In the January 2003 report, we reviewed different options for locating a free cooling heat exchanger within a central plant. You may recall that the tower side of the cooling tower bypass control valve seemed to make the most sense because it essentially allows for dual condenser water temperature control.
When in the free cooling mode, the towers operate to maintain cold water to the heat exchanger with the bypass valve closed. As a result, there is no circulation on the chiller side of the valve and the water temperature stays at room temperature. A chiller can then be started without delay when changing back to mechanical cooling.