The present disclosure relates to a gradient coil system (107, 207) for a magnetic resonance imaging, MRI, system (100). The gradient coil system (107, 207) comprises: a plurality of gradient coils (110A-C, 210A-C) for applying a gradient magnetic field to a target volume (108); at least one coolant tube (120A-C, 220A-C, 320A-C) per gradient coil (110A-C, 210A-C) for cooling the gradient coil (110A-C, 210A-C), the coolant tubes (120A-C, 220A-C, 320A-C) being connected to respective flow control devices (122A-C, 222A-C, 322A-C); a controller (124, 224, 324) coupled to the coolant tubes (120A-C,220A-C, 320A-C) configured to control each flow control device of the flow control devices (122A-C, 222A-C, 322A-C) for adjusting the flow of a coolant in the respective coolant tube (120A-C, 220A-C,320A-C), wherein the controller (124, 224, 324) is configured to control the flow control device (122A-C, 222A-C, 322A-C) on the basis of heat load caused by the respective gradient coil (110A-C, 210A-C).