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Re: [EnergyPlus_Support] FindRootSimpleController Sever errors





Hi Karen


Perhaps your AHU starts before your CHW plant? I've seen this error pop up in that case. I suggest getting outputs at the timestep level and then checking if this occurs at the timestep the error is reported.


Regards,

Benson




From: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx> on behalf of Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Tuesday, 12 July 2016 3:35 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] FindRootSimpleController Sever errors
 
 

Karen,
I haven't had one of those for a while, but suspect there's a setpoint that's off.

Using the clues provided in the error message, why do you suppose the water temp is 

   **   ~~~   ** Controller sensed temperature = 16.65 [C], considerably higher than the 12.4C setpoint? Is your chiller and pump working?



On Mon, Jul 11, 2016 at 12:34 PM, rajeevkamal@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
 

One of idf model I am working is showing me the Controller error as bellow for all the VAV Cooling coil controller


** Severe  ** FindRootSimpleController: Controller error for controller = "VAV_1_COOLC_CONTROLLER"

   **   ~~~   **  Environment=ANNUAL, at Simulation time=01/27 18:40 - 18:50

   **   ~~~   **   Controller function is inconsistent with user specified controller action = "" action

   **   ~~~   **   Actuator will be set to maximum action

   **   ~~~   ** Controller control type=Temperature

   **   ~~~   ** Controller temperature setpoint = 12.40 [C]

   **   ~~~   ** Controller sensed temperature = 16.65 [C]

   **   ~~~   ** Controller actuator mass flow rate set to 10.87 [kg/s]

   **   ~~~   ** Controller actuator temperature = 16.67 [C]

   **   ~~~   **   Note: Chilled water coils should be reverse action and the entering chilled

   **   ~~~   **         water temperature (controller actuator temperature) should be below the setpoint temperature

   **   ~~~   **   Note: Hot water coils should be normal action and the entering hot

   **   ~~~   **         water temperature (controller actuator temperature) should be above the setpoint temperature


I have set the ChilledWater coils to reverse action and my Controller is using setpointmanager as


SetpointManager:MixedAir,

    VAV_1_CoolC SAT Manager, !- Name

    Temperature,             !- Control Variable

    VAV_1 Supply Equipment Outlet Node,  !- Reference Setpoint Node Name

    VAV_1_HeatC-VAV_1_FanNode,  !- Fan Inlet Node Name

    VAV_1 Supply Equipment Outlet Node,  !- Fan Outlet Node Name

    VAV_1_CoolC-VAV_1_HeatCNode;  !- Setpoint Node or NodeList Name


*************  ** Severe  ** FindRootSimpleController: Previous controller action error continues for controller = VAV_1_COOLC_CONTROLLER

   *************  **   ~~~   **   This error occurred 11 total times;

   *************  **   ~~~   **   during Warmup 0 times;

   *************  **   ~~~   **   during Sizing 0 times.


I get 48 of these warnings with year of simulation. Can this be ignored safely considering only 12 times in a year for each controller.





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James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l  LinkedIn | May 2016 ASHRAE Journal article on energy modeling

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Posted by: Benson Coelho <ben_coelho@xxxxxxxxxxx>


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