[EnergyPlus_Support] please help with modeling of roof top unit

["zhaicq98" <chaoqinz@xxxxxxxxxxxxxx>]

Hi,

I am trying to simulate a roof top unit, which includes a DX cooling 
coil, heating coil and variable speed fan. I am always getting a lots 
of warning messages, which 
said "COIL:DX:COOLINGBYPASSFACTOREMPIRICAL "MAIN COOLING COIL 1" - 
Air volume flow rate per watt of rated total cooling capacity is out 
of range." I checked the input output reference, and understood that 
there is a range for this factor. The range is from 0.00004699 to 
0.00006041 (m3/s)/W. The rated capacity of my DX coil is 20000 W, and 
the rated air flow rate is 1.1 m3/s, resulting in a factor inside the 
required range. 

I am modeling a VAV system, and the design flow rate of the system is 
1.1 m3/s. I set the minimum flow fraction of the system to be 0.3. 
Thus the actual flow rate of the system could go beyond the range 
required by the DX coil, when the system is operating. If I have to 
stick to the range, then the actual flow rate of my system can only 
vary between 0.00004699*1.1 = 0.94 and 0.00006041*1.1 = 1.21 m3/s. I 
think this is not a real VAV system performs. 

Can anyone tell me whether these warning messages matter or not? In 
addition, what is the proper way to deal with the system I am 
modeling?

Thanks a lot for your help.

-Chaoqin



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