Abstract: A regenerative air drying system including at least one dryer module including a housing having a inlet air passage, an outlet air passage, and a wash air passage. The air dryer system further includes a desiccant canister mounted to the housing and in communication with the inlet, outlet, and exhaust air passages, and a single controllable valve selectively moveable between a first position and a second position, wherein the single controllable valve, when in the first position, forms a supply air flow path from the inlet air passage, through the desiccant canister in a first direction, and to the outlet air passage, and when in the second position, forms a wash air path from the outlet air passage, through the desiccant canister in a direction opposite the first direction, and to the exhaust air passage.