Tower free cooling is a term used when a cooling tower is operated at low temperatures to produce chilled water when the outdoor conditions are suitable. The idea is to get chilled water without running chillers if outdoor temperatures are low enough. If tower free cooling is handled with an open evaporative cooling tower, then there should be a heat exchanger between the tower and the chilled water supply system so that the water condition in the closed chilled water circuit is not compromised.  If the cooling tower is a “closed circuit cooler”, then a heat exchanger is not likely to be present.