[Equest-users] Packaged RTU w/ Precool Chiller

[Sharad Kumar via Equest-users]

Hi Tom,


You can model the aircooled chiller system as a separate system serving the
treated outside air to various zones or system.

This can be done by making a system supplying to a dummy zone then the
system serving the OA to various systems.

The supposed to be linked system comes in the outside air tab in air-side
system.

To maintain the set-point you need to have design set-point below 60 degree.

In the model you need to have a design cooling set-point less than 60
degree for all the systems and then take help of SS-D report to have a look
how the zone temperature is meeting the set-point.

For having the general system you can take packaged single zone and take
hot water loop at the zone level (or system level).


*Thanks,*

Sharad.Kumar


------------------------------ Forwarded message
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From: Tom Mickley via Equest-users <equest-users at lists.onebuilding.org>
To: "equest-users at onebuilding.org" <equest-users at onebuilding.org>
Cc:
Date: Thu, 22 Dec 2016 14:22:57 +0000
Subject: [Equest-users] Packaged RTU w/ Precool Chiller

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!
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