I'm modeling a hotel with ERUs that provide OA directly to each guest room
(at neutral conditions) in which a PTAC conditions and recirculates the air
at the design temperatures (72/75). I have the ERUs providing OA to a dummy
zone without internal loads at different temperatures (76/89). My question
is when the ERU is exhausting, how can I tell it to exhaust the conditioned
air from the guest rooms instead of the OA that it is directly supplying to
the dummy zone? My ERU should technically be exhausting air around 76deg F,
but I have a feeling that it would just be exhausting the same temperature
air that it is supplying to the dummy zone.

I'm also seeing a larger than expected summer heating load on these units,
which may or may not be caused by my question above.

Any help would be much appreciated.

Tracie Monfort