Available on 2–6 ton horizontal and vertical Versatec Base, Versatec Ultra Envision2 Compact, and 7-25 ton horizontal and vertical Envision XL products, Waterside Economizer option allows use of building’s interior loop water to provide free cooling. Economizer works by passing air through internal coil cooled by loop water rather than by mechanical refrigeration. Unit contains water-to-air heat exchanger, 3-way valve, and controls that manage flow of water through heat exchanger.