Hello All,

This is a repost with a hopefully better explanation of the system that we
are trying to model. We have a campus project with a unique HVAC system for
cooling that reuses return water from a central plant that has already
circulated to other campus buildings. Outside air is taken in and cooled
first through an energy recovery wheel (using building exhaust), then sent
through a pre-cool coil that uses 55?F return water from the central plant
return loop to cool the air from 105F to 65?F. This air is sent through a DX
cooling coil of a water source heat pump and further cooled to 48?F and then
mixed with return air that has been cooled to 58?F also using a portion of
the 55?F return water from the central plant. The water leaving both the
return air and outside air pre-cooling water coils is used for heat
rejection of the water source heat pump, which returns 75F water to the
central plant. We are at a loss as to how to model this system, if it is
even possible. If anyone has seen a system like this, your help would be
greatly appreciated.

Thanks!

Jason Cocek, LEED AP O+M