Hello all,

Does anyone have any idea how I would model this hybrid HVAC system that I
have. I will attempt to explain it as best as I can. If anyone has any
ideas about how I could model this, I would greatly appreciate the help. The
project is on a college campus with a central plant. For cooling, the system
is reusing return water from the central plant that has already circulated
to other buildings on the campus loop. Outside air is taken in and cooled
first through a heat exchanger, then sent through a pre-cool economizer that
uses 55? return water from the central plant to cool the air to 65?. This
air is sent through a DX cooling coil and further cooled to 48? and then
mixed with return air that has been cooled to 58? also reusing return water
from the central plant. All water from the system goes through a
water-cooled DX compressor before it is returned back to the central plant.
I need to figure out how to best model this in eQuest to account for the
reuse of the return water if this is even possible. The only way we could
think to model it would be to model a water source heat pump on the cooling
side and the district loop on the heating side, but this does not account
for the reuse of the return water. If anyone has any thoughts, I would
really appreciate it.

Thanks,

Jason Cocek, LEED AP O+M