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[EnergyPlus_Support] Re: ** Warning ** SimHVAC: Maximum iterations (40) exceeded
Dear Brent, Richard and others,
I've taken a look at these Report Variables, and I'm not quite sure what some of the information means.
An example is:
** ~~~ ** 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
This appears that everything is OK for the HVAC tolerance issues, since all the values are zero. I don't know what these flags represent, though. Do you?
For the PlantFlow Tolerance flags, I appear to have problems:
** ~~~ ** Plant Tolerance Flags=[01000101] Enthalpy[0],MassFlow[1],HumRat[0],Pressure[0],FlowQual[0],Energy[1],Temp[0],PlantFlowMassFlow[1]..0=ok,1=fail
** ~~~ ** Plant Tolerance Values, Most Recent listed first
** ~~~ ** Plant EnthalpyTol=0.000, MassFlowTol=3.758, HumRatTol=0.0000, PressureTol=0
** ~~~ ** FlowQualTol=3.76, EnergyTol=1018145.415, TempTol=0.00
.........
** ~~~ ** PlantFlowFlowTol=3.758
I've searched my Report Variable values, which include total air and water flows, but these highlighted values do not show up anywhere. So once again, I'm not sure what they are.
It would help to know what flow is referred to: Airflow or water flow? Same question for mass, although I suspect that solving a flow problem will also resolve the mass problem.
I suspect, too, that "PlantFlow" always refers to a Plant Loop. In my case, that's a hot water heating loop.
In summary:
1) If I fail an HVAC tolerance flag, where do I look for a cause? or what should I report more extensively to see what's going on?
2) If I fail a Plant Tolerance flag, where do I look for a cause?
3) Are the flows referred to in the tolerance flags airflow or waterflow?
Thanks!
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Griffith, Brent" <brent_griffith@...> wrote:
>
> System iterations are also a report variable. I recommend exploring
> when the issues occur by looking at the number of iterations reported at
> the timestep or detailed frequency. See the RDD file of course, but the
> variables are 'HVACManage Iterations' and 'SimAir Iterations'
>
>
>
> ________________________________
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of JV Dirkes II
> Sent: Wednesday, July 23, 2008 6:27 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: ** Warning ** SimHVAC: Maximum
> iterations (40) exceeded
>
>
>
> Dear Brent,
>
> That's helpful!
> I think I'm in the "when things are changing quickly" situation, but
> there are a LOT of "recovery from setback" situations during a year;
> almost every morning in my case. When there are more than a dozen or
> so of these max iteration conditions, E+ just condenses the rest of
> them into a message saying that you had "XX" max iteration warnings.
> This, of course, means that you don't really know where they're all
> coming from. My hope is that the first few are representative; if
> not, I'll be forced to guess a lot.
>
> I was hoping to figure out a process that helped identify the source
> of most of the iteration errors. In my current model, there are
> relatively few unmet load hours, which I take as a good sign.
> Nonetheless, there are 2800 maximum iteration warnings and that seems
> like a lot...
>
> Any other hints?
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> , "Griffith, Brent"
> brent_griffith@ wrote:
> >
> > Good question, difficult to answer. Here are my 2 cents,
> >
> >
> >
> > It is something to be concerned about, but in many cases there does
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