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Re: [EnergyPlus_Support] Re: Combination of the OA unit system and Fancoil unit system
Whenever there is a sizing question, the first place to look is in the eio
output file at the sizing reports. One this to note (which is not discussed in
the Input Output Reference) is that the sizing algorithms do no know how to
split loads between multiple systems. Each system serving a zone will be sized
to meet the full load of the zone. For this system type to work, you will
probably need to specify the supply air flow rate for one system or the other.
Some issues I've noticed so far:
1. The coil component sizing report lists "COIL:Water:Cooling, RESISTIVE
ZONE_FANCOILCOOLINGCOIL, Design Air Inlet Temperature [C], 13.000" and
"Design Air Outlet Temperature [C], 14.000". This is why the coil water flow
is sizing to zero. The 13C inlet temperature is coming from the SYSTEM SIZING
object - this appears to be a program error. I will ask someone else to look
at this more closely. Changing the SYSTEM SIZING cooling supply air
temperature to 15C allows the run to continue past this point.
2. The CONTROLLER:OUTSIDE AIR, OA CONTROLLER, minimum outside air flow rate
[m3/s] is 0.0000. There is no outside air in the OA system. The ZONE SIZING
objects indicate an outside air flow per person, but there are no PEOPLE
objects, so this becomes zero.
Mike
On 17 Oct 2005, at 9:14, hbn_pch wrote:
> Dear,
> Cry!
> According to above two issues,i test more and more time.I tried to
> change the priority of the OA unit and FanCoil unit.But i found the
> fancoil did't work yet.It also appeared that the design coil load is
> zero for cooling coil and heating coil in the zone fancoil unit.
> Now i really don't know how to fix the problem.
>
> Waiting your kind help.thanks very very much.
> pch
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "hbn_pch" <hbn_pch@y...>
> wrote:
> >
> > 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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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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