AirLoop Component Sizing peak condition numbers

asked 2019-03-25 12:32:52 -0500

xchen gravatar image

updated 2019-03-25 13:46:05 -0500

Hi, I'm generating the airloop component sizing report and have the following questions for the Cooling Peak Conditions and Heating Peak Conditions.

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1). where in the model is the supply air temperature defined? The cooling (57.2F) and heating (104F) supply air temperatures don't match any settings in my model, at the coils, or OS:Sizing:System, or at the setpoint managers Is this some preset default values (14C for cooling and 40C for heating)?

2). how is the mixed air temperature calculated? I hardsized the OSA and supply air cfm in openstudio. And the hourly output shows that the correct cfm and it is 100% OSA system. I'm not sure where this 32F (0C) comes from.

3). how is the main fan air flow calculated? Is this autosized based on the loads and the OSA, SA and MA conditions listed in the table? I have 44,536cfm for OSA. I'm guessing the cooling peak supply cfm is autosized. How about the heating main fan air flow? Right now it shows that the SA (25,318cfm) is less than the OSA, and is only about 20% of that cooling main fan air flow rate(123,419cfm)

I went through the engineering reference manual, but couldn't find an answer, only some general description. Any inputs are appreciated.

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