VRF Outdoor Air Autosizing Problem

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@kwalkerman But AirTerminal:SingleDuct:Mixer is different from VAVBox with NoReheat, correct ? Does this rule apply to VAVBox wtih NoReheat as well ?

And also, in actual operation, the VRF terminal do receive OA from the DOAS system. If it is set zero, the VRF will have no OA in cooling or heating condition which is not true in reality. (I ran two models and compared)

AirTerminal:SingleDuct:Mixer is a special type of air terminal that allows you to provide air to a ZoneHVAC:Equipment object, instead of providing air directly to the zone. The other flavors of AirTerminal:SingleDuct only provide air directly to the zone.

There are two ways to set up the mixer. In my experience, the method that is applied in real buildings is that pictured above, with the mixer supplying outdoor air mixed with zone air to the supply side of the terminal unit. The mixer receives air from an airloop (usually outdoor air) and mixes it with the return air from the zone.

.. continued from above

If you look at the node connections between the two objects, I think it'll make more sense. Without a DOAS, the VRF terminal unit will receive outdoor air directly from it's own outdoor air mixer. In this case, if you looked at hourly variables, you'll see an airflow at the outdoor air inlet node. With a DOAS, the outdoor air is mixed in prior to the VRF inlet node, so you'd need to look for the outdoor air farther upstream.