Thermal energy system and method for its operation

A method for operating a thermal energy system, the thermal energy system comprising at least two exchanger modules, each exchange module including at least one heat exchanger, at least a first circuit for a first fluid traversing, in a regular mode of operation, through the heat exchanger in a main flow direction, a second circuit for a second fluid for exchanging thermal energy between the first fluid and the second fluid, and at least one pump including a fluid drive device for driving the first fluid in the main flow direction, characterised in that the drive device is arranged, along the main flow direction, upstream of the heat exchanger, wherein

• the system is adapted to connect in series, in a cleaning mode, the first circuits of at least two exchanger modules in a manner such that the first fluid traverses through at least a first circuit of one of the exchanger modules in the main flow direction and traverses through at least a first circuit of another exchanger module in a direction opposite to the main flow direction, the method including the following steps:
• the driving, along the main flow direction, of the first fluid present upstream of the heat exchanger by the drive device;
• and
• the activation of a cleaning mode in which the first circuits of at least two exchanger modules are connected in series in a manner such that the first fluid traverses through at least a first circuit of one of the exchanger modules in the main flow direction and traverses through at least a first circuit of another exchanger module in a direction opposite to the main flow direction.