Re: [EnergyPlus_Support] about node temperatures

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

If the pump power remains constant and the flow varies, low flows will get hot 
because the energy must go somewhere.  You either need to let the pump power 
vary (linear power would use coefficients of 0,1,0,0) or use a constant speed 
pump so the excess flow will go through the bypass.

Mike

On 14 Jan 2005, at 16:39, zhen tian wrote:

> 
> Hi, Mike:
> 
> Thanks for you reply. I have checked the pump input. Actually, I do use variable
> flow pumps with constant pump power.  But I cannot change rated pump power
> consumption to "autosize" as this will cause severe errors. I did not use any
> autosize function in my model.  I have upload my model named " ICT-NoRC-zt.zip "
> to the yahoo group. Could you check it for me? Thanks a lot. The weather file is
> Calgary, Alberta.
> 
> Regards,
> 
> Zhen 
> "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> My guess is that there is something wrong with the pump inputs.  Is this a
> variable flow system with constant pump power?  Look at the pump inlet and
> outlet temperatures, flow rate and pump electric power consumption.  This my
> reveal the problem.
> 
> Mike
> 
> 
> On 13 Jan 2005, at 16:09, zhen tian wrote:
> 
> > 
> > 
> > Hi everyone:
> > 
> > I am simulating a building with five zones serviced by a VAV system. I set up
> > the heating plant (purchased heating) temperature as 93 degree C.  The
> > simulation goes through well, but when I check the system node temperature, I
> > found that the "HW SUPPLY OUTLET NODE:System Node Temp[C](Hourly)" the
> > temperature sometimes are " 93, 93, 111.1, 1111.4, 93.2, 93.2, 3533.6...."
> > 
> > And even the "CW PUMP OUTLET NODE:System Node Temp[C](Hourly) " is like this:
> > " 1369.2, 2723.5, 11.7, 10.8, 1783.1..."
> > 
> > when I run the simulation in a typical summer day.
> > 
> > Could somebody tell me what is the problem?
> > 
> > Regards,
> > 
> > Zhen
> > 
> > 
> > 
> > 
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> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support      
> EnergyPlus-Support@xxxxxxxx
> 
> 
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