[EnergyPlus_Support] Re: Setpoint not met during night cycle

["JV Dirkes II" <jvd2pe@xxxxxxx>]

Dear E+ Forum,

After experimenting some more, it appears that the SYSTEM AVAILABILITY
MANAGER:NIGHT CYCLE "Cycling run time" was preventing the zone from
reaching the setpoint.  When I set it for 900s (15 min), it would turn
the system OFF at the end of that period, even though the setpoint was
not met. In other words, it came ON for 900s, turned OFF for 900S,
then ON for 900s , etc.

When I set the "Cycling run time" for 3600s, it operates on a longer
cycle, which allows the zone to warm properly.  Of course the fan runs
a lot more, too!

I guess I've solved my own problem for now, but still have a question:

1) Is the SYSTEM AVAILABILITY MANAGER:NIGHT CYCLE supposed to work
this way?  It seems to me that a control system should operate in
NIGHT CYCLE as long as needed to achieve the setpoint, and then shut
off.  My first understanding of the "Cycling run time" was as a
MINIMUM run time.  That's apparently incorrect, but it seems to be
more appropriate....

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "JV Dirkes II" <jvd2pe@...>
wrote:
>
> Dear EPlus Forum,
> 
> Please help me determine why my model maintains proper setpoints
> during Winter Design Days in the "night" period, but fails to do so on
> other winter days.
> 
> During the night, the setpoints are as expected, the system cycles on
> and off as expected (I'm using a SYSTEM AVAILABILITY MANAGER:NIGHT
> CYCLE), but the zone temp is much lower than the setpoint (including
> the thermostat on/off tolerance).
> 
> I'll upload the file....
>



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