Greenheck makeup-air models DGX and MSX can now be configured with a direct-drive, backward-curved plenum supply fan. The 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 also 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. Company officials say the new backward-curved plenum supply fan can lead to lower motor horsepower and energy usage when compared to other fan options.