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Warning design cooling coil US

asked 2016-05-12 22:40:53 -0500

rkbest's avatar

updated 2016-05-13 11:03:55 -0500

I am getting the following warnings, and I wanted to know the significance of these. I picked Cooling coil water and Chiller:Electric: EIR based on an example idf file.

Error files include:

** Warning ** In calculating the design coil UA for Coil:Cooling:Water COIL COOLING WATER 1
**   ~~~   ** no apparatus dew-point can be found for the initial entering and leaving conditions;
**   ~~~   ** the coil outlet design conditions will be changed to correct the problem.
**   ~~~   ** The initial design conditions are: Tair,in = 25.9241
**   ~~~   **                                    Wair,in = 1.816273E-002
**   ~~~   **                                    Twater,in = 7.5000
**   ~~~   **                                    Tair,out = 12.8000
**   ~~~   **                                    Wair,out = 8.281818E-003
**   ~~~   ** The revised design conditions are: Tair,out = 12.7997
**   ~~~   **                                    Wair,out = 8.281922E-003
** Warning ** Chiller:Electric:EIR = CHILLER ELECTRIC EIR 1:  Integrated Part Load Value (IPLV) calculated is not at the AHRI test condition.
**   ~~~   **  Check limits in Cooling Capacity Function of Temperature Curve, Curve Type = BIQUADRATIC, Curve Name = CURVE BIQUADRATIC 1
**   ~~~   **  Check limits in EIR Function of Temperature Curve, Curve Type = BIQUADRATIC, Curve Name = CURVE BIQUADRATIC 2
** Warning ** SetpointManager:Scheduled="SETPOINT MANAGER SCHEDULED 1"
**   ~~~   ** ...setpoint node conflicts with another setpoint manager.
**   ~~~   ** ...conflicting setpoint manager = SetpointManager:OutdoorAirReset:"AHU1 OUTLET SETPOINT"
**   ~~~   ** ...conflicting node name = AIR OUTLET NODE1
**   ~~~   ** ...control type variable = Temperature
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When you post error logs like this, please make sure you have at least four spaces before the first * so that it shows up as code like I did for you. You can use notepad++ or any text editor, select the text and use TAB (or SHIFT+TAB to unindent) to do it quickly. This helps readability a lot. Thanks!

Julien Marrec's avatar Julien Marrec  ( 2016-05-13 05:09:43 -0500 )edit

Will do it in future, thanks

rkbest's avatar rkbest  ( 2016-05-13 07:17:48 -0500 )edit

1 Answer

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answered 2016-05-13 07:42:58 -0500

updated 2017-12-08 11:26:51 -0500

This warning indicates a sizing issue with the entered coil air outlet condition, in this case Tair,out = 12.8 C and w air,out = 0.00828818. These inputs are specified in the Coil:Cooling:Water object. When sizing the water coil, the model looks to find coil surface temperature, or where the air saturation point is on the psychrometric chart. If you draw a line from the air inlet condition to the air outlet condition on a psyc chart, that line should cross the saturation curve (e.g., 100% RH curve). The intersection of the airside line with the saturation curve denotes the coil surface temperature. If the model cannot find that crossing point, the model will try to adjust the outlet air condition such that the line does intersect the saturation curve.

This warning can be disregarded since the model was able to size the coil. However, if you do not agree with the results you can modify the coil inputs yourself to model a different coil.

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Thanks, Any suggestion for the Chiller:Electric:EIR curve warnings here. In the EP documentation the Curves used are DOE-2 Centrifugal/5.50COP CAPFT, !- Cooling Capacity Function of Temperature Curve DOE-2 Centrifugal/5.50COP EIRFT, !- Electric Input to Cooling Output Ratio Function of Temperature Curve DOE-2 Centrifugal/5.50COP EIRFPLR,

If I use these values the curve three is not accepted due to missing coefficient 5 &6 and min - max of y. So I used curve1 for the 'Electric Input to Cooling Output Ratio Function of PLR curve and got the above warnings.

rkbest's avatar rkbest  ( 2016-05-16 11:49:21 -0500 )edit

The warnings relate to: "Integrated Part Load Value (IPLV) calculated is not at the AHRI test condition". The CAPFT and EIRFT min/max curve limits do not allow the IPLV to be calculated at the specific operating points used to calculate IPLV.

rraustad's avatar rraustad  ( 2019-05-20 12:50:39 -0500 )edit

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Asked: 2016-05-12 22:40:53 -0500

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Last updated: Dec 08 '17