[EnergyPlus_Support] question about autosizing

["zhaicq98" <chaoqinz@xxxxxxxxxxxxxx>]

Hi,

I have a question about the autosizing of the DX cooling coi. I have 
a one-zone building conditioned by a unitary system with DX cooling 
coil COIL:COOLING:BYPASSFACTOREMPIRICAL. I input the SHR of the 
cooling coil as 0.75. I ask the program to do the autosizing of the 
component whereever possible. But I got a severe error message:

  ** Severe  ** For object = COIL:DX:COOLINGBYPASSFACTOREMPIRICAL, 
name = "ROOFTOPUNIT_Z_SINGLE COOLING COIL", the combination of rated 
air volume flow rate, total cooling capacity and sensible heat ratio 
yields coil exiting air conditions above the saturation curve. 
Possible fixes are to reduce the rated total cooling capacity, 
increase the rated air volume flow rate, or reduce the rated sensible 
heat ratio for this coil.

I tried to reduce the coil SHR to 0.74, and it works. 

I have a thermostat object for this zone but I do not have a 
humidistat object. My understading is that the program will autosize 
the cooling coil in order to meet the thermostat setpoint and leave 
the indoor humidity as whatever it is. But it seems that this is not 
the case. 

I am wondering if anyone can give me some explanation on this issue. 
Thanks a lot.

-Chaoqin 





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