[EnergyPlus_Support] Re: About the heating load

["beyangj" <beyangj@xxxxxxxxxxx>]

Dear Mike,
Thank you very much for your reply. The system in my model was a air-
cooled CAV system for commercial building. Yes, there were reheat 
coils in this system, and the zone setpoints were maintained by 
specifying the dayschedule. In order to compare the energy 
consumption of different systems, the IDF file for this CAV system 
was modified from the IDF file for VAV system, and there were no 
such warnings as mentioned before when running the IDF file for the 
VAV system. The inputs in the SYSTEM SIZING object for the CAV 
system are set as follow:

SYSTEM SIZING,
    CAV Sys 1,               !- name of an AIR PRIMARY LOOP object
    sensible,                !- type of load to size on
    autosize,                !- Design (minimum) outside air 
volumetric flow rate {m3/s}
    1,                       !- minimum system air flow ratio
    15.0,                    !- Preheat design set temperature {C}
    13,                      !- Central cooling design supply air 
temperature {C}
    16,                      !- Central heating design supply air 
temperature {C}
    noncoincident,           !- Sizing Option
    no,                      !- Cooling 100% Outside Air
    no,                      !- Heating 100% Outside Air
    .008,                    !- Central cooling design supply air 
humidity ratio {kg-H2O/kg-air}
    0.008,                   !- Central heating design supply air 
humidity ratio {kg-H2O/kg-air}
    design day,              !- cooling design air flow method
    0,                       !- cooling design air flow rate {m3/s}
    design day,              !- heating design air flow method
    0.0;                     !- heating design air flow rate {m3/s}

I still don¡¯t know why this happened, could you give me more 
advices?

Best,

Stewart 







--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" 
<mjwitte@g...> wrote:
> What type of system is this for?  Are there other heating coils 
such as reheat 
> coils?  Are the zone setpoints being maintained?  Check the inputs 
in the 
> SYSTEM SIZING object.  Coil sizing is determined by the specified 
supply air 
> temperatures, the system flow rate, and the mixed air temperature 
at the design 
> load condition.
> 
> Mike
> 
> 
> On 29 Apr 2005, at 8:55, beyangj wrote:
> 
> > Dear,
> > There was a warning in the ERR file as follow:
> > ** Warning ** The design coil load is zero for 
> > COIL:Water:SimpleHeating MAIN HEATING COIL 1
> >    **   ~~~   ** The autosize value for max water flow rate is 
zero
> >    **   ~~~   ** To change this, input a value for UA, change 
the 
> > heating design day, or lower
> >    **   ~~~   **   the system heating design supply air 
temperature
> > 
> > I don't know why this happened. I changed the heating design 
day, 
> > but it didn't work,and it gave the same warning message. And the 
> > Heating:Electricity [J](RunPeriod) in the Meter file wasn't 
zero, it 
> > was 3.90248E+12J, and the heating load is correct in this case? 
> > Thanks in advance!
> > 
> > Best,
> > 
> > Stewart
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 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@g...




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