RE: [EnergyPlus_Support] Re: AirTerminal:SingleDuct:ParallelPIU:Reheat not cycling

[YuanLu Li <yli006@xxxxxxxxxxx>]

I think the Parallel PIU fan is controlled by the flow rate of the main air path.  The fan comes on when the main air llow is lower than the set limit.  The fan itself may not have an available schedule field.
 
If you have the availability schedule field for the PIU or  the zone equiment, it should follow your night schedule and ignore the theremostat.
 
Otherwise, when you turn off the main air path, and when the zone temperature is low, the PIU fan will remain on.

 Dr. Li  

 

---

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: moana.reynau@xxxxxxxxx
Date: Wed, 15 Jun 2011 23:26:57 +0000
Subject: [EnergyPlus_Support] Re: AirTerminal:SingleDuct:ParallelPIU:Reheat not cycling

 

Thanks for the response!

Are you aware of way to go around this? My problem is that if I leave the PIUs available through out the night they will run continuously to maintain the setback temperature. I think because there is not throttle range (deadband) the control on the PIU matches the setpoint temperature and stays on. This seems to have a significant impact on the fan energy. I guess I can try to use an average between the two extremes (on/off). We are trying to model the ashrae baseline 8.

thanks

moana

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Chandan Sharma <csharma@...> wrote:
>
> Hi,
>
> If you asking to specify night cycle availability manager for parallel
> PIU, it is not possible. Currently, availability managers can not be
> specified separately for exhaust fans and PIUs. Instead, the
> availability status for AirLoopHVAC object is applied to these zone
> equipment. In future, this flexibility might be extended to exhaust fans
> and PIUs.
>
> Hope this helps.
>
> Chandan
>
> On 6/14/2011 4:23 PM, moana wrote:
> >
> > Hi All,
> >
> > Sorry if this is an obvious question but I haven't managed to get the
> > parallel PIU cycle at night. I got it work on the singleduct terminal
> > as in the example but unsuccessful with the parallel PIU.
> > Do they work with night cycle?
> >
> > Thanks
> >
> > Moana
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, "moana"
> > <moana.reynau@> wrote:
> > >
> > > Richard,
> > >
> > > Do you know if PIU parallel fan with electric reheat can utilize
> > cycling fan mode? I've been able to have the singleDuct:VAV:reheat
> > terminal cycle but not the parallel PIU...
> > >
> > > Thanks
> > >
> > > Moana
> > >
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > <RRaustad@> wrote:
> > > >
> > > > There is no deadband on Tstat setpoints in E+. If you want the fan to
> > > > cycle, set the fan operating mode schedule to 0. This only works for
> > > > systems that can utilize cycling fan mode. For example,
> > UnitarySystems,
> > > > Furnaces, and some ZoneHVAC equipment.
> > > >
> > > > AirLoopHVAC:Unitary:Furnace:HeatCool,
> > > > CyclingFanSchedule, !- Supply Air Fan Operating Mode Schedule Name
> &g

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