Air System Outdoor Air Limiting Factor can be wrong for simple OA controls due to tiny differences

[mjwitte]

Issue overview

Air System Outdoor Air Limiting Factor uses several < or > tests to determine if the OA flow rate has been constrained by a particular limiting factor (e.g. economizer, OA schedule, etc.). For simple OA controllers with no economizer, no min OA schedule, and no other constraints, this should always be zero. But occasional 1s show up due to tiny differences in comparing two values which should be equal, but due to different calculation paths for the two values, they differ out in the 10th decimal or so. Probably need to add a tolerance to one or more of these comparisons, and review the entire logic for this output.

Also, this output is reset to zero every time step inside CalcOAController which I'm pretty sure is not called if an airloop is off. Need a test file to prove this.

Details

Some additional details for this issue (if relevant):

• Version of EnergyPlus 9.6.0-b8f984adb5
• Discovered while investigating unexpected diffs in AirflowNetwork Crack Refactor #8759

Checklist

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• Defect file added (list location of defect file here)
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