 1_1, 1_2, 1_3), and a third sensor (S, S_1, S_2, S_3) configured to measure an outside air temperature at a location where the chiller (1, 1_1, 1_2, 1_3) is installed, and characterized in that the first controller (C, C_1, C_2, C_3) is configured to calculate a temperature range that is operational for the chiller (1, 1_1, 1_2, 1_3) based on an inlet water temperature measured by the first sensor (IS, IS_1, IS_2, IS_3), an outlet water temperature measured by the second sensor (OS, OS_1, OS_2, OS_3), and an outside air temperature measured by the third sensor (S, S_1, S_2, S_3), and then output information on the calculated temperature range to the second controller.