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[EnergyPlus_Support] Re: Zone will not reach setpoint
I'll try it!
FYI, ... back earlier in May I posted a problem (Forum message 11377)
noting that I had non-zero loads in the zones, but the system was
calculated to have zero flow / load. That file was uploaded and
called something like "Non-zero loads". Fred Buhl worked on it and
recommended that I change (guess what?) the "central heating design
supply temp" from 12.8C to the value it's now at. I sent him an
e-mail on 5/27 asking about it, but haven't heard back. Fred has the
"non-zero" file (so do I), but I deleted it from the Forum upload area.
In short, your fix counters an earlier fix. There may be other factors
which I've inadvertantly altered since the original problem, but I
want you to be aware of the history....
Also, regarding your last message about using a higher discharge
setting in the wimter: Good call! That will be one of the savings
strategies employed for the real building model. This model is a
"Baseline" for an ASHRAE 90.1 analysis, so I am using the
ASHRAE-specified HVAC and controls (which do not call for winter reset
of discharge temp)
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
<RRaustad@...> wrote:
>
> You might also consider using the main air loop heating coil to pick up
> more of the load. Why did you choose to heat the air to 12.8C in the
> main air loop during the winter design day?
>
> Richard Raustad wrote:
> >
> > Change your "Central heating design supply air temperature (C)" to
match
> > what is entering the zone terminal unit heating coil. In this case
it is
> > 12.78 C. The zone now maintains 18-20C.
> >
> > SYSTEM SIZING,
> > AirLoop_AH1, !- name of an AIR PRIMARY LOOP object
> > sensible, !- type of load to size on
> > Autosize, !- Design (minimum) outside air volumetric
> > flow rate {m3/s}
> > 1, !- minimum system air flow ratio
> > 4.44, !- Preheat design temperature {C}
> > 0, !- Preheat design humidity ratio
> > {kg-H2O/kg-air}
> > 12.78, !- Precool design temperature {C}
> > 0.0087, !- Precool design humidity ratio
> > {kg-H2O/kg-air}
> > 12.78, !- Central cooling design supply air
> > temperature {C}
> > 12.78, !- Central heating design supply air
> > temperature {C} <--------
> > coincident, !- Sizing Option
> > no, !- Cooling 100% Outside Air
> > no, !- Heating 100% Outside Air
> > 0.0087, !- Central cooling design supply air
> > humidity ratio {kg-H2O/kg-air}
> > 0, !- Central heating design supply air
> > humidity ratio {kg-H2O/kg-air}
> > design day, !- cooling design air flow method
> > , !- cooling design air flow rate {m3/s}
> > design day, !- heating design air flow method
> > ; !- heating design air flow rate {m3/s}
> >
> > JV Dirkes II wrote:
> > >
> > > Dear E+ Forum,
> > >
> > > I've tried using V2.2.026, since that version addresses a known
reheat
> > > problem, but the model still reflects the problems noted in my last
> > post.
> > >
> > > Can anyone help?
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "JV Dirkes II"
> > <jvd2pe@>
> > > wrote:
> > > >
> > > > Dear E+ Forum,
> > > >
> > > > I am still hoping for some help with this problem. I've added
report
> > > > variables, tried different settings, double and triple checked
all th
> > > > input, and still cannot get the zone to warm up.
> > > >
> > > > Thanks in advance.
> > > >
> > > > p.s., The uploaded file is called "ZoneTooCold.zip"
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "JV Dirkes II"
<jvd2pe@>
> > > > wrote:
> > > > >
> > > > > Dear E+ Forum,
> > > > >
> > > > > My current model includes a variable volume air handler and VAV
> > boxes
> > > > > with reheat coils. The zone which represent 90% of the building
> > never
> > > > > reaches its setpoint on the Winter Design Day.
> > > > >
> > > > > Per report variables, the air handler has proper temperature
heating
> > > > > hot water (82C) and the discharge temperature is at the expected
> > > > > setpoint (12.9C). Air flow is autosized.
> > > > >
> > > > > The zone reheat coil is also autosized and has the same
heating hot
> > > > > water temperature as the air handler. Per report variables, the
> > > > > reheat coil has water flow and is using energy, but only
heats the
> > > > > zone to 5C instead of the setpoint (21.1C).
> > > > >
> > > > > I've tried manually sizing the reheat coils much larger than
the
> > load,
> > > > > but they continue to use only a small fraction of their
capacity and
> > > > > the zone stays too cold. Please let me know what might
prevent the
> > > > > reheat coils from warming the zone properly. Thanks!
> > > > >
> > > > > p.s., I've uploaded the file in case it will be helpful.
> > > > >
> > > >
> > >
> > >
> >
> > --
> > 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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