[EnergyPlus_Support] Re: Plant temperatures are getting far too cold

["chilu32" <chilu@xxxxxxxxxxxxxxxx>]

Hi, I encountered a similar situation when modelling Vertical ground heat exchanger with heatpumps. The advice below from the helpdesk did the trick.

> I suspect the input called Cycle Time {hr} in the
> HeatPump:WaterToWater:EquationFit:Cooling object. Try setting it to the
> minimum of 0.0161. Basically this input sets a minimum floor on the
> capacity of the heat pump and it is too high. (We also want to remove that
> field and part of the model.)
>
> From the error file,
> PlantLoop Operation Dispatched Load = 461.4 {W}
> The requested load is far below the rated capacity 304000 W and that cycle
> time serves as a minimum duty cycle.
>
> Another issue to consider is to set up the cooling load based operation
> scheme differently so there is a lower range where no cooling is
> dispatched. As it is now its starts at 0.0 for the lower limit. You
> probably don't want to start to dispatch the cooling until the load has
> become significant relative to the size of the heat pump, say 10,000 W or
> something.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> If the simulation stops after you see Warmup {1} on the DOS screen, then 
> you can tell the program to report during warmup so you can see what's 
> happening.
> 
> Output:Diagnostics,ReportDuringWarmup;
> 
> On 8/22/2013 9:43 AM, Maria Sole wrote:
> >
> >
> > I have already tried to change the CHW Loop Setpoint Manager but the 
> > severe error is always the same, i mean the outlet temperature is 
> > every time different but is always too low.
> >
> > ------------------------------------------------------------------------
> > *From:* energyplus_mimis <welma.pereira@...>
> > *To:* EnergyPlus_Support@xxxxxxxxxxxxxxx
> > *Sent:* Thursday, August 22, 2013 2:57 PM
> > *Subject:* [EnergyPlus_Support] Re: Plant temperatures are getting far 
> > too cold
> >
> >
> > It seems like your set point temperature for the plant loop is very 
> > low, check the temperature schedule in the SetpointManager:Scheduled
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, "mariasole297" 
> > <mariasole297@> wrote:
> > >
> > > Hi,
> > > i'm tring to simulate the following heating and cooling system:
> > >
> > > Groung heat exchanger+ heat pump+ heating/cooling floor
> > >
> > > When I start the simulation E+ always returns this sever error.
> > >
> > > ** Severe ** Plant temperatures are getting far too cold, check 
> > controls and relative loads and capacities
> > > ** ~~~ ** Environment=SENZA TITOLO, at Simulation time=05/08 19:16 - 
> > 19:19
> > > ** ~~~ ** PlantLoop Name (SupplySide)= CHW LOOP
> > > ** ~~~ ** PlantLoop Setpoint Temperature=6.7 {C}
> > > ** ~~~ ** PlantLoop Inlet Node (SupplySide) does not have a Setpoint.
> > > ** ~~~ ** PlantLoop Inlet Node (DemandSide) does not have a Setpoint.
> > > ** ~~~ ** PlantLoop Outlet Node (SupplySide) has a Setpoint.
> > > ** ~~~ ** PlantLoop Outlet Node (DemandSide) does not have a Setpoint.
> > > ** ~~~ ** PlantLoop Outlet Node (SupplySide) "CHW LOOP SUPPLY SIDE 
> > OUTLET" has temperature=-105.3 {C}
> > > ** ~~~ ** PlantLoop Inlet Node (SupplySide) "CHW LOOP SUPPLY SIDE 
> > INLET" has temperature=7.1 {C}
> > > ** ~~~ ** PlantLoop Minimum Temperature=1.0 {C}
> > > ** ~~~ ** PlantLoop Maximum Temperature=98.0 {C}
> > > ** ~~~ ** PlantLoop Flow Request (SupplySide)=0.0 {kg/s}
> > > ** ~~~ ** PlantLoop Flow Request (DemandSide)=0.1 {kg/s}
> > > ** ~~~ ** PlantLoop Node (SupplySide) "CHW LOOP SUPPLY SIDE OUTLET" 
> > has mass flow rate =0.1 {kg/s}
> > > ** ~~~ ** PlantLoop PumpHeat (SupplySide)=3.4 {W}
> > > ** ~~~ ** PlantLoop PumpHeat (DemandSide)=0.0 {W}
> > > ** ~~~ ** PlantLoop Cooling Demand=218.9 {W}
> > > ** ~~~ ** PlantLoop Heating Demand=0.0 {W}
> > > ** ~~~ ** PlantLoop Demand not Dispatched=0.0 {W}
> > > ** ~~~ ** PlantLoop Unmet Demand=62323.8 {W}
> > > ** ~~~ ** PlantLoop Capacity=120000.0 {W}
> > > ** ~~~ ** PlantLoop Capacity (SupplySide)=120000.0 {W}
> > > ** ~~~ ** PlantLoop Capacity (DemandSide)=0.0 {W}
> > > ** ~~~ ** PlantLoop Operation Scheme=CHW LOOP OPERAZIONE
> > > ** ~~~ ** PlantLoop Operation Dispatched Load = 218.9 {W}
> > > ** ~~~ ** PlantLoop Operation Dispatched Load (SupplySide)= 218.9 {W}
> > > ** ~~~ ** PlantLoop Operation Dispatched Load (DemandSide)= 0.0 {W}
> > > ** ~~~ ** Branches on the Loop.
> > >
> > >
> > > I've tried to check the GSHPSimple-GLHE in the ExampleFile and get 
> > some changes but it doesn't work... Any ideas????
> > > Maria
> > >
> >
> >
> >
> >
> >
> > 
> 
> -- 
> Richard A. Raustad
> Senior Research Engineer
> Florida Solar Energy Center
> University of Central Florida
> 1679 Clearlake Road
> Cocoa, FL  32922-5703
> Phone:   (321) 638-1454
> Fax:     (321) 638-1439 or 1010
> Visit our web site at: http://www.fsec.ucf.edu
> 
> UCF - From Promise to Prominence: Celebrating 50 Years
>



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