DGX-22-OpenGreenheck make-up air Models DGX and MSX can be configured with direct drive, backward-curved plenum supply fan. Both models offer operating range capable of 800–25,000 cfm and external static pressure up to 4 in. wg. DGX-P and MSX-P offer additional features for when applications require higher external static pressures. Along with factory-mounted VFD that provides inherent soft-start for supply fan, features include multiple heating and cooling options.