The Dewpoint Plus is an energy saving system that allows the user to program a controller for the desired dew point. This system regenerates the "off-line" vessel completely and allows that vessel to remain idle, while the "on-line" vessel dries service air. Outlet air flow is continously sampled and once the desired dewpoint is reached a "tank-switchover" occurs and a new cycle begins. This option saves a significant amount of "purge air" each year thereby providing energy savings. This option includes a programmable digital display, and extremely accurate sensor and a high humidity alarm.