A heat exchanger system for extracting heat from a process fluid comprising: a process fluid inlet; a process fluid outlet; a dry indirect contact heat exchange section receiving process fluid from the process fluid inlet and having an air inlet side, an air outlet side and a process fluid inlet and a process fluid outlet; an evaporative indirect contact heat exchanger section that is split into at least two process fluid flow paths, a process fluid inlet and a process fluid outlet for each of the two process fluid flow paths, and an air inlet side and an air outlet side; a respective sub-section (5, 7) provided for each path; an air moving system for moving air through the heat exchangers that can be induced draft, forced draft or other, a distribution system for selectively distributing an evaporative liquid to the evaporative indirect contact heat exchanger section; a process fluid connecting flow path from the dry indirect contact heat exchange section, which then connects to a first respective evaporative indirect heat exchange sub-section; characterised in that, a mechanism for directing the process fluid selectively to the process fluid inlets of the evaporative indirect contact heat exchanger sections such that all of the process fluid first enters the first evaporative sub-section and then may be entirely directed through a second sub-section, may be entirely directed out of the evaporative indirect contact heat exchanger section through a first evaporative sub-section outlet; or may be split evenly or unevenly between second sub-section and the first evaporative sub-section outlet; and a process fluid outlet flow path from the second indirect heat exchanger sub-section to the process fluid outlet. a process fluid inlet; a process fluid outlet; a dry indirect contact heat exchange section receiving process fluid from the process fluid inlet and having an air inlet side, an air outlet side and a process fluid inlet and a process fluid outlet; an evaporative indirect contact heat exchanger section that is split into at least two process fluid flow paths, a process fluid inlet and a process fluid outlet for each of the two process fluid flow paths, and an air inlet side and an air outlet side; a respective sub-section (5, 7) provided for each path; an air moving system for moving air through the heat exchangers that can be induced draft, forced draft or other, a distribution system for selectively distributing an evaporative liquid to the evaporative indirect contact heat exchanger section; a process fluid connecting flow path from the dry indirect contact heat exchange section, which then connects to a first respective evaporative indirect heat exchange sub-section; characterised in that, a mechanism for directing the process fluid selectively to the process fluid inlets of the evaporative indirect contact heat exchanger sections such that all of the process fluid first enters the first evaporative sub-section and then may be entirely directed through a second sub-section, may be entirely directed out of the evaporative indirect contact heat exchanger section through a first evaporative sub-section outlet; or may be split evenly or unevenly between second sub-section and the first evaporative sub-section outlet; and a process fluid outlet flow path from the second indirect heat exchanger sub-section to the process fluid outlet.