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[EnergyPlus_Support] Re: Cooling set-point not fully achieved
Is this problem equally likely to happen if I use a Purchased Air
approach?
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
<RRaustad@...> wrote:
>
> 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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