Re: [EnergyPlus_Support] Zone heating loads and heating meter not equal

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

Are you allowing for pump heat in the hot/chilled water loops?  Try setting the 
pump head to zero to eliminate pump heat, then check again.  Also, the chiller 
efficiency is probably not constant (unless you are using the constant COP 
chiller).  First, check that the chiller evap heat transfer load matches the 
coil loads (plus pump heat).  Then look at the chiller COPs to  see if the 
electric consumption is reasonable.  Also, if the chilled/hot water loop 
temperatures are not maintaining setpoint at all times, there will be an 
imbalance until the loop returns to setpoint, but the energy should balance 
when summed over time.

Mike


On 25 May 2006 at 18:05, Sam Roose wrote:

> I have just uploaded a file called "DESIGN_DAY_WEATHERFILE" that works fine,
> except that the sum of the zone heating loads in the output file (total
> water heating coil energy for 25 zones) does not equal the "Heating:
> Electricity" meter, which is the same value as the boiler electricity once
> converted to kWh. The same occurs with cooling (sum of total water cooling
> coil rate vs cooling:electricity). With the file I have sent, the sum of the
> heating coils is 1.06 of the heating meter (should be 1.00) and the sum of
> the cooling coils is 0.47 (should be 0.33 due to a COP of 3 being used).
> 
> I have noticed I can bring the zone heating load sum more into line with the
> heating meter by changing the maximum and minimum supply temperatures in the
> autosizing inputs, but the values diverge again if I make a major design
> change.
> 
> The file was set up in version 1.2.3
> 
> Is the sum of the zone heating loads independent from the weather file? Is
> there some other reason this occurs?  Thanks in advance
> 
> Sam Roose
> 
> 
> 
> 
> 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.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the
> "search" button.
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 
> 


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





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