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RE: [EnergyPlus_Support] Very High airflow / ton of cooling

The DX coil model will always issue the severe warning unless you to use
a CFM/ton that lies in the model's range.  If the OA requirements are
large, the DX system's capacity will have to rise to meet them.  

 

I believe what you need to check into is the Zone Sizing object's
outside air method-probably needs to be "Flow/Zone" with the local code
requirements in m3/s set in the Outside Air Per Zone field.  

 

________________________________

From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of JV Dirkes II
Sent: Monday, March 10, 2008 7:49 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Very High airflow / ton of cooling

 

Dear EPlus Support,

I am modeling a building for a LEED project and must prepare a model
using a packaged rooftop AC system for the "baseline". This building
is a professional (medical) office building which must also comply
with minimum airflow requirements set by the local health code. As a
result, my System has over 1000CFM / ton and I get an error when
running the model.

The error is:
** Severe ** Sizing: COIL:DX:COOLINGBYPASSFACTOREMPIRICAL
"CLGCOIL_AH1": Rated air volume flow rate per watt of rated total
cooling capacity is out of range. See Input-Output Reference Manual
for valid range.

My system is a FURNACE:HeatCool object using a
COIL:DX:CoolingBypassFactorEmpirical cooling coil. I have selected
"design day with limit" in the ZONE SIZING (to force the known minimum
airflow rate) and "design day" in the SYSTEM SIZING.

The COIL:DX:COOLINGBYPASSFACTOREMPIRICAL object started out with
"autosize" selected for both Cooling Capacity and Airflow. I later
tried manually inputting the Cooling Capacity without success.

I will very much appreciate suggestions about how to model this
admittedly unrealistic system!

 



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