[Equest-users] Variable Volume Help Needed!

[Matt Larson]

I am modeling a building with an existing single zone 4-pipe chilled and hot water air handler unit that is currently constant volume but being converted to constant volume.  The unit feeds many spaces through a single duct.  I modeled the system as a single zone with heat (SZRH) system and tried to add in a variable speed drive and lower the minimum flow ratio, but can't get the fan speed to reduce when not needing 100% flow.  I also tried modeling the system as a variable volume system (VAVS) and the airflow ramps down but then the program adds a VAV box for each zone, which isn't what is occurring.  I am trying to control only to the worst case zone, as will be the installed case.

Which system type should I be using for modeling this system, and how do I get it to model as noted above?

I appreciate any help!  Thanks,

Matt Larson, P.E., QCxP, LEED AP

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