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[EnergyPlus_Support] Re: Heating Coil and Cooling Coil are running simultaneously!?!?
Thank you very much for this reply,
I have been using:
1. HVACTemplate:System:VAV object to adjust setpoints, for heating setpoint was put to 24[C] and cooling setpoint was put to 18[C],
2. HVACtemplate:Zone:VAV objects use 11[C] Temp. difference adjusted for both zone heating and zone cooling.
3. Thermostat setpoints are 20[C] for heating and 22[C] for cooling.
Please advise.
Hisham
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "jeannieboef@..." <jeannieboef@...> wrote:
>
> You place a setpoint usually on the outlet node of the AHU. Depending
> on which setpointmanager you use to place the setpoint, the setpoint
> could dynamically change to best meet the load in the zone. Often both
> coils look at this same setpoint together with their relative entering
> air temperatures: based on this information each independant coil
> controller will actuate to best try and achieve the air setpoint that
> you placed on the AHU outlet (which may change dynamically the value
> to achieve).
>
> Therefore if the setpoint the AHU outlet (at a timestep) was 13 deg C
> (because the zone needed cooling, because some equipment has turned
> on), the heating coil entering air temperature was 10 deg C from cold
> outside air, and the cooling coil entering air is 16 deg C (for any
> number of reasons), then both coils will operate.
>
> Mit freundlichen Grü�en- Sent from my iPhone (excuse the brevity)
>
> i. A.
> Jean Marais
> b.i.g. bechtold
> Tel. +49 30 6706662-23
>
> On 18.12.2013, at 11:16, "hisham.rashrash" <hisham.rashrash@...>
> wrote:
>
> > Dear all,
> > Regarding this warning 'In HVACTemplate:System:VAV "VAV" the Heating
> > Coil Design Setpoint is greater than the Cooling Coil Design
> > Setpoint. This may cause the heating coil and cooling coil to
> > operate simultaneously. Check results carefully and adjust controls
> > if needed.'
> >
> > Please, can anyone explain how this HVACTemplate:System:VAV works? I
> > feel lost in questions, like:
> > Should heating and cooling coils run independently of each others
> > and only depend on thermal zones thermostats? Then, what if two
> > thermostats provided contradicting signals: a request for heating
> > and another for cooling?
> > And in case there are no contradicting signals, why there is a
> > possibility both coils are running together when heating coil
> > setpoint is higher than cooling coil setpoint? Is there some
> > 'invisible' thermostat E+ object between these two coils?
> >
> > Maybe my questions are too basic, but I really need help here.
> >
> > Thank you very much.
> >
> > Hisham
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "hisham.rashrash"
> > <hisham.rashrash@> wrote:
> > >
> > > Dear all,
> > >
> > > I got this warning:
> > >
> > > Program Version,EnergyPlus-Windows-64 8.1.0.008, YMD=2013.12.17
> > 17:18,IDD_Version 8.1.0.008
> > > ** Warning ** Output:PreprocessorMessage="ExpandObjects" has the
> > following Warning conditions:
> > > ** ~~~ ** Warning: In HVACTemplate:System:VAV "VAV" the Heating
> > Coil Design Setpoint
> > > ** ~~~ ** is greater than the Cooling Coil Design Setpoint. This
> > may cause the
> > > ** ~~~ ** heating coil and cooling coil to operate simultaneously.
> > Check results
> > > ** ~~~ ** carefully and adjust controls if needed.
> > >
> > > It seems like EnergyPlus puts a thermostat between coils? why
> > should they run at the same time?
> > >
> > > Please advise.
> > >
> >
> >
>
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