[Equest-users] Difference btw no fan schedule and fan schedule set to 0

[Chris Hadlock]

Hell all,

I have a residential building where each suite has a PSZ (constant volume)
system (hot water heating from boiler, DX cooling). I'm trying to
understand the difference as far as eQuest is concerned between specifying *a
fan schedule whose values are set to 0* (i.e. OFF for all hours) and *not
specifying any fan schedule* (i.e. undefined). In both cases, I've set the
indoor fan mode to *Intermittent* and I've set the Night Cycle control
to *Cycle
On Any*.

For the most part, it doesn't change the heating, cooling, or fan power
that much (about 10%) but it does significantly change the number of hours
my fans are running as well as the hourly profiles (airflow, as well as
heating and cooling load profiles). Evaluating one residential unit for
comparison purposes, I've noticed that running with a zero fan schedule
reduces the fan hours by about half compared to running with no assigned
schedule.

The graph below is what I get when I don't specify any fan schedule
(undefined). You will note  the airflows go from very small values (less
than 100 cfm) to a max of 675 cfm.
[image: image.png]

The graph below is what I get when I specify a fan schedule whose values
are set to 0. You will note the airflows range from a min of 225 cfm to 700
cfm. If you remove the hours with less than 225 cfm from the above graph,
you more or less end up with the below graph.
[image: image.png]

Is anybody able to explain why eQuest treats these two different fan
control scenarios differently...ultimately I'm trying to understand which
is more accurate from a real life perspective.

Thanks,
Chris
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