Dedicated outdoor air systems, DOAS, are used to provide ventilation and dehumidification for spaces that use additional equipment to cool and heat the space. Often this sensible cooling equipment does not have drain pans and good control is required for the system including the DOAS. Exhaust air energy recovery is often applied in the DOAS to precool during the summer and preheat during the winter. The primary purpose of the DOAS is to provide ventilation air to the occupants and dehumidify the building during the cooling season. Most of the cooling is accomplished by the terminal equipment in the space. This zone control often leads into using another sensible exchanger to recover heat from the exhaust to prevent over cooling of the DOAS air. Thus, the DOAS has two exchangers that are used in conjunction with a cooling coil during dehumidification hours. During heating both of these may or may not be used with an ancillary heating coil. This paper will go detail the control and function of the DOAS and the exhaust air recovery exchangers during various modes of operation and how to reduce the energy required to dehumidify and heat the ventilation air.