Re: [EnergyPlus_Support] Re: Help with override error

OKAY. the humidity and temperatures are about 18 degC and 70%RH at the zone equipment inlet node. The zone air node reports the realistic temperature with the unrealistic humidity. Could it be because of the Fan:ZoneExhaust objects that I have in the zone equipment, is somehow messing up the air balance?

My zone equipment looks like this:

ZoneHVAC:EquipmentConnections,
Underground:Basement, !- Zone Name
Underground:BasementEquipment, !- Zone Conditioning Equipment List Name
Underground:Basement Supply Inlet, !- List Name: Zone Air Inlet Nodes
Underground:Basement WC Exhaust Air Node, !- List Name: Zone Air Exhaust Nodes
Underground:Basement Zone Air Node, !- Zone Air Node Name
Underground:Basement Return Outlet; !- Zone Return Air Node Name

ZoneHVAC:EquipmentList,
Underground:BasementEquipment, !- Name
ZoneHVAC:AirDistributionUnit, !- Zone Equipment 1 Object Type
Underground:Basement ATU, !- Zone Equipment 1 Name
1, !- Zone Equipment 1 Cooling Sequence
1, !- Zone Equipment 1 Heating or No-Load Sequence
ZoneHVAC:LowTemperatureRadiant:VariableFlow, !- Zone Equipment 2 Object Type
Underground:Basement RF, !- Zone Equipment 2 Name
2, !- Zone Equipment 2 Cooling Sequence
2, !- Zone Equipment 2 Heating or No-Load Sequence
Fan:ZoneExhaust, !- Zone Equipment 3 Object Type
Underground:Basement XFan WC, !- Zone Equipment 3 Name
3, !- Zone Equipment 3 Cooling Sequence
3; !- Zone Equipment 3 Heating or No-Load Sequence

!!!!!!!!!!!!!!!Exhaust Fan WC Start

Fan:ZoneExhaust,
Underground:Basement XFan WC, !- Name WC Exhaust Fan
HVACTemplate-Always 1, !- Availability Schedule Name
0.7, !- Fan Efficiency
500, !- Pressure Rise {Pa}
28741, !- Mech ventilation (m3/s) 28741 mÂ³/h
Underground:Basement WC Exhaust Air Node, !- Air Inlet Node Name
Underground:Basement WC Outside Node, !- Air Outlet Node Name
WC Exhaust; !- End-Use Subcategory
!!!!!!!!!!!!!!!Exhaust Fan WC End

