Greenheck’s DGX and MSX makeup-air units now can be configured with a direct-drive, backward-curved plenum supply fan. Both models offer an operating range capable of 800 to 25,000 cfm and external static pressure of up to 4 in. wg. DGX-P and MSX-P offer additional design solutions when an application requires higher external static pressures caused by extensive ductwork or higher-efficiency filtration. The factory-mounted variable-frequency drive provides an inherent soft-start for the supply fan, while the absence of belts and sheaves reduces maintenance and simplifies air balancing in the field. Available heating options include direct gas-fired, electric-heat, hot-water, and steam coils; cooling options include split direct expansion, chilled water, and evaporative cooling. The new backward-curved plenum supply fan can lead to lower motor horsepower and energy use compared with other fan options.