Dedicated Outdoor Air Systems (DOAS) are units that supply 100% outdoor air. The main point behind these systems is to provide dedicated ventilation rather than ventilation as an incidental part of the process of conditioning interior air. These units may have any combination of heating coil, cooling coil, and heat recovery. They may also have de-humidification and humidification controls as well as several supply temperature control types. The Default Air System Templates include several variations of DOAS that can be used on projects.
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To force any Air System to operation in 100% OA operation, all you need to do is set the Economizer Parameters inputs Minimum Outside Air Fraction and Maximum Outside Air Fraction to Always On schedules.
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These inputs determine the schedule for outdoor airflow into the central system, so enabling them to be always on effectively converts it into a 100% outdoor air system. Additional central or zone components may then be added as necessary to further customize the system.