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
> This morning, I'm going to report more and more system nodes until I find where the RH drops (and I find it very unlikely that this is possible) from 80% (at cooling coil exit node) to 0.2% (in zone) (can one even dry air this much). I suspect a reporting error. Will keep posted what I find.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@> wrote:
> >
> > Hi, back again. Reported the coil air temperatures and humidities entering and leaving, and they seem to be in order. Still don't see where the zone relative humidities drop to fractions.
> >
> > The current problem submittal has following outputs (if you can think of any other interesting ones, pls let me know:
> >
> > Output:Variable, *,Plant Loop Cooling Demand,hourly;!HVAC,Average, [W]
> > Output:Variable,*, Zone Mean Air Temperature, hourly, On;
> > Output:Variable, *, Zone Air Relative Humidity, hourly, On;
> >
> >
> > Output:Variable,DOAS Mixed Air Outlet,System Node Temp,hourly;!HVAC,Average, [C]
> > Output:Variable,DOAS Cooling Coil Air Outlet,System Node Temp,hourly;!HVAC,Average, [C]
> > Output:Variable,DOAS Mixed Air Outlet,System Node Humidity Ratio,hourly;!HVAC,Average, [C]
> > Output:Variable,DOAS Cooling Coil Air Outlet,System Node Humidity Ratio,hourly;!HVAC,Average, [C]
> > Output:Variable,DOAS Mixed Air Outlet,System Node Relative Humidity,hourly;!HVAC,Average, [C]
> > Output:Variable,DOAS Cooling Coil Air Outlet,System Node Relative Humidity,hourly;!HVAC,Average, [C]
> >
> > ! OutputControl:Table:Style,
> > ! comma; !- Column Separator
> > ! Output:Table:SummaryReports,
> > ! AllSummary; !- Report 1 Name
> >
> > !Output:Surfaces:Drawing, DXF, Triangulate3DFace;
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@> wrote:
> > >
> > > Understood. I'll take a sharper look and get back to the thread later.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@> wrote:
> > > >
> > > > Does your input file include report variables for inlet air T and W, air
> > > > flow rate, coil cooling rate, etc. to use for debugging? Have you
> > > > checked the eio file for any indications of size of this coil? Being a
> > > > developer, I typically do not run files posted on the yahoo groups web
> > > > site since this is a peer-to-peer site.
> > > >
> > > > On 8/3/2011 9:50 AM, Jean marais wrote:
> > > > >
> > > > > Hi Richard,I now specified both and the error went away, but now I get
> > > > > garbage comming out with humidities of zero instead of close to 100%.
> > > > > I'm putting the 20110721.epmidf.zip in the problem files area.
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > > > <RRaustad@> wrote:
> > > > > >
> > > > > > This probably relates to your problem. You tell the program to chose
> > > > > the
> > > > > > inlet air humrat, but then specify the outlet air humrat.
> > > > > >
> > > > > > autosize, !- Design Inlet Air Humidity Ratio {kg-H2O/kg-air}
> > > > > > 0.0010, !- Design Outlet Air Humidity Ratio Entering is 0.01178 ,0.0050
> > > > > > does not work
> > > > > >
> > > > > > I would run the program for the sizing period and report the outdoor T
> > > > > > and W to see how these values change. That warning looks like one that
> > > > > > should provide more information. Alternately you could specify both or
> > > > > > autosize both.
> > > > > >
> > > > > > On 8/3/2011 8:52 AM, Jean marais wrote:
> > > > > > >
> > > > > > > Hi Richard,
> > > > > > >
> > > > > > > I've set the coil and it was working until I upped the entering
> > > > > > > humidity. I now get:
> > > > > > > ** Warning ** SizeWaterCoil: Coil="DOAS COOLING COIL", Cooling Coil
> > > > > > > has leaving humidity ratio > entering humidity ratio.
> > > > > > > ** ~~~ ** ..will be sized for 50% of entering humidity ratio.
> > > > > > >
> > > > > > > EVENTHOUGH entering air from outside has humidity of 0.01178 and the
> > > > > > > coil is set to 0.001.
> > > > > > >
> > > > > > > SizingPeriod:DesignDay, Summer Design Day in BBI Terminal, !- Design
> > > > > > > Day Name
> > > > > > > 32.0, !- Max Dry-Bulb {C}
> > > > > > > 10.3, !- Daily Temp Range {C}
> > > > > > > 0.01178,!21.74, !- Wet-Bulb at Max {C} gH2O/gDryAir
> > > > > > > 100761.7, !- Barometric Pressure {N/M**2}
> > > > > > > 0, !- Wind Speed {m/s}
> > > > > > > 0, !- Wind Direction {Degrees N=0, S=180}
> > > > > > > 0.98, !- Clearness {0.0 to 1.1}
> > > > > > > 0, !- Rain {0-no,1-yes}
> > > > > > > 0, !- Snow on ground {0-no,1-yes}
> > > > > > > 15, !- Day of Month
> > > > > > > 7, !- Month
> > > > > > > SummerDesignDay, !- Day Type -- used for schedules
> > > > > > > 1, !- Daylight Savings Time Indicator
> > > > > > > HumidityRatio,!WetBulb, !- Type of humidity temperature Indicator
> > > > > > > , !- Relative Humidity Day Schedule(not used)
> > > > > > > , !- Dry-Bulb Temperature Range Modifier Type (not used)
> > > > > > > ; !- Dry-Bulb Temperature Range Modifier Schedule (not used)
> > > > > > >
> > > > > > > Coil:Cooling:Water,
> > > > > > > DOAS Cooling Coil, !- Name
> > > > > > > 2, !- Availability Schedule Name
> > > > > > > autosize, !- Design Water Flow Rate of Coil {m3/s}
> > > > > > > autosize, !- Design Air Volume Flow Rate {m3/s}
> > > > > > > 6,!autosize, !- Design Inlet Water Temperature {C}
> > > > > > > 32,!autosize, !- Design Inlet Air Temperature {C}
> > > > > > > 18,!autosize, !- Design Outlet Air Temperature {C}
> > > > > > > autosize, !- Design Inlet Air Humidity Ratio {kg-H2O/kg-air}
> > > > > > > !autosize, !- Design Outlet Air Humidity Ratio {kg-H2O/kg-air}
> > > > > > > 0.0010, !- Design Outlet Air Humidity Ratio Entering is 0.01178
> > > > > > > ,0.0050 does not work
> > > > > > > DOAS Cooling Coil ChW Inlet, !- Coil Water Inlet Node
> > > > > > > DOAS Cooling Coil ChW Outlet, !- Coil Water Outlet Node
> > > > > > > DOAS Mixed Air Outlet, !- Air Inlet Node Name
> > > > > > > DOAS Cooling Coil Air Outlet, !- Air Outlet Node Name
> > > > > > > DetailedAnalysis, !- Type of Analysis
> > > > > > > CrossFlow; !- Heat Exchanger Configuration
> > > > > > >
> > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "Jean marais"
> > > > > > > <jeannieboef@> wrote:
> > > > > > > >
> > > > > > > > I have the following error:
> > > > > > > >
> > > > > > > > ************* Beginning System Sizing Calculations
> > > > > > > > ************* Beginning Plant Sizing Calculations
> > > > > > > > ** Warning ** In calculating the design coil UA for
> > > > > > > Coil:Cooling:Water DOAS COOLING COIL
> > > > > > > > ** ~~~ ** the apparatus dew-point is below the coil design inlet
> > > > > > > water temperature;
> > > > > > > > ** ~~~ ** the coil bypass factor is unrealistically large;
> > > > > > > > ** ~~~ ** the coil outlet design conditions will be changed to
> > > > > > > correct the problem.
> > > > > > > > ** ~~~ ** The initial design conditions are: Tair,in = 24.4500
> > > > > > > > ** ~~~ ** Wair,in = 9.478796E-003
> > > > > > > > ** ~~~ ** Twater,in = 6.0000
> > > > > > > > ** ~~~ ** Tair,out = 18.0000
> > > > > > > > ** ~~~ ** Wair,out = 8.000000E-003
> > > > > > > > ** ~~~ ** The revised design conditions are: Tair,out = 14.5987
> > > > > > > > ** ~~~ ** Wair,out = 9.371939E-003
> > > > > > > >
> > > > > > > > All my coil inputs possible are autosized. Zone and System humidity
> > > > > > > designs are 0.008 (default). My outlet Tair design is 18 deg (as seen
> > > > > > > in the error msg.)
> > > > > > > >
> > > > > > > > 1) What is going on here exactly?
> > > > > > > > 2) How can I enter other parameters so that the error does not
> > > > > occur
> > > > > > > and no reheat is nessesary.
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > > --
> > > > > > 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
> > > > > >
> > > > >
> > > > >
> > > >
> > > > --
> > > > 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
> > > >
> > >
> >
>