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Re: [EnergyPlus_Support] Re: Fwd: Warning: Maximum iterations exceeded
The HVAC iteration error is reported at the system time step. This time
step can be much shorter than the zone time step's 15-minute interval
you have specified (in fact the HVAC time step can be reduced down to
1-minute time steps). In addition, the simulation iterates multiple
times. So you are not seeing 40%, it's probably less than 10%. Look at
the times in the warnings, does the same time show up more than once? I
have always thought that these warnings were related to plant loops. Do
you have chilled water, condenser, or hot water loops in your
simulation? Do these loops, or the air loop for that matter, meet the
set points (not the zone temperature set point, the node set points if
your using Set Point Managers )?
anarui.oliveira wrote:
>
> I didn't worry too much, at first, because the temperature control is
> actually pretty good.
> The thing that got me worried is that the warnings are pretty
> repetitive (estimating nº of warnings over nº of predefined time
> steps, 4 per hour, about 40% have warnings).
>
> Thanks,
> Ana.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > I'm not so sure smoothing schedules will help to any degree. You
> may
> > have been reading a post with regard to the zone temperature being
> > slightly lower than the zone temperature set point. I think you
> should
> > look at how the zone temperatures are controlled with respect to
> the
> > zone temperature set point. Even when the maximum iteration limit
> is
> > exceeded, the error in the predicted energy use can be very small.
> > Checking your results should always be the final step in any
> simulation.
> >
> > anarui.oliveira wrote:
> > >
> > > I have browsed through old messages mentioning this topic, and
> got the
> > > idea that maybe the fact that internal gains' schedules change
> quite
> > > abruptly can contribute to this problem?
> > > If I "smooth" this schedules (by detailing, in smaller intervals,
> the
> > > equivalent linear variations of the original hourly schedules),
> could
> > > it help?
> > >
> > > In any case, when I get these warnings, how can it affect the
> energy
> > > loads estimates?
> > >
> > > Thanks again for any help,
> > >
> > > Ana.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "anarui.oliveira"
> > > <anarui.oliveira@> wrote:
> > >
> > > Any hints about the possible causes and effects of the Maximum
> > > iterations warnings?
> > >
> > > ** Warning ** SimHVAC: Maximum iterations (20) exceeded for all
> HVAC
> > > loops, at Leiria PRT INETI data WMO#=085360, 08/01 10:15 - 10:30
> > >
> > > ** Warning ** SimHVAC: Exceeding Maximum iterations for all HVAC
> > > loops, during Leiria PRT INETI data WMO#=085360 continues
> > >
> > > Thanks in advance,
> > > Ana Rui.
> > >
> > > --- End forwarded message ---
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu
UCF - From Promise to Prominence: Celebrating 40 Years
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