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Error in PNNL model - Full service restaurant

asked 2021-10-28 13:43:50 -0600

Adharsh gravatar image

updated 2021-10-28 15:45:08 -0600

I used the PNNL model for Full service Restaurant ( Iam using Energyplus 9.5 and the model is reporting error like this

** Severe  ** CheckAirLoopFlowBalance: AirLoopHVAC PSZ-AC_2:2 is unbalanced. Supply is > return plus outdoor air.
**   ~~~   **  Environment=RUNPERIOD 1, at Simulation time=08/24 03:40 - 03:50
**   ~~~   **   Flows [m3/s at standard density]: Supply=8.388132E-004  Return=0.000000  Outdoor Air=0.000000
**   ~~~   **   Imbalance=8.388132E-004

No changes done on the model other than updating to the latest version How to fix this issue?? Thanks in advance.

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@Adharsh which code version of 90.1 or IECC are you running? Probably doesn't matter but if you know the climate zone that would be great.

Jeremy gravatar image Jeremy  ( 2021-10-28 17:28:25 -0600 )edit

Hi Jeremy, Thanks for responding , I used 90.1. Its showing the error. Then I tried the IECC too. IECC initial run went well but its too showing error now. I am wondering weather this is an issue in the model or my energy plus???

Adharsh gravatar image Adharsh  ( 2021-10-29 00:53:34 -0600 )edit

@Adharsh - which 90.1 version of the prototypes are you using? What's the climate zone of the model you're using? The models are code version and climate zone specific. For example: are you using the 90.1-2013 models in climate zone 4C?

Jeremy gravatar image Jeremy  ( 2021-10-29 10:36:17 -0600 )edit

Hi Jeremy, ASHRAE901_RestaurantSitDown_STD2013_NewYork.idf from "" I used the above IDF. I used NewYork weather file. As I got the error, tried with other weather files too and the error is same.

Adharsh gravatar image Adharsh  ( 2021-11-01 00:28:04 -0600 )edit

1 Answer

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answered 2021-11-02 10:37:56 -0600

The error seems to be occurring because the Fan:ZoneExhaust objects used in the model are currently set to be coupled with the HVAC system (default value for the System Availability Manager Coupling Mode). As a result, they are running when the system is night cycling and creating this flow imbalance.

If you set the System Availability Manager Coupling Mode to Decoupled for both Fan:ZoneExhaust, not only the error will go away but you'll capture the intended behavior of these fans.

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Asked: 2021-10-28 13:43:50 -0600

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Last updated: Nov 02