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Re: [EnergyPlus_Support] Re: Cooling set-point not fully achieved



You could try increasing the time step in hour. I have no other 
suggestions. This is a known issue and we are working to correct it.

anarui.oliveira wrote:
>
> That field is already set to 1, and time step in hours is set to 4.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > What you describe is not a capacity issue, it is related to the
> > prediction of loads. If you add the report variable for "Zone/Sys
> > Sensible Load Predicted" and set the report variable frequency to
> > detailed, you will see why this is happening. Try reducing the
> Minimum
> > System Time Step in the System Convergence Limits object. You
> probably
> > will not eliminate the problem, but it should get better.
> >
> >
> > anarui.oliveira wrote:
> > >
> > > What if, in a similar (heating) case, water flow doesn't reach the
> > > maximum when the problem occurs, and increasing the air flow
> causes
> > > further departure from temperature setpoint?...(Less than about
> 1.5
> > > times the auto-sized air flow also leads to poorer setpoint
> > > tracking); reported air flow is always equal to the constant
> volume
> > > fan flow, and ouside air flow rate is (and must be) user
> specified.
> > >
> > > Regards,
> > > Ana.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > <RRaustad@> wrote:
> > > >
> > > > Then try again to manually size the coil in the problem zone to
> > > twice
> > > > the size reported in the eio file. Also increase the air flow
> rate
> > > for
> > > > that fan coil unit and fan to twice the autosized value. If
> htis is
> > > > happening in more than 1 zone, then just pick 1 for now to test
> > > this out.
> > > >
> > > > Then tell me what happens to the maximum zone temperature. Did
> the
> > > > maximum zone temperature go down? Also tell me if the water flow
> > > rate is
> > > > at a maximum when the zone temperature exceeds the set point.
> You
> > > can
> > > > report "System Node VolFlowRate" for the coil water inlet node
> and
> > > fan
> > > > coil air inlet node to easily match volumetric flow rate with
> your
> > > inputs.
> > > >
> > > > This just sounds like a sizing issue and should be easily
> resolved.
> > > >
> > > > anarui.oliveira wrote:
> > > > >
> > > > > Apparently, yes, but I set it to autosize (and I think I
> already
> > > did
> > > > > a trial with a larger, user-defined, water flow rate)...
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > > > <RRaustad@> wrote:
> > > > > >
> > > > > > I have not looked at your input file, can you tell me if the
> > > water
> > > > > mass
> > > > > > flow rate through the fan coil is at a maximum when the
> cooling
> > > set
> > > > > > point is not met?
> > > > > >
> > > > > > anarui.oliveira wrote:
> > > > > > >
> > > > > > > Please forgive me for insisting, but I DO have some
> urgency on
> > > > > this
> > > > > > > one...
> > > > > > > Again, thanks for any help,
> > > > > > > Ana.
> > > > > > >
> > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > <mailto:EnergyPlus_Support%
> > > 40yahoogroups.com>, "anarui.oliveira"
> > > > > > > <anarui.oliveira@> wrote:
> > > > > > > >
> > > > > > > > Hi again.
> > > > > > > >
> > > > > > > > I'm uploading a new file (Zone36598_cFancoil_exp),
> hoping
> > > that
> > > > > > > someone
> > > > > > > > can help me figure out why the cooling setpoints are not
> > > being
> > > > > > > achieved
> > > > > > > > for all times when the controls are active (namely in
> Zone
> > > > > 36598).
> > > > > > > The
> > > > > > > > model consists of Fancoil units created with Compact
> HVAC,
> > > and
> > > > > then
> > > > > > > > edited in the expanded file.
> > > > > > > > I tried several user-defined and sizing options, but
> > > couldn't
> > > > > solve
> > > > > > > the
> > > > > > > > temperature peaks above 25ºC.
> > > > > > > >
> > > > > > > > Thanks in advance,
> > > > > > > > Ana Rui.
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > > --
> > > > > > 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>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <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 
> <http://www.fsec.ucf.edu>
> <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 <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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