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Re: [EnergyPlus_Support] Re: Exceeding maximum iterations problem
Hello zhen
Energy Plus has been used in Design of the Biggest Building of all : THE NEW WORLD TRADE CENTER : FREEDOM Tower foundation stone of which was laid on July 4th , i would invite you to see its pictures are at http://www.som.com/press_release/
Some others are Sanfransico Federal building etc , there are many others. Kindly read the earlier email in the group you will get some information about architects/engineers from all over the world using it in design.
Currently i am working on a The Smart Energy Project where over 20 New to be Constructed Building across the State of Illinois, are being analysed for Energy efficiency. The Smart Energy Design Assistance Center is Using Energy Plus to Design and Retrofit New and Old business/ industries for energy efficiency.
Regarding iteration errors/ other queries kindly wait i am sure some more experienced team member would respond soon.
Thanks
Rahul Chillar
Graduate Research Assistant
Building Systems Lab
University of Illinois UC
zhen tian <tianzhen9@xxxxxxxxx> wrote:
I had this iteration problem tried this method before.
I found this problem was related to the zone number and zone equipment. The more zones, and the more equipement in the same zone, the more possibilty of this iteration problem.
I found that if you set the convege tolerance to 0.00005, and this still appear, even you set minor values, this method will not work.
Try to change the ousiside temperature limit from 19 to 20 or 18, this warning may go away. The example file uses 19 degree C, but I do not think it is correct. It should be around 24 to 26. You can give me a response if it works.
>From my perepective view, it will be better for the uses if Energyplus can focus on solve and improve the prolems in the existing models rather than to incorporate new models right now.
By the way, I want to ask if somebody or some company has succeedly used Energyplus for simulating of real big building projects.
Regards, Zhen
bsiengineer <arch_engel@xxxxxxxxxxx> wrote:
Rahul,
Thank you for your help. I have made several simulation runs with
different convergence tolerances (both increased and decreased
values) on the cooling coil controller and reheat controllers but
these changes have had no effect on the number of iterations reported
in the error file. Does anybody have any other suggestions?
Thanks, David
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Rahul Chillar
<chillarrahul@y...> wrote:
> Hello
> This same problem had occured with a user earlier , ........... Max
> Iteration errors can be eliminated by increasing the convergence
tolerance
> on your controllers
>
> For example look at the controller information below and you will
easily figure out how to solve that. If it does not kindly let us
know so that we can look at your file which you uploaded.
>
> EARLIER CASE with problems:
>
> CONTROLLER:SIMPLE,
> Central Cooling Coil Contoller 1, !- Name
> TEMP, !- Control variable
> Reverse, !- Action
> FLOW, !- Actuator variable
> VAV Sys 1 Outlet Node, !- Control_Node
> Cooling Coil Water In, !- Actuator_Node
> 0.002, !- Controller Convergence Tolerance: delta
> temp from setpoint temp {deltaC}
> autosize, !- Max Actuated Flow {m3/s}
> 0.0000001; !- Min Actuated Flow {m3/s}
>
>
> CONTROLLER:SIMPLE,
> Central Heating Coil Contoller 1, !- Name
> TEMP, !- Control variable
> Normal, !- Action
> FLOW, !- Actuator variable
> VAV Sys 1 Outlet Node, !- Control_Node
> Main Heating Coil 1 Water Inlet Node, !- Actuator_Node
> 0.002, !- Controller Convergence Tolerance: delta
> temp from setpoint temp {deltaC}
> autosize, !- Max Actuated Flow {m3/s}
> 0.0000001; !- Min Actuated Flow {m3/s}
>
> These values created over 350 Max Iteration warnings. Then the
values were
> changed to:
> CONTROLLER:SIMPLE,
> Central Cooling Coil Contoller 1, !- Name
> TEMP, !- Control variable
> Reverse, !- Action
> FLOW, !- Actuator variable
> VAV Sys 1 Outlet Node, !- Control_Node
> Cooling Coil Water In, !- Actuator_Node
> 0.001, !- Controller Convergence Tolerance: delta
> temp from setpoint temp {deltaC}
> autosize, !- Max Actuated Flow {m3/s}
> 0.0000001; !- Min Actuated Flow {m3/s}
>
>
> CONTROLLER:SIMPLE,
> Central Heating Coil Contoller 1, !- Name
> TEMP, !- Control variable
> Normal, !- Action
> FLOW, !- Actuator variable
> VAV Sys 1 Outlet Node, !- Control_Node
> Main Heating Coil 1 Water Inlet Node, !- Actuator_Node
> 0.001, !- Controller Convergence Tolerance: delta
> temp from setpoint temp {deltaC}
> autosize, !- Max Actuated Flow {m3/s}
> 0.0000001; !- Min Actuated Flow {m3/s}
>
> The errors were reduced to over 50 Max iteration warnings.
>
> When Values Changed to
> CONTROLLER:SIMPLE,
> Central Cooling Coil Contoller 1, !- Name
> TEMP, !- Control variable
> Reverse, !- Action
> FLOW, !- Actuator variable
> VAV Sys 1 Outlet Node, !- Control_Node
> Cooling Coil Water In, !- Actuator_Node
> 0.0001, !- Controller Convergence Tolerance: delta
> temp from setpoint temp {deltaC}
> autosize, !- Max Actuated Flow {m3/s}
> 0.0; !- Min Actuated Flow {m3/s}
>
>
> CONTROLLER:SIMPLE,
> Central Heating Coil Contoller 1, !- Name
> TEMP, !- Control variable
> Normal, !- Action
> FLOW, !- Actuator variable
> VAV Sys 1 Outlet Node, !- Control_Node
> Main Heating Coil 1 Water Inlet Node, !- Actuator_Node
> 0.0001, !- Controller Convergence Tolerance: delta
> temp from setpoint temp {deltaC}
> autosize, !- Max Actuated Flow {m3/s}
> 0.0; !- Min Actuated Flow {m3/s}
>
>
> ALL MAX ITERATION ERROR ELIMINATED.
> Try the same procedure in your file , i am sure they will go away.
These occur because outer loop has higher tolerance set than inner
loop . Hence it is unable to converge.
> If they go away with above change you need not worry about the
results even if you loosen up the tolerance.
>
> Thanks
> Rahul Chillar
> Graduate Research Assistant
> Building Systems Laboratory
> Univerisity of Illinois UC
>
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>
> bsiengineer <arch_engel@h...> wrote:
> My simulation is having a problem of exceeding the maximum
iterations
> on the HVAC system. I am simulating two interior rooms served by a
> single-duct VAV reheat system. This model has previously been run
> successfully with a single-duct constant volume system. The system
> is electric preheat and reheat, and purchased chilled water
cooling,
> so it's fairly simple.
>
> I will upload my file, Iterations.idf, to the
> folder "Problem_Submittals". Can anyone help me figure out what is
> going wrong?
>
> Thanks!
>
>
>
>
> The primary EnergyPlus web site is found at:
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>
> Thanks
> Rahul Chillar
> Grad Student
> Building Systems lab
> Univ Of Illinois Urbana Champaign
>
>
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Thanks
Rahul Chillar
Grad Student
Building Systems lab
Univ Of Illinois Urbana Champaign
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