Re: [EnergyPlus_Support] Comparing Sys/Air temperaturs between Purchase Air & heat pump.

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The Purchased Air simulation is an ideal system and it is possible for it to 
precisely meet setpoint.  Other system types may be less precise due to the 
iterative nature of the simulation.  In your example, the largest error is 
0.03C, and most of the controls errors which is reasonable.  

Is the heat pump serving more than one zone?  Is the fan set for cycling or 
continuous fan?  Continuous fan will give more precise control than cycling fan.

Mike


On 4 Jan 2004, at 13:49, itamargoldberger wrote:

> Dear Support team,
> 
> We are using EnergyPlus for research purposes, and it is essential 
> that we can compare results of various runs. Unfortunately, although 
> the only change we have made between two runs is in the type of 
> acclimatization system, going from Purchase Air (PA) to a heat pump, 
> we cannot repeat the exact temperatures reached with the PA. 
> Instead, we receive with the HeatPump varying temperatures in the 
> vicinity of the target set-point. This does not stem form improper 
> sizing, as we use the auto-size feature, and the temperatures in 
> winter actually exceed the set-point a little. E.g, instead of being 
> exactly 20.5C during the heating period of a given day, we obtain the 
> values below: 
> 20.4691
> 20.5241
> 20.5200
> 20.5157
> 20.5138
> 20.5135
> 20.5133
> 20.5133
> 20.5123
> 20.5110
> Which are not constant, and usually exceed the set-point during most 
> of the hours, except in this case during the first hour. In other 
> cases the overheating starts even during the first hour.
> 
> The heat-pump we use is based on your file HeatPumpAuto.idf. 
> The two idf files are uploded to folder named: "PA and HeatPump 
> files" created today (4/1).
> We would like to stress the point that with Purchase Air we obtained 
> constant temperatures during the entire heating period, except the 
> first hour.
> 
> We will greatly appreciate a prompt reply how to handle the heatpump 
> in order to obtain constant temperatures.
> 
> Many thanks, and a happy new year,
> 
> Assoc. Prof. Rachel Becker
> Eng. Itamar Goldberger
> 
> 
> 
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> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx


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