Free Cooling - Strainer Cycle

Like other methods of free cooling, the addition of a strainer-cycle waterside economizer is intended to reduce water chiller energy consumption. This particular method uses cooling tower water to satisfy the building's cooling load. Whenever ambient wet bulb temperature is low enough, cooling tower water is "valved" around the chiller directly into the chilled water loop. The cooling tower water typically passes through a filter (or strainer) before entering the chilled water circuit. This is why it is commonly referred to as "strainer cycle."

Pumping cooling tower water throughout the entire chilled water loop increases the risk of pipe corrosion and air handler coil plugging. This risk can be mitigated through more costly water treatment.

Strainer cycle economics are limited since free cooling is only available when the cooling load can be satisfied with cooling tower water. The cooling tower must be designed for winter operation.