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[EnergyPlus_Support] Re: Max Iterations exceeded?
If I were to specify the design days by using the SizingPeriod:DesignDay object, the results get worse. So I used the SizingPeriod:WeatherFileConditionType as a temporary replacement to try and see what was causing which problem.
My max iterations are the reason some of the cooling coils are sizing to zero even though schedules, setpoint managers and governing thermostat setpoints are correctly defined. What difference do you think running the program using a 24 time step will do?
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
>
>
> SizingPeriod:WeatherFileConditionType,
> WinterDesignDay, !- Name
> WinterExtreme, !- Period Selection
> WinterDesignDay, !- Day of Week for Start Day
> No, !- Use Weather File Daylight Saving Period
> Yes; !- Use Weather File Rain and Snow Indicators
>
> SizingPeriod:WeatherFileConditionType,
> SummerDesignDay, !- Name
> SummerExtreme, !- Period Selection
> SummerDesignDay, !- Day of Week for Start Day
> No, !- Use Weather File Daylight Saving Period
> Yes; !- Use Weather File Rain and Snow Indicators
> ======================== I have never defined SummerDesignDay and WinterDesignDay in this way. So I cannot comment on what is happening. I debug the system usually using a 24 hour timestep data. The traces does not show much detail, and the general trends are correct. The outdoor air temperature and the zone mean air temperature were not shown. The IDF is generated from OpenStudio, that is why is so large in size. I am not used to this format. You are using VAV as well. The sechedules for DesignDay were not specifically defined. Dr. Li
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: gch2j2006@...
> Date: Fri, 3 Feb 2012 08:24:39 -0800
> Subject: Re: [EnergyPlus_Support] Max Iterations exceeded?
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> Dr Li-True. That is the first the cooling is turned on but it concerns me because big zones that I have called out for, their coils are sizing to be zero. I've attached both the IDF and a csv file of the output variables I've been looking at.
> In the csv file, if you look at chart 6, it is graphing the
> heating setpoints (in red), cooling setpoints (in green) along with the
> zone air temperature (in blue) for the two summer and winter design
> days. Everything is within the setpoints there.
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> Chart 7 graphs the same but during a month (July) typical for cooling.
> The blue line is always out of range for the cooling setpoints that I've
> specified.
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> Chart 8 graphs a month typical for heating (January) and the same thing
> happens. The schedules are not exactly what I want (but close enough)
> and the units don't seem to be meeting the demand of the zone enough to
> heat and cool the areas. Any thoughts?
>
>
> From: YuanLu Li <yli006@...>
> To: EnergyPlus_Support <energyplus_support@xxxxxxxxxxxxxxx>
> Sent: Thursday, February 2, 2012 2:20 PM
> Subject: RE: [EnergyPlus_Support] Max Iterations exceeded?
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> The reporting time is June 01 at 08:00 am. If this is the first time the cooling is turned on, you can ignore the warning.
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> If you get lots of these, there may be some incorrect sizing or scheduling program.
>
> The zone mean temperature and system cooling and heating rate usually will give the clue.
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> The long report simply says that the cooling plant is not turned on at that time, which could be at the heating and cooling change over point, if you have mixed thermostat types in use.
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> I cannot tell the problem by looking the error message alone.
>
> Dr. Li
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> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: gch2j2006@...
> Date: Thu, 2 Feb 2012 18:10:54 +0000
> Subject: [EnergyPlus_Support] Max Iterations exceeded?
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> I've been getting messages like this a lot. Wondering if anyone could help me out (Dr Li? Anyone?)
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> ** Warning ** SimHVAC: Maximum iterations (20) exceeded for all HVAC loops, at SDD, 06/01 08:00 - 08:06
>
> ** ~~~ ** SimFlags=[TFFFF] AirLoops[T],ZoneEq[F],NonZoneEq[F],PlantLoops[F],ElecCircuits[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=[610 - 0 CLASSROOMS RETURN AIR OUTLET]
>
> ** ~~~ ** HVAC EnthalpyTol=0.000, MassFlowTol=1.478E-011, HumRatTol=1.7347E-018, PressureTol=3.E-011
>
> ** ~~~ ** FlowQualTol=0.00, EnergyTol=3.135E-007, TempTol=3.55E-015
>
> ** ~~~ ** HVAC side outlet node=[609 - 5 OTHERS 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=[608 - 5 LABS 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=[607 - 5 CLASSROOMS 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=[606 - 4 OTHERS 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=[337 - CHILLED WATER PLANT CNDW SUPPLY 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=[345 - CHILLED WATER PLANT 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=[327 - CHILLED WATER PLANT CHW SUPPLY 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=[301 - HOT WATER PLANT HW SUPPLY 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=[333 - CHILLED WATER PLANT CHW DEMAND OUTLET]
>
> ** ~~~ ** Plant Flow Tolerance Values, Most Recent listed first
>
>
>
> I've tried changing different setpoints and messing with my schedules but nothing seems to work. The result of this is mostly that none of my zones receive the proper cooling (all the cooling coils have a nominal capacity of 0) and I see no end uses in cooling after the simulation.
>
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