[EnergyPlus_Support] Re: About the heating load

["civilnug" <civilnug@xxxxxxxxx>]

I was getting the exact same warning in a simulation I am working on 
at the momemt. I had values in SYSTEM SIZING for 
Central cooling design supply air temperature {C} and 
Central heating design supply air temperature {C}
different values in ZONE SIZING for 
Zone cooling design supply air temperature {C} and
Zone heating design supply air temperature {C}.

I have a single zone single duct VAV with no reheat but when 
I made the heating supply temperature the same for the system and 
the zone and likewise for the cooling supply temperatures it got rid 
of the warning.

John McCarthy.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "beyangj" <beyangj@h...> 
wrote:
> 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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