[EnergyPlus_Support] Re: Combination of the OA unit system and Fancoil unit system

["hbn_pch" <hbn_pch@xxxxxxxxxxxx>]

Hi,
   I'm sorry that i had another doubt.If all element are autosized,it 
seems that the oa unit always trid to meet the load because of its 
high priority for heating and cooling.And then all of the fancoil 
unit will not work at all.Is it right?But the real anticipant result 
is : oa unit tried to meet load first,and if it could't produced 
adequate energy,then fancoil will try to meet excess load.How to 
realize above controlld operation??

  Thanks very much! appreciated your kind help.

  pch

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "hbn_pch" <hbn_pch@y...> 
wrote:
>
> Dear sir,
>    I created a 3-zone model.Each zone has own fancoil unit to serve 
> and there is a indepent outside air unit to serve the three 
> zones.Fancoil units specifies no outside air(maximum outside air 
rate 
> set to 0),and their cooling source is a chiller,heating source is 
> purchased heating.
> The OA unit used another purchased cooling and purchased heating as 
> its cooling&heating source. The OA unit had high priority.
> 
>   After simulation,there are some warnings and severes as follows:
> 
>    ** Warning ** The design coil load is zero for 
COIL:Water:Cooling 
> RESISTIVE ZONE_FANCOILCOOLINGCOIL
>    **   ~~~   ** The autosize value for max water flow rate is zero
>    ** Warning ** The design coil load is zero for 
COIL:Water:Cooling 
> EAST ZONE_FANCOILCOOLINGCOIL
>    **   ~~~   ** The autosize value for max water flow rate is zero
>    ** Warning ** The design coil load is zero for 
COIL:Water:Cooling 
> NORTH ZONE_FANCOILCOOLINGCOIL
>    **   ~~~   ** The autosize value for max water flow rate is zero
>    ** Warning ** Check input. Pump nominal power or motor 
efficiency 
> is set to 0, for pump=CW PUMP
>    ** Warning ** Check input. Pump nominal volumetric flow rate is 
> set or calculated = 0, for pump=CW PUMP
>    ** Warning ** Check input. Pump nominal power or motor 
efficiency 
> is set to 0, for pump=OA HW PUMP
>    ** Warning ** Check input. Pump nominal volumetric flow rate is 
> set or calculated = 0, for pump=OA HW PUMP
>    ** Warning ** Check input. Pump nominal power or motor 
efficiency 
> is set to 0, for pump=COND PUMP
>    ** Warning ** Check input. Pump nominal volumetric flow rate is 
> set or calculated = 0, for pump=COND PUMP
>    ** Severe  ** COOLING TOWER:SINGLE SPEED "CENTRAL COOLING 
TOWER". 
> Free convection air flow rate must be less than the design air flow 
> rate.
>    ** Severe  ** COOLING TOWER:SINGLE SPEED "CENTRAL COOLING 
TOWER". 
> Free convection UA must be less than the design tower UA.
> 
>   It seems that the oa unit has produced adequate energy and the 
> fancoil units did't need to work(Is it right???).But there is a 
> problem for the OA HW Pump,it did't work at all.The cooling tower 
> did't work yet.Why???? 
> 
>   In ordoer to urge the oa unit and fancoil unit working together,i 
> tried to reduce the zone sizing temp from 14 to 4.And two units 
work 
> together as anticipant.Only leaving warnings of the OA HW Pump.But 
> changing the zone sizing temp to 4 is illogical,then what can i 
do???
> 
>   All of values are autosized.Can i specify the load produced by oa 
> unit(eg.specify maximum air flow rate of the direct air unit),and 
> auotsize the fancoil unit to decide their on/off????
> 
>   I don't know whether the combination of the two unit system is 
> correct.I hope somebody can help me.Thanks very much.
>   I've upload the file(pch.idf) to file area.
> 
>   Thanks again.
>   pch
>






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