[EnergyPlus_Support] Multispeed Fan & Unitary System

["shadoworion57000@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

Hi all,

I want to transpose a DOE-2 model to Energy+. What I want to model is a multi-speed fan as part of a unitary system. For that, I am using a Fan:OnOff and AirLoopHVAC:UnitarySystem. I read the input/output reference guide and assigned the same "fan power ratio function of speed ratio curve" to the Fan:OnOff object as in my DOE-2 model. I would like my minimum supply flow to be 60% of the maximum airflow rate. The I/O reference guide states for Fan:OnOff: 

"If modeling multi-speed fan operation, this object must be used as part of a compound object that allows multiple fan speeds (e.g., AirLoopHVAC:Unitary:Furnace:HeatCool, ZoneHVAC:PackagedTerminalAirConditioner, etc.).In this case, the ratio of the compound object air flow rate to the fan s maximum air flow rate is used to determine the power at alternate fan speeds."

My understanding is that I need to have the maximum air flow rate set to my Fan:On:Off object and the minimum to my AirLoopHVAC:UnitarySystem. I did that but when I run a simulation and create a hourly report I can see that my fan is always running at constant speed (expect when cycling due to the night cycle control).

What am I missing?

Thanks a lot for your help!

 

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Posted by: shadoworion57000@xxxxxxxxx

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