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Error while modeling radiant underfloor cooling system

asked 2018-12-12 08:37:35 -0500

kkotenidisGRtuc gravatar image

updated 2019-01-22 06:22:02 -0500

Hello guys! I'm a student in Technical University in Crete and I've been struggling a couple of weeks in a project, in which I would like to model a radiant floor cooling system using "Low Temperature Radiant Variable Flow" and I'm getting the following warnings every time:

Error file results:

 Program Version,EnergyPlus, Version 9.0.1-bb7ca4f0da, YMD=2019.01.18 18:50,
   ************* Beginning Zone Sizing Calculations
   ** Warning ** ProcessScheduleInput: Schedule:Constant="ALWAYS ON DISCRETE", Blank Schedule Type Limits Name input -- will not be validated.
   ** Warning ** ProcessScheduleInput: Schedule:Constant="ALWAYS OFF DISCRETE", Blank Schedule Type Limits Name input -- will not be validated.
   ** Warning ** ProcessScheduleInput: Schedule:Constant="ALWAYS ON CONTINUOUS", Blank Schedule Type Limits Name input -- will not be validated.
   ** Warning ** GetHTSurfaceData: Surfaces with interface to Ground found but no "Ground Temperatures" were input.
   **   ~~~   ** Found first in surface=SURFACE 16
   **   ~~~   ** Defaults, constant throughout the year of (18.0) will be used.
   ** Warning ** CheckUsedConstructions: There are 1 nominally unused constructions in input.
   **   ~~~   ** For explicit details on each unused construction, use Output:Diagnostics,DisplayExtraWarnings;
   ** Warning ** Calculated design heating load for zone=THERMAL ZONE 4 is zero.
   **   ~~~   ** Check Sizing:Zone and ZoneControl:Thermostat inputs.
   ** Warning ** Calculated design heating load for zone=THERMAL ZONE 8 is zero.
   **   ~~~   ** Check Sizing:Zone and ZoneControl:Thermostat inputs.
   ************* Beginning Plant Sizing Calculations
   ** Warning ** GetElectricEIRChillerInput: Chiller:Electric:EIR="CHILLER - AIR COOLED"
   **   ~~~   ** Adding OutdoorAir:Node=CHILLER - AIR COOLED INLET NODE FOR CONDENSER
   ** Warning ** GetElectricEIRChillerInput: Chiller:Electric:EIR="CHILLER - AIR COOLED"
   **   ~~~   ** Energy input ratio as a function of temperature curve output is not equal to 1.0 (+ or - 10%) at reference conditions.
   **   ~~~   ** Curve output at reference conditions = 0.850
   ** Warning ** Output:Meter:MeterFileOnly requested for "Electricity:Facility" (TimeStep), already on "Output:Meter". Will report to both eplusout.eso and eplusout.mtr
   ************* Testing Individual Branch Integrity
   ************* All Branches passed integrity testing
   ************* Testing Individual Supply Air Path Integrity
   ************* All Supply Air Paths passed integrity testing
   ************* Testing Individual Return Air Path Integrity
   ************* All Return Air Paths passed integrity testing
   ************* No node connection errors were found.
   ************* Beginning Simulation
   ** Warning ** ZoneHVAC:LowTemperatureRadiant:VariableFlow [LOW TEMP RADIANT VAR FLOW 1]
   **   ~~~   ** Surface [SURFACE 28] temperature below dew-point temperature--potential for condensation exists
   **   ~~~   ** Flow to the radiant system will be shut-off to avoid condensation
   **   ~~~   ** Predicted radiant system surface temperature = 33.33
   **   ~~~   ** Zone dew-point temperature + safety delta T= 33.79
   **   ~~~   **  Environment=SOUDA/KHANIA ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10
   **   ~~~   ** Note that a 1.0000 C safety was chosen in the input for the shut-off criteria
   **   ~~~   ** Note also that this affects all surfaces that are part of this radiant system
   ** Warning ** ZoneHVAC:LowTemperatureRadiant:VariableFlow [LOW TEMP RADIANT VAR FLOW 6]
   **   ~~~   ** Surface [SURFACE 49] temperature below dew-point temperature--potential for condensation exists
   **   ~~~   ** Flow to the radiant system will be shut-off to avoid condensation
   **   ~~~   ** Predicted radiant system surface temperature = 32.67
   **   ~~~   ** Zone dew-point temperature + safety delta T= 38.23
   **   ~~~   **  Environment=SOUDA/KHANIA ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10
   **   ~~~   ** Note that a 1.0000 C safety was ...
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answered 2019-01-07 15:02:34 -0500

Based on the error messages, it appears that the radiant system has not been connected to a working plant loop. If that's not the case, please post the idf file.

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Hello @MJWitte! I made a heating and cooling plant loop for the Zone Equipment that I used (Low Temperature Radiant Variable Flow). You can check it to my updated model if you want.

Thank you for your help! I appreciate

kkotenidisGRtuc gravatar imagekkotenidisGRtuc ( 2019-01-22 06:25:15 -0500 )edit

Because this is a radiant system, use output variables "Zone Radiant HVAC Heating Energy" and cooling.

MJWitte gravatar imageMJWitte ( 2019-01-28 16:56:40 -0500 )edit

@MJWitte thank you for your help! I suppose my model is correct. One last question. Do you know how can I have results for CO2 emissions?

Thank's in advance!

kkotenidisGRtuc gravatar imagekkotenidisGRtuc ( 2019-01-29 05:05:37 -0500 )edit

See EnvironmentalImpactFactors and FuelFactors.

MJWitte gravatar imageMJWitte ( 2019-02-04 15:23:46 -0500 )edit
0

answered 2019-02-07 17:21:10 -0500

Ranjani gravatar image

@MJWitte I used the AEDG Radiant measure for my energy model. I removed the HW loop and added CW Loop and CT since the chillers are water cooled. But got the following! image description error-

image description

Can you help me with this?

Thanks

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It's still complaining about missing nodes and schedules. Will need to see your idf file in order to help further. Either post a link here are send as an attachment to the helpdesk at energyplus-support@gard.com

MJWitte gravatar imageMJWitte ( 2019-02-07 17:48:32 -0500 )edit

@MJWitte Sure, I can send the file to the email address above. I don't have a heating system and the missing component was that the radiant system wasn't assigned to any HW Loop (Under thermal zones tab) . Can I choose the CHW loop for both heating and cooling?

Ranjani gravatar imageRanjani ( 2019-02-07 17:53:44 -0500 )edit

ZoneHVAC:LowTemperatureRadiant:VariableFlow should work fine as cooling-only. Make sure that all of the fields related to the Heating side are left blank. From the error message, it appears that one of the heating fields has "autosize" in it.

MJWitte gravatar imageMJWitte ( 2019-02-08 14:04:57 -0500 )edit

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Asked: 2018-12-12 08:37:35 -0500

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Last updated: Feb 07