Good morning,

I'm molding an existing outpatient facility and I've ran into an issue.

One of the HVAC units is a packaged DX unit supplying a few surgical rooms. The HVAC was designed around a class A or less operating room way back at the time of the original install. They've since changed to class C operating rooms which have more strict airflow requirements. The building owners decided to modify the existing system rather than replace with new.

That being said, the unit is still a DX cooled unit with in-duct steam humidification and HW reheat at the zone level. There is electric backup heat in the unit if the boilers fail.

Here's the issue....

The surgeons requested the rooms maintain 60 degrees all year round. The existing unit couldn't maintain temperature. Therefore, there has been an air cooled packaged chiller added with a chilled water coil attached to the outdoor air intake to cool and dehumidify the outdoor air before entering the unit.

I cannot find a way to model DX and chilled water at the same time. Does anyone have any suggestions?

Thanks in advance!