The Advanced Evaporator Unit uses a Variable-Speed Centrifugal Fan with Three Settings. The Settings include a "high" setting that allows for maximum performance, as well as a "low" setting for super-quiet operation. Please Note: The Evaporator Unit should be mounted close to the ceiling inside the cellar. The High Performance Condensing Unit is designed to handle environments ranging from 0°F to 110°F. The Condensing Unit requires 12 inches of unobstructed space in front of the coils, and requires approx. 600-700 CFM of ventilation when installed in a confined space. This CellarPro Split Wine Cellar Refrigeration System offers a choice of wiring. The Condensing Unit can be either electronically controlled and wired to the Evaporator (single power source on the Evaporator Side), or it can be controlled by a Solenoid Valve (dual power source, one each to the Evaporator and Condensing Unit). Please Note: the former choice (Electronic Wiring) will allow the Condensing Unit to be used in temperatures down to -20°F.