Problem with No Connection found for Return Air from Zone

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.

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.

29.7k

Julien Marrec

answered 2021-03-23 03:17:48 -0500, updated 2021-03-23 03:19:23 -0500

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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 (2021-03-23 03:38:58 -0500) 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 (2021-03-23 04:13:15 -0500) edit

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Problem with No Connection found for Return Air from Zone

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Problem with No Connection found for Return Air from Zone