A gas compressing system includes a compressor that provides a flow of compressed gas, a first desiccant tower, and a second desiccant tower separate from the first tower. The system also includes a first separator, a second separator separate from the first separator, an outlet, a first set and second set of no more than three valves each movable between an open position and a closed position. The flow flows along a flow path from the compressor to the first tower, to the first separator, to the second tower and out the outlet when the first set of valves is open and the second set of valves is closed. The flow of compressed gas flows from the compressor to the second tower, to the second separator, to the first tower and out the outlet when the first set of valves is closed and the second set of valves is opened.