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OpenStudio - Cannot adjust airflow in one zone

asked 2015-09-21 14:23:29 -0500

updated 2017-05-03 19:23:34 -0500

Hi All, I am running an OpenStudio model (v1.8.0) where I seem to have one rogue zone on an airloop where it is the only zone (constant volume PSZ heat pump airloop, operating 24/7 with no setback).

I am attempting to increase the cooling minimum airflow in an effort to meet loads, but I cannot seem to adjust the cooling airflow at the zone level. I am trying to change it at the OS:Sizing:Zone level. Everything at the system level is set to autosize. The outside air is correct, but I can't get the zone airflow to go higher than the minimum outside air flow. The OA is around 200 cfm, and the design air flow should be around 600 cfm, but the minimum cooling airflow stubbornly stays no higher than the OA no matter what I try. I have lots of unmet cooling hours for just this zone.

Changing the cooling design air flow rate worked just fine for all other zones in the model, even an identical one on the floor below that is set up exactly the same, but for some reason nothing I do seems to impact this particular zone. I have played with the cooling design flow, cooling minimum air flow per zone area, cooling minimum air flow, nothing seems to impact it. If I hard-size the fan I can reduce (not eliminate) the unmet hours, but I still can't change the cooling minimum flow.

What am I missing that could be preventing this one single zone from increasing its minimum cooling airflow?

Thanks in advance for your advice!

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answered 2015-09-22 08:49:35 -0500

Hallelujah, I think I solved this. I changed the zone Cooling Design Air Flow Method from Design Day to Flow/Zone, and finally the airflow popped up to where I wanted it, and loads are met.

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I was struggling with the same problem in my model. You solution worked for me. Thanks for not leaving your question unanswered! :)

rsunnam's avatar rsunnam  ( 2015-10-13 10:37:39 -0500 )edit

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Asked: 2015-09-21 14:23:29 -0500

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Last updated: Sep 22 '15