SCHOFIELD, Wisconsin — Greenheck’s Model DGX and Model MSX make-up air units with packaged direct expansion (PDX) have increased their cooling and airflow options in housing size H22. When configured with PDX, these units now offer airflow up to 9,000 cfm and have added cooling capacities at 7, 10, and 16 tons, expanding their range for make-up air applications. Both units use environmentally friendly, EPA-compliant R-454B refrigerant for PDX cooling, with chilled water and evaporative cooling as alternatives. The redesigned Model DGX with PDX provides direct gas-fired heat up to 1,200,000 Btu/h and incorporates microchannel coils, which are smaller, use less refrigerant, and transfer heat more efficiently. Model MSX is available with electric heat, steam coils, or hot water coils.