Regenerative air dryers are disclosed for feeding pressurized air with a controlled moisture content to a header. In one embodiment, a dryer comprises first and second chambers alternating between drying and regenerating phases. One of the chambers is at the drying phase while the other is at the regenerating phase. A controller is programmed to switch the phase of the chambers between drying and regenerating when the desiccant in the chamber at the drying phase has retained water to a predetermined capacity. A bypass line bypasses both chambers. An input provides air to the chamber at the drying phase and to the bypass line. A dew point feedback system controls a volume of air passing through the bypass line. Means are included for combining air from the bypass line with air exiting the chamber at the drying phase to provide air with a controlled dew point to the header.