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Problem with No Connection found for Return Air from Zone

asked 2021-03-23 03:07:25 -0600

tri.ton99 gravatar image

updated 2021-03-23 03:08:51 -0600

Hi everyone,

I'm trying to add a fan in relief air from AirLoopHVAC:OutdoorAirSystem to control the ratio between Outdoor air and Return air in mixing box (by control the air flowrate between relief air and mixed air, because I could not place fan in outdoor air and return air). When I add Fan:VariableVolume in Relief Air, it warned me errors:

** Severe  ** GetAirPathData: AirLoopHVAC="WEST ZONE AIR SYSTEM", connection to zone.
**   ~~~   ** No Connection found for Return Air from Zone
**   ~~~   ** Expected node name ="WEST ZONE RETURN AIR NODE".

I modified from examples 2ZoneDataCenterHVAC_wEconomizer.idf .This is my current file 2ZoneDataCenterHVAC_wEconomizer_Temp_Fan.idf in EnergyPlus.

I am very happy with your helps. Thank you all.

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answered 2021-03-23 03:17:48 -0600

updated 2021-03-23 03:19:23 -0600

You placed the relief fan onto the main branch, when you should instead add it to the AirLoopHVAC:OutdoorAirSystem:EquipmentList (named West Data Center OA Equipment)

I located one example: Take a look at file 5ZoneAirCooledConvCoef.idf, circa line 2690: https://github.com/NREL/EnergyPlus/bl...

AirLoopHVAC:OutdoorAirSystem:EquipmentList,
  OA Sys 1 Equipment,      !- Name
  OutdoorAir:Mixer,        !- Component 1 Object Type
  OA Mixing Box 1,         !- Component 1 Name
  Fan:VariableVolume,      !- Component 2 Object Type
  Relief Fan 1;            !- Component 2 Name

If instead you wanted the fan placed before the AirLoopHVACOutdoorAirSystem (to control the total flow of return from zones), then your node connections just don't match.

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Thank for your solution. I tried it currently. Do I need to define Fan:VariableVolume for Zone Relief Fan (object in class: efficient, pressure, rate, ...) after added the relief fan to the AirLoopHVAC:OutdoorAirSystem:EquipmentList because it warned an error:

* Severe * Duplicate name found. name: "West Zone Relief Fan". Overwriting existing object.

If I did not define it warned me lack of some parameters (like minimum and maximum).

Thank for your support.

tri.ton99 gravatar image tri.ton99  ( 2021-03-23 03:38:58 -0600 )edit

This is my model after fixing.

Update: I deleted Fan:VariableVolum in AirLoopHVAC:OutdoorAirSystem:EquipmentList and it did not warn anything but I think it make no sense.

Please check it for me, I do not know that is an E+ bug or not. Thank you very much.

tri.ton99 gravatar image tri.ton99  ( 2021-03-23 04:13:15 -0600 )edit

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Asked: 2021-03-23 03:07:25 -0600

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Last updated: Mar 24