Re: [EnergyPlus_Support] Warning msg for FCU -- ** Warning ** In calculating the design coil UA for Coil:Cooling:Water 1F:ZONE5 COOLING COIL

["Walter (Fred) Buhl" <wfbuhl@xxxxxxxxx>]

Unfortunately you can't specify the coil apparatus dew-point in EnergyPlus input. Your problem is
coming from the very moist entering conditions (see error message). If you don't want to change
your summer design day conditions or your outside air amount, there's not much you can do
with the template input. You will have to use the expanded input (look for file extension expidf) and change the 
inputs for Coil:Cooling:Water. Specifically try something like Design Outlet Air Temperature = 15.6, 
Design Outlet Air Humidity Ratio = .0106.

Fred Buhl

On Fri, Mar 4, 2011 at 10:12 AM, x z <xs.zhang.2010@xxxxxxxxx> wrote:

 

Hi Group,

 

I am a new user of EnergyPlus, and I am trying to use FCU template by learning from the example: HVACTemplate-5ZoneFanCoil.

 

I copied the HVACTemplate:Zone:FanCoil objects together with Boiler, Chiller template objects to my model. I set the cooling temperature 12.2C and I got warning msg during plant sizing period as below:

 

   ** Warning ** In calculating the design coil UA for Coil:Cooling:Water 1F:ZONE5 COOLING COIL
   **   ~~~   ** 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 = 28.0957
   **   ~~~   **                                    Wair,in = 1.690250E-002
   **   ~~~   **                                    Twater,in = 7.2200
   **   ~~~   **                                    Tair,out = 12.2000
   **   ~~~   **                                    Wair,out = 8.000000E-003
   **   ~~~   ** The revised design conditions are: Tair,out = 12.2455
   **   ~~~   **                                    Wair,out = 7.981631E-003

 

I realize this msg is related to my summer design day conditions, and set design day dry bulb temperature will decrese the number of warnings. And It seems that the msg is related to dew-point of my cooling coil, but I can't find place to specify my FCU design dew-point.

 

May I ask, does this relates to my SummerDesignDay conditions setup? How to eliminate this warning msg?

 

Thanks

 

XiaoSong ZHANG

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