100% OA unit with DCV shows return air flow.

asked 2022-08-19 18:01:22 -0600

aleexga's avatar

Hi all, I am trying to model a 100% outside air unit with DCV. The air loop is set up with energy recovery and a cooling coil. I have everything I believe I need for the unit to be 100% outside air, however, when looking at the volume flow rate for before and after the controller, the airflow is not equal. The ariflow before the controller is showing DCV, the airflow after the controller shows an on/off, showing that the DOAS is returning some airflow and is not 100% outside air.

What am I missing here for it to be 100% outside air? (Refer to DOAS 2)

A few additional notes: @ the loop Sizing:system, -I have 100% outside air in heating and cooling -My system outdoor air method is set to zone sum -My type of load to size is ventilation requirement

@ the controller, -I don't have any schedules for min outdoor air and/or fraction.

@ the terminals, -Control for outdoor air is set to Yes -Minimum air flow fraction schedule is set to Always On.

@ the zone: - Account for dedicated outdoor air system is set to Yes -Dedicated outdoor air system strategy is set to neutral supply air.

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