Mismatched Component Sizes OpenStudio Error

asked 2021-07-14 09:56:39 -0500

Scott Crowner gravatar image

updated 2021-07-18 14:15:33 -0500

I'm making an OpenStudio model of an existing building with multiple air handling units. The error file is indicating there is a discrepancy between the design size and user-specified size of many HVAC components including the fans, heating coils, and cooling coils. For example, here is the the error for a fan:

   ************* SizeFan: : Potential issue with equipment sizing for Fan:VariableVolume VAR SPD FAN 17
   **   ~~~   ** User-Specified Maximum Flow Rate [m3/s] = 0.66000
   **   ~~~   ** differs from Design Size Maximum Flow Rate [m3/s] = 1.81696
   **   ~~~   ** This may, or may not, indicate mismatched component sizes.
   **   ~~~   ** Verify that the value entered is intended and is consistent with other components.

The heating and cooling coils are hydronic and their error messages look the same as above, indicating there is a discrepancy in their water flow rates. Assuming the model proceeds with the design size instead of my specified size, this might explain why the fans' electric loads are unrealistically high and the coils' loads are unrealistically low in my model. How do I resolve this? Did I autosize something I shouldn't have?

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