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[EnergyPlus_Support] Re: Airloop maximum iterations.
I checked each one of my airloop nodes and they all make sense. I think it is having trouble starting up in the morning and trying to reach it's set point immediately. These warnings exist for ~20 mins when going from a 29 C temp in the coil (when it's in night time mode) to a 10 C temp (dehumidification) on startup. After the 20 mins though, the airloops stop having errors and the nodes are all making sense.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> I am guessing this is a VAV system. Check the temperature at the inlet
> of the cooling coil and see if it is below 12.8C.
>
> Output:Variable, CoilInletNodeName here ,System Node Temp,detailed;
>
> There also may be nothing wrong with the results since the tolerances
> you show do imply convergence. A good check of the results would be
> necessary to convince yourself of that (i.e., make sure the HVAC system
> are operating correctly).
>
> On 9/30/2010 9:05 AM, grandocu wrote:
> >
> > Yes I am and yes they are set to always available. It only happens on
> > the hour when I go from cycling on any zone at 18 C to running the
> > airloop system at a setpoint at 12.8 C. Coincidentally, there is no OA
> > allowed during night as well so when it starts, the system has a load
> > to deal with and now OA ventilation. Will this lead to a problem?
> > Should I try to modify the OA and warmup schedule to get rid of it or
> > might it be another reason.
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > <RRaustad@> wrote:
> > >
> > > The air loop can fail convergence for reasons other than tolerance.
> > > Are you getting many of these errors?
> > > Are you using chilled water coils? If so try setting the availability
> > > schedules for the water coil to always on and see if the message
> > disappears.
> > >
> > > On 9/30/2010 8:50 AM, grandocu wrote:
> > > >
> > > > Hello everyone,
> > > >
> > > > I have a warning that keeps popping up saying "Maximum iterations
> > (20)
> > > > exceeded" and the message below says the airloop failed, but all
> > > > tolerance values below are 0. Does anyone know why this message is
> > > > showing up if all the tolerance values are 0?
> > > >
> > > > ** Warning ** SimHVAC: Maximum iterations (20) exceeded for all HVAC
> > > > loops, at ANNSIM, 01/02 05:10 - 05:11
> > > > ** ~~~ ** SimFlags=[TFFFFFFF]
> > > >
> > AirLoops[T],ZoneEq[F],NonZoneEq[F],PlantLoops[F],CondLoops[F],ElecCircuits[F],PlantDemandLoops[F],CondDemandLoops[F]..F=ok,T=fail
> > > > ** ~~~ ** HVAC Tolerance Flags=[0000000]
> > > >
> > Enthalpy[0],MassFlow[0],HumRat[0],Pressure[0],FlowQual[0],Energy[0],Temp[0]..0=ok,1=fail
> > > > ** ~~~ ** HVAC Tolerance Values, Most Recent listed first
> > > > ** ~~~ ** HVAC EnthalpyTol=0.000, MassFlowTol=0.000,
> > HumRatTol=0.0000,
> > > > PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** HVAC side outlet node=[724 - AHU-B-6 RETURN AIR OUTLET]
> > > > ** ~~~ ** HVAC EnthalpyTol=0.000, MassFlowTol=0.000,
> > HumRatTol=0.0000,
> > > > PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** HVAC side outlet node=[723 - AHU-B-3 RETURN AIR OUTLET]
> > > > ** ~~~ ** HVAC EnthalpyTol=0.000, MassFlowTol=0.000,
> > HumRatTol=0.0000,
> > > > PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** HVAC side outlet node=[720 - AHU-B-5 RETURN AIR OUTLET]
> > > > ** ~~~ ** HVAC EnthalpyTol=0.000, MassFlowTol=0.000,
> > HumRatTol=0.0000,
> > > > PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** HVAC side outlet node=[719 - AHU-B-4 RETURN AIR OUTLET]
> > > > ** ~~~ ** HVAC EnthalpyTol=0.000, MassFlowTol=0.000,
> > HumRatTol=0.0000,
> > > > PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** HVAC side outlet node=[722 - CB AHU-B-2 RETURN AIR OUTLET]
> > > > ** ~~~ ** Plant Tolerance Flags=[00000000]
> > > >
> > Enthalpy[0],MassFlow[0],HumRat[0],Pressure[0],FlowQual[0],Energy[0],Temp[0],PlantFlowMassFlow[0]..0=ok,1=fail
> > > > ** ~~~ ** Plant Tolerance Values, Most Recent listed first
> > > > ** ~~~ ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
> > > > HumRatTol=0.0000, PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** Plant side outlet node=[390 - CB CONDENSER DEMAND OUTLET
> > NODE]
> > > > ** ~~~ ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
> > > > HumRatTol=0.0000, PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** Plant side outlet node=[347 - CHW_LOOP CNDW DEMAND OUTLET]
> > > > ** ~~~ ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
> > > > HumRatTol=0.0000, PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** Plant side outlet node=[383 - CB CONDENSER DEMAND INLET
> > NODE]
> > > > ** ~~~ ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
> > > > HumRatTol=0.0000, PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** Plant side outlet node=[342 - CHW_LOOP CNDW DEMAND INLET]
> > > > ** ~~~ ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
> > > > HumRatTol=0.0000, PressureTol=0
> > > > ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
> > > > ** ~~~ ** Plant side outlet node=[314 - HW_LOOP HW DEMAND OUTLET]
> > > > ** ~~~ ** Plant Flow Tolerance Values, Most Recent listed first
> > > > ** ~~~ ** PlantFlowFlowTol=0.000
> > > > ** ~~~ ** PlantFlowFlowTol=0.000
> > > > ** ~~~ ** PlantFlowFlowTol=0.000
> > > > ** ~~~ ** PlantFlowFlowTol=0.000
> > > > ** ~~~ ** PlantFlowFlowTol=0.000
> > > >
> > > >
> > >
> > > --
> > > 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
>
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