Re: [EnergyPlus_Support] two problems

["Michael J. Witte" <mjwitte@xxxxxxxx>]

1.  Another user had a similar problem with psychrometric errors.  In that 
case, it was caused by a detailed cooling coil where the controller min 
actuated flow rate was something very small, but > 0.  If this is the case with 
your simulation, set the min flow rate to zero, and the problem should be gone.

2.  To eliminate the hydronic slab system condensation shutoff conditions, you 
need to either make the zone air drier (as you suggest lowering the supply air 
temperature would help) or raise the chilled water supply temperature to the 
slabs.  I am not sure what the common practice is.

Mike

On 2 Nov 2004, at 23:36, pizzaalan wrote:

> 
> 
> Dear all
> 
> I have two idf files, the first one is VAV system with reheat coil. 
> it has warnings as follows no matter in design days or run period 
> runnings. I checked all the temperature and schedule inputs and 
> there are nothing wrong. Could anyone give any hints where the 
> problem is?
> 
> The second one is radiant panel system with 100% outside air. It has 
> warnings that surface temperature is lower than dew point 
> temperature and condensation occurs. Any suggestion to prevent this? 
> Should I decrease the temp setpoint where after cooling coil or 
> bring more outside air in? Thanks
> 
> ** Warning ** Temperature out of range [-100. to 200.] 
> (PsyPsatFnTemp)
>    **   ~~~   **  Occurrence info=MINNEAPOLIS MN USA TMY2-14922 
> WMO#=726580, 05/27 07:30 - 08:00
>    **   ~~~   **  Input Temperature=36911.04
>    ** Warning ** Calculated Humidity Ratio is invalid (PsyWFnTdbRhPb)
>    **   ~~~   **  Occurrence info=MINNEAPOLIS MN USA TMY2-14922 
> WMO#=726580, 05/27 07:30 - 08:00
>    **   ~~~   **  Dry-Bulb= 36911.04 Relative Humidity (fraction)= 
> 1.00 Pressure= 98200.00
>    **   ~~~   ** Calculated Humidity Ratio= -0.6639 ... Humidity 
> Ratio set to .00001
> 
> 
> 
> 
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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