[EnergyPlus_Support] Ghost Fans?

["Kristin Field" <fieldkm@xxxxxxxxx>]

Hi, I'm having trouble with a residence I'm modeling in EP.  It has DX
cooling and furnace heating, with OA autosized and no economizer. 
Currently, heating is enabled all year, and cooling is only enabled
July-September.  Fans are enabled all year.  Natural ventilation is
also modeled in a ventilation object (not airflownetwork).  Controls
of cycfancyccoil and cycfancyccomp are used.

The problem is that, after reviewing the .csv with report variables of
fan consumption, cooling coil consumption, heating coil consumption,
and natural ventilation, I have found several timesteps where the fan
cycles on w/o either coil - and not just for one timestep, but for
several in a row.  The number of hours this happens is different in
the same model with and without natural ventilation.  I think this is
probably skewing my results as to the effect of natural ventilation on
consumption.  Even forgetting about the natural ventilation component,
I would think this would give me elevated fan energy results if the
fan isn't really supposed to cycle on like this.

Does anyone know why the fans would come on without a coil also coming
on, since there's no economizer?  From the documentation, I thought
coils and fans were supposed to cycle together (which I interpreted to
mean at the same times).

I will upload my .idf to the files section, along with a spreadsheet
that shows these fan, coil, and NV results that have puzzled me.

Help appreciated!

Thanks,
Kristin



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