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Re: [EnergyPlus_Support] Simutanuous heating and cooling



My apologies for the delayed response . . .

In this model, the heating and cooling coil controllers both use the supply fan 
outlet as the Control Node.  This "downstream" control can cause the situation 
you describe, especially in a VAV system, due to small inaccuracies in control. 
 An alternate approach is to use the SET POINT MANAGER:MIXED AIR to place a fan-
heat-adjusted setpoint on the mixed air node (which it currently is) and the 
heating coil outlet node and the cooling coil outlet node.  This would then 
require changing the controller objects to use the coil outlet node as the 
control node.  This should give better control and eliminate the battling of 
the heating and cooling coils.

Mike


On 11 Oct 2005, at 22:37, zhaicq98 wrote:

> I am simulating a VAV system. There is a heating and cooling coil in 
> the air handling unit. When I ran the simulation and look at the 
> heating and cooling coil load, I found something strange. During winter 
> design day, the heating coil heats the air a bit hotter than what is 
> needed, and then the cooling coil needs to bring the air temperature 
> back to the setpoint. The load on the cooling coil is small though. I 
> could not figure out what is going on. I have uploaded the input file 
> to the "problem submittal" area under "files", with the name 
> simutanuous heating and cooling.idf. 
> 
> Thanks for your attention. I am looking forward to your response. 
> 
> -Chaoqin
> 
> 
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> 
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> Attachments are not allowed -- please post any files to the appropriate folder
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> 
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> "search" button.
